000
FXUS63 KILX 291737
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1237 PM CDT FRI AUG 29 2008

.DISCUSSION...
ISSUED 1028 AM CDT FRI AUG 29 2008

MORNING SURFACE ANALYSIS SHOWS COLD FRONT SINKING SOUTHWARD INTO
THE OHIO VALLEY...WHILE DRIER AIRMASS SLOWLY FILTERS INTO CENTRAL
ILLINOIS FROM THE NORTH. SURFACE DEWPOINTS ARE STILL HOLDING IN THE
UPPER 60S AND LOWER 70S ACROSS THE KILX CWA...WHILE MUCH DRIER 50S
DEWPOINTS REMAIN FURTHER TO THE N/NW ACROSS IOWA AND WISCONSIN.
WITH ONLY WEAK NORTHERLY FLOW EXPECTED TODAY...HAVE UPDATED HOURLY
DEWPOINT GRIDS TO FEATURE A MUCH SLOWER INTRODUCTION OF DRIER AIR
INTO THE AREA TODAY. BASED ON CURRENT TRENDS...IT APPEARS THE
HUMID CONDITIONS WILL STICK AROUND INTO THE AFTERNOON...BEFORE
MUCH MORE COMFORTABLE AIR SETTLES IN THIS EVENING AND OVERNIGHT.
HAVE ALSO TRIMMED THE LOW CHANCE POPS ACROSS THE E/SE CWA...WITH
ONLY A 20 POP ALONG AND SOUTH OF I-70 IN CLOSER PROXIMITY TO THE
DEPARTING FRONT. HIGH TEMP FORECAST LOOKS PRETTY MUCH ON
TARGET...WITH AFTERNOON READINGS MAINLY IN THE LOWER TO MIDDLE
80S. HAVE SENT OUT AN UPDATED ZONE PACKAGE TO REFLECT THESE
CHANGES.



&&

.AVIATION...
ISSUED 1237 PM CDT FRI AUG 29 2008

LIGHT NORTHERLY FLOW IS NOTED ACROSS THE TAF SITES EARLY THIS
AFTERNOON IN THE WAKE OF A WEAK COLD FRONT NOW IN THE OHIO VALLEY.
DRIER AIRMASS IS SLOWLY FILTERING SOUTHWARD INTO THE AREA...WITH
SATELLITE SHOWING CLEAR SKIES ACROSS THE NORTHERN TERMINALS.
MEANWHILE...ENOUGH RESIDUAL LOW-LEVEL MOISTURE REMAINS ALONG AND
SOUTH OF I-72 TO PRODUCE SCT-BKN CLOUD COVER AT THE REMAINING
SITES. GENERAL TREND WILL BE FOR A REDUCTION IN CLOUD COVER AS THE
AFTERNOON PROGRESSES...SO WILL ONLY CARRY SCT040 AT KSPI...KDEC...AND
KCMI. SKIES CLEAR OUT ACROSS THE BOARD AFTER 00Z AND WINDS BECOME
LIGHT AND VARIABLE. WITH DRIER AIRMASS IN PLACE OVERNIGHT...DO NOT
THINK FOG WILL BE AN ISSUE. AFTER THAT...CLEAR SKIES AND LIGHT
E/NE FLOW WILL BE NOTED SATURDAY MORNING.


BARNES
&&

.PREV DISCUSSION...
ISSUED 258 AM CDT FRI AUG 29 2008
MASS OF THUNDERSTORMS SPLIT IN THE EVENING HOURS...WITH MOST OF
THE RAIN AND SEVERE WEATHER MOVING SW AND NORTH OF THE FA. ACTUAL
FRONTAL BOUNDARY HANGING BACK A BIT AS REMNANTS OF PRECIP MOVE OUT
OF THE CWA THIS MORNING. FRONT LOCATED ALONG AND JUST SE OF THE
ILLINOIS RIVER VALLEY AT FORECAST TIME. SOME PATCHY FOG DEVELOPING
TO THE WEST...AS WELL AS BEHIND THE SFC BOUNDARY WITH ALL OF THE
LLVL MOISTURE IN PLACE AFTER THE RAINFALL. NOT A LOT OF CHANGE AT
ALL TO THE FORECAST. FIRST CHALLENGE WILL BE THIS AFTERNOON IN THE
FAR SERN PART OF THE STATE AND ALONG THE OHIO RIVER VALLEY. ONLY
OTHER CHALLENGE AT THIS POINT IS TEMPERATURES AS A RIDGE BUILDS
OVER THE ERN HALF OF THE CONUS.

SHORT TERM...TODAY AND TOMORROW...
PATCHY FOG IN THE FORECAST FOR THE EARLY HOURS THIS MORNING AS
SOME LOCATIONS FLIRTING WITH SOME QUARTER MILE OBS OFF AND ON.
FRONT SHOULD MOVE THROUGH THE STATE TODAY...WITH SOME PRETTY
DECENT HEATING ON TAP FOR THE FAR SE. FRONT SHOULD EVENTUALLY MAKE
IT TO THE SE LATER THIS MORNING...AND POSSIBLY FIRE OFF ANOTHER
ROUND OF THUNDERSTORMS. HOW STRONG THE STORMS WILL BE AT THAT
POINT WILL DEPEND GREATLY ON HOW MUCH THE ATMOSPHERE WILL BE ABLE
TO RECHARGE. EITHER WAY...LOW CHANCE POPS SOUTH OF INTERSTATE 70
FOR THE REMAINDER OF THE MORNING. FORECAST DRIES OUT TONIGHT AND
THROUGH THE WEEKEND AS TEMPERATURES RETURN TO RATHER SEASONABLE
80S.

LONG TERM...SUNDAY THROUGH TUESDAY...
FORECAST DRY FOR THE FIRST FEW DAYS OF THE WORK WEEK. MOS GUIDANCE
STILL TERRIBLY AGGRESSIVE WITH A WARM UP AS IT HAS BEEN ALL
SUMMER. WITH A MODERATE AIRMASS BECOMING SOMEWHAT STAGNANT OVER
THE ERN HALF OF THE CONUS...WITH WEAK ERLY FLOW AT THE SFC...ONLY
BECOMING MORE SOUTHERLY ON DAY 5. KEEPING THE TEMPS IN THE
MID TO UPPER 80S RANGE THROUGH MUCH OF THE FORECAST...KNOCKING
SEVERAL DEGREES OFF OF MOS. MIDWEEK HOWEVER...A FRONT IS ON
APPROACH FROM THE NW...BRINGING THE NEXT CHANCE FOR PRECIP WEDNESDAY.

HJS


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 291732
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
640 AM CDT FRI AUG 29 2008

.DISCUSSION...
243 AM CDT

A COLD FRONT IS WORKING DOWN THRU IL AND IN THIS EARLY
MORNING...LOWERING DEWPTS AND SHUTTING OFF ANYMORE SHOWER
DEVELOPMENT. SHOWERS AND PSBL TSTMS LIKELY TO BE REDEVELOPING
AHEAD OF FRONT THRU THE NIGHTTIME HRS. MAY HAVE TO BEGIN EAST
SECTIONS WITH SCT RW/TSTMS TIL MID MRNG. CLOUD COVER DEBRIS FROM
MCS TO THE SOUTH IS DWINDLING IN TIME WITH FROPA ADVANCE. HIGH
DEWPT AIR AND CLEARING SKIES ALLOWING A BRIEF PERIOD OF DENSE FOG
BEFORE DRIER AIR IMPROVES CONDITIONS. IS DOUBTFUL ABOUT A FOG
ADVISORY SINCE DROP DOWN IN VSBY SO BRIEF. WILL MONITOR RATE OF
IMPROVEMENTS.

CLEARING SHUD SPREAD SE THRU FCST AREA THIS MRNG WITH CYCLONIC FLOW
EVIDENT IN SOUTH HALF TODAY. MAY SEE CU FORMATION THERE IN THE
AFTN. WITH RIDGING BUILDING IN TNGT AND SATURDAY...CLEAR SKIES
LIKELY TO CONTINUE. WE ARE NOT HAVING A STRONG EXTENDED COOLING
PERIOD LIKE LAST BOUT OF HIGH PRESSURE. INSTEAD WINDS RETURNING TO
SOUTH SAT NGT AND SUNDAY. LIKELY TO START A WARMUP TO NEAR 90 IN
PARTS OF NRN ILLINOIS LATE IN THE WEEKEND THAT CONTINUES THRU
TUESDAY.

NEXT CHC FOR RAIN COMING WED WITH THE SOUTH FLOW TAPPING SOME GULF
MSTR UP THRU THE PLAINS. THE INCREASED CLOUD COVER AT LEAST WILL
CURB THE DAILY CLIMB FROM REACHING TO 90. RAINFALL AND RISING DEWPTS
WILL DAMPEN THE HEAT EVEN FURTHER. DEWPTS IN THE 60S RETURN AND
HUMIDITY WILL STILL MAINTAIN SOME DISCOMFORT. QUESTIONS HOWEVER
RESIDE WITH THE INFLUENCE OF GUSTAV MAKING LANDFALL AROUND THAT
TIME. ITS LOCATION IN THE LOWER MS VLY MAY INHIBIT NORTHWARD
PROGRESS OF GULF MSTR FOR SOME TIME. THUS THE RAIN CHANCES PRESENTLY
FCST FOR THE AREA WED INTO THURSDAY MAY BE SMALL CHANCES UNTIL
GUSTAVS INTENSITY DECLINES AND LOOSENS ITS GRIP ON AVAILABLE
MOISTURE FOR THE MID AND UPR MS VLY.

RLB

&&

.AVIATION...DISCUSSION REGARDING 18Z TAFS...
1230 PM CDT

SFC HI PRESSURE CENTER OVR SWRN IA WILL BUILD EWD ACROSS NRN IL AND
NWRN IND TNGT AND SATURDAY.  IN ADDITION...UPR LVL RIDGING OVR MO
VLY WILL ALSO BUILD AS IT SHIFTS EWD OVR OH VLY AND WRN GRTLKS DURG
TAF PERIOD.  THIS SET UP IS EXPECTED TO PROVIDE GENLY VFR CLR
CONDITIONS WITH SFC DEW POINTS REMAINING IN 50S AND UPR RIDGE
PROVIDING INCRG SUBSIDENCE ALF.  ONLY CHG GROUPS IN TAFS DUE TO CHGS
IN WIND VELOCITY...ESPECIALLY INVOF LK MI WHERE LGT...MAINLY NWLY
WINDS WILL TURN MORE ONSHORE BY 20Z.  WINDS TO GO BACK TO VRBL AOB 5
KTS THIS EVENING AND REMAIN THAT WAY THRU 18Z SAT AS SFC HI SETTLES
OVHD.

MERZLOCK

&&

.MARINE...DISCUSSION REGARDING AFTERNOON FORECAST ISSUANCE...

1230 PM CDT

A WEAK COLD FRONT EXTENDS FROM HUDSON BAY...SOUTHWARD
ACROSS LAKE HURON AND THE LOWER OHIO VALLEY. THIS FRONT WILL
CONTINUE TO PUSH EASTWARD THIS AFTERNOON AS A SPRAWLING HIGH
PRESSURE INCHES BUILDS ACROSS THE MIDDLE AND UPPER MISSISSIPPI
VALLEY TONIGHT...AND SETTLES ACROSS THE SOUTHERN GREAT LAKES ON
SATURDAY.  AS A RESULT...WINDS ACROSS LAKE MICHIGAN WILL REMAIN
GENERALLY LIGHT. GIVEN WEAK PRESSURE GRADIENT...EXPECT THAT
PREVAILING NORTHERLY WIND FLOW TODAY WILL BECOME VARIABLE
TONIGHT...DOMINATED MORE BY LOCAL LAND/SEA BREEZES.

THE HIGH WILL CONTINUE ON ACROSS THE LOWER LAKES ON SUNDAY AS
A LOW PRESSURE DEVELOPS OVER THE NORTHERN ROCKIES AND MOVES OUT
ACROSS THE NORTHERN PLAINS ON SUNDAY. THE HIGH WILL REMAIN
NEARLY STATIONARY OVER THE EASTERN LAKES THROUGH MONDAY AS THE
PLAINS LOW TRACKS NORTHEAST INTO SOUTHERN ONTARIO.  THIS WILL
GRADUALLY BUILD SOUTH TO SOUTHWEST FLOW ACROSS THE WESTERN GREAT
LAKES HEADING INTO EARLY NEX WEEK.

MERZLOCK

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KILX 291529
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1029 AM CDT FRI AUG 29 2008

.DISCUSSION...
ISSUED 1028 AM CDT FRI AUG 29 2008

MORNING SURFACE ANALYSIS SHOWS COLD FRONT SINKING SOUTHWARD INTO
THE OHIO VALLEY...WHILE DRIER AIRMASS SLOWLY FILTERS INTO CENTRAL
ILLINOIS FROM THE NORTH. SURFACE DEWPOINTS ARE STILL HOLDING IN THE
UPPER 60S AND LOWER 70S ACROSS THE KILX CWA...WHILE MUCH DRIER 50S
DEWPOINTS REMAIN FURTHER TO THE N/NW ACROSS IOWA AND WISCONSIN.
WITH ONLY WEAK NORTHERLY FLOW EXPECTED TODAY...HAVE UPDATED HOURLY
DEWPOINT GRIDS TO FEATURE A MUCH SLOWER INTRODUCTION OF DRIER AIR
INTO THE AREA TODAY. BASED ON CURRENT TRENDS...IT APPEARS THE
HUMID CONDITIONS WILL STICK AROUND INTO THE AFTERNOON...BEFORE
MUCH MORE COMFORTABLE AIR SETTLES IN THIS EVENING AND OVERNIGHT.
HAVE ALSO TRIMMED THE LOW CHANCE POPS ACROSS THE E/SE CWA...WITH
ONLY A 20 POP ALONG AND SOUTH OF I-70 IN CLOSER PROXIMITY TO THE
DEPARTING FRONT. HIGH TEMP FORECAST LOOKS PRETTY MUCH ON
TARGET...WITH AFTERNOON READINGS MAINLY IN THE LOWER TO MIDDLE
80S. HAVE SENT OUT AN UPDATED ZONE PACKAGE TO REFLECT THESE
CHANGES.

BARNES
&&

.AVIATION...
ISSUED 640 AM CDT FRI AUG 29 2008

A COUPLE HOURS OF MAINLY MVFR/IFR CONDITIONS EXPECTED EARLY THIS
MORNING UNTIL FOG/STRATUS CAN BURN OFF. OTHERWISE...HIGH PRESSURE
WILL BUILD INTO THE REGION THROUGH THE PERIOD...WITH THE
ASSOCIATED DRIER AIRMASS...AND PROVIDE QUIET/VFR CONDITIONS.

BAK
&&

.PREV DISCUSSION...
ISSUED 258 AM CDT FRI AUG 29 2008
MASS OF THUNDERSTORMS SPLIT IN THE EVENING HOURS...WITH MOST OF
THE RAIN AND SEVERE WEATHER MOVING SW AND NORTH OF THE FA. ACTUAL
FRONTAL BOUNDARY HANGING BACK A BIT AS REMNANTS OF PRECIP MOVE OUT
OF THE CWA THIS MORNING. FRONT LOCATED ALONG AND JUST SE OF THE
ILLINOIS RIVER VALLEY AT FORECAST TIME. SOME PATCHY FOG DEVELOPING
TO THE WEST...AS WELL AS BEHIND THE SFC BOUNDARY WITH ALL OF THE
LLVL MOISTURE IN PLACE AFTER THE RAINFALL. NOT A LOT OF CHANGE AT
ALL TO THE FORECAST. FIRST CHALLENGE WILL BE THIS AFTERNOON IN THE
FAR SERN PART OF THE STATE AND ALONG THE OHIO RIVER VALLEY. ONLY
OTHER CHALLENGE AT THIS POINT IS TEMPERATURES AS A RIDGE BUILDS
OVER THE ERN HALF OF THE CONUS.

SHORT TERM...TODAY AND TOMORROW...
PATCHY FOG IN THE FORECAST FOR THE EARLY HOURS THIS MORNING AS
SOME LOCATIONS FLIRTING WITH SOME QUARTER MILE OBS OFF AND ON.
FRONT SHOULD MOVE THROUGH THE STATE TODAY...WITH SOME PRETTY
DECENT HEATING ON TAP FOR THE FAR SE. FRONT SHOULD EVENTUALLY MAKE
IT TO THE SE LATER THIS MORNING...AND POSSIBLY FIRE OFF ANOTHER
ROUND OF THUNDERSTORMS. HOW STRONG THE STORMS WILL BE AT THAT
POINT WILL DEPEND GREATLY ON HOW MUCH THE ATMOSPHERE WILL BE ABLE
TO RECHARGE. EITHER WAY...LOW CHANCE POPS SOUTH OF INTERSTATE 70
FOR THE REMAINDER OF THE MORNING. FORECAST DRIES OUT TONIGHT AND
THROUGH THE WEEKEND AS TEMPERATURES RETURN TO RATHER SEASONABLE
80S.

LONG TERM...SUNDAY THROUGH TUESDAY...
FORECAST DRY FOR THE FIRST FEW DAYS OF THE WORK WEEK. MOS GUIDANCE
STILL TERRIBLY AGGRESSIVE WITH A WARM UP AS IT HAS BEEN ALL
SUMMER. WITH A MODERATE AIRMASS BECOMING SOMEWHAT STAGNANT OVER
THE ERN HALF OF THE CONUS...WITH WEAK ERLY FLOW AT THE SFC...ONLY
BECOMING MORE SOUTHERLY ON DAY 5. KEEPING THE TEMPS IN THE
MID TO UPPER 80S RANGE THROUGH MUCH OF THE FORECAST...KNOCKING
SEVERAL DEGREES OFF OF MOS. MIDWEEK HOWEVER...A FRONT IS ON
APPROACH FROM THE NW...BRINGING THE NEXT CHANCE FOR PRECIP WEDNESDAY.

HJS

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KILX 291140
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
640 AM CDT FRI AUG 29 2008

.DISCUSSION...
ISSUED 258 AM CDT FRI AUG 29 2008
MASS OF THUNDERSTORMS SPLIT IN THE EVENING HOURS...WITH MOST OF
THE RAIN AND SEVERE WEATHER MOVING SW AND NORTH OF THE FA. ACTUAL
FRONTAL BOUNDARY HANGING BACK A BIT AS REMNANTS OF PRECIP MOVE OUT
OF THE CWA THIS MORNING. FRONT LOCATED ALONG AND JUST SE OF THE
ILLINOIS RIVER VALLEY AT FORECAST TIME. SOME PATCHY FOG DEVELOPING
TO THE WEST...AS WELL AS BEHIND THE SFC BOUNDARY WITH ALL OF THE
LLVL MOISTURE IN PLACE AFTER THE RAINFALL. NOT A LOT OF CHANGE AT
ALL TO THE FORECAST. FIRST CHALLENGE WILL BE THIS AFTERNOON IN THE
FAR SERN PART OF THE STATE AND ALONG THE OHIO RIVER VALLEY. ONLY
OTHER CHALLENGE AT THIS POINT IS TEMPERATURES AS A RIDGE BUILDS
OVER THE ERN HALF OF THE CONUS.

SHORT TERM...TODAY AND TOMORROW...
PATCHY FOG IN THE FORECAST FOR THE EARLY HOURS THIS MORNING AS
SOME LOCATIONS FLIRTING WITH SOME QUARTER MILE OBS OFF AND ON.
FRONT SHOULD MOVE THROUGH THE STATE TODAY...WITH SOME PRETTY
DECENT HEATING ON TAP FOR THE FAR SE. FRONT SHOULD EVENTUALLY MAKE
IT TO THE SE LATER THIS MORNING...AND POSSIBLY FIRE OFF ANOTHER
ROUND OF THUNDERSTORMS. HOW STRONG THE STORMS WILL BE AT THAT
POINT WILL DEPEND GREATLY ON HOW MUCH THE ATMOSPHERE WILL BE ABLE
TO RECHARGE. EITHER WAY...LOW CHANCE POPS SOUTH OF INTERSTATE 70
FOR THE REMAINDER OF THE MORNING. FORECAST DRIES OUT TONIGHT AND
THROUGH THE WEEKEND AS TEMPERATURES RETURN TO RATHER SEASONABLE
80S.

LONG TERM...SUNDAY THROUGH TUESDAY...
FORECAST DRY FOR THE FIRST FEW DAYS OF THE WORK WEEK. MOS GUIDANCE
STILL TERRIBLY AGGRESSIVE WITH A WARM UP AS IT HAS BEEN ALL
SUMMER. WITH A MODERATE AIRMASS BECOMING SOMEWHAT STAGNANT OVER
THE ERN HALF OF THE CONUS...WITH WEAK ERLY FLOW AT THE SFC...ONLY
BECOMING MORE SOUTHERLY ON DAY 5. KEEPING THE TEMPS IN THE
MID TO UPPER 80S RANGE THROUGH MUCH OF THE FORECAST...KNOCKING
SEVERAL DEGREES OFF OF MOS. MIDWEEK HOWEVER...A FRONT IS ON
APPROACH FROM THE NW...BRINGING THE NEXT CHANCE FOR PRECIP WEDNESDAY.

HJS
&&

.AVIATION...
ISSUED 640 AM CDT FRI AUG 29 2008

A COUPLE HOURS OF MAINLY MVFR/IFR CONDITIONS EXPECTED EARLY THIS
MORNING UNTIL FOG/STRATUS CAN BURN OFF. OTHERWISE...HIGH PRESSURE
WILL BUILD INTO THE REGION THROUGH THE PERIOD...WITH THE
ASSOCIATED DRIER AIRMASS...AND PROVIDE QUIET/VFR CONDITIONS.

BAK
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 291140
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
640 AM CDT FRI AUG 29 2008

.DISCUSSION...
243 AM CDT

A COLD FRONT IS WORKING DOWN THRU IL AND IN THIS EARLY
MORNING...LOWERING DEWPTS AND SHUTTING OFF ANYMORE SHOWER
DEVELOPMENT. SHOWERS AND PSBL TSTMS LIKELY TO BE REDEVELOPING
AHEAD OF FRONT THRU THE NIGHTTIME HRS. MAY HAVE TO BEGIN EAST
SECTIONS WITH SCT RW/TSTMS TIL MID MRNG. CLOUD COVER DEBRIS FROM
MCS TO THE SOUTH IS DWINDLING IN TIME WITH FROPA ADVANCE. HIGH
DEWPT AIR AND CLEARING SKIES ALLOWING A BRIEF PERIOD OF DENSE FOG
BEFORE DRIER AIR IMPROVES CONDITIONS. IS DOUBTFUL ABOUT A FOG
ADVISORY SINCE DROP DOWN IN VSBY SO BRIEF. WILL MONITOR RATE OF
IMPROVEMENTS.

CLEARING SHUD SPREAD SE THRU FCST AREA THIS MRNG WITH CYCLONIC FLOW
EVIDENT IN SOUTH HALF TODAY. MAY SEE CU FORMATION THERE IN THE
AFTN. WITH RIDGING BUILDING IN TNGT AND SATURDAY...CLEAR SKIES
LIKELY TO CONTINUE. WE ARE NOT HAVING A STRONG EXTENDED COOLING
PERIOD LIKE LAST BOUT OF HIGH PRESSURE. INSTEAD WINDS RETURNING TO
SOUTH SAT NGT AND SUNDAY. LIKELY TO START A WARMUP TO NEAR 90 IN
PARTS OF NRN ILLINOIS LATE IN THE WEEKEND THAT CONTINUES THRU
TUESDAY.

NEXT CHC FOR RAIN COMING WED WITH THE SOUTH FLOW TAPPING SOME GULF
MSTR UP THRU THE PLAINS. THE INCREASED CLOUD COVER AT LEAST WILL
CURB THE DAILY CLIMB FROM REACHING TO 90. RAINFALL AND RISING DEWPTS
WILL DAMPEN THE HEAT EVEN FURTHER. DEWPTS IN THE 60S RETURN AND
HUMIDITY WILL STILL MAINTAIN SOME DISCOMFORT. QUESTIONS HOWEVER
RESIDE WITH THE INFLUENCE OF GUSTAV MAKING LANDFALL AROUND THAT
TIME. ITS LOCATION IN THE LOWER MS VLY MAY INHIBIT NORTHWARD
PROGRESS OF GULF MSTR FOR SOME TIME. THUS THE RAIN CHANCES PRESENTLY
FCST FOR THE AREA WED INTO THURSDAY MAY BE SMALL CHANCES UNTIL
GUSTAVS INTENSITY DECLINES AND LOOSENS ITS GRIP ON AVAILABLE
MOISTURE FOR THE MID AND UPR MS VLY.

RLB

&&

.AVIATION...
715 PM CDT

12Z TAFS...MAIN CONCERN FOR THE MORNING HOURS WILL BE HOW FAST THE
RESIDUAL BR/HZ WILL LIFT AT RFD/DPA. ORD/MDW ONLY BRIEFLY DROPPED
TO MVFR OVERNIGHT...BUT DUE TO THE GREATER HEAT ISLAND EFFECTS AT
THESE SITES...DID NOT DROP ANY LOWER. LATEST SFC OBS SHOW DRIER
AIR IS FILTERING OVER NRN IL BEHIND A VERY DIFFUSE FRONTAL
PASSAGE. THE TRENDS AT ALL SITES ARE TO QUICKLY IMPROVE CIGS/VIS
AND EXPECT ALL SITE TO GO VFR...AND EVEN SKC...BY 13Z. THE
REMAINDER OF THE DAY SHOULD BE QUIET FOR AVIATION WEATHER
CONCERNS. THE ONLY OTHER QUESTION FOR THE DAY WILL BE WIND SPEEDS.
WITH THE SFC RIDGE AXIS POKING OVER SRN WISCONSIN...EXPECT THAT
WINDS WILL VEER FROM NLY TO NELY BY ARND 18Z. THE SFC RIDGE WILL
THEN SINK SWD THIS EVENING AND EXPECT THAT WINDS WILL GO LGT/VRBL
DURG THE EARLY EVENING HOURS. HOWEVER...DESPITE CLEAR SKIES AND
LIGHT WINDS...DO NOT EXPECT ANY VISBY RESTRICTIONS TONIGHT AS THE
AIRMASS WILL DRY OUT CONSIDERABLY...WITH SFC DEWPOINTS EXPECTED TO
DROP INTO THE UPPER 40S OR LOW 50S OVERNIGHT TONIGHT.

KREIN

&&

.MARINE...

245 PM CDT

A WEAK COLD FRONT EXTENDS SOUTH FROM HUDSON BAY INTO WESTERN LOWER
MICHIGAN TO THE MIDDLE MISSISSIPPI VALLEY AND CENTRAL PLAINS. THIS
FRONT WILL CONTINUE TO PUSH EASTWARD TODAY AS HIGH PRESSURE BUILDS
OVER THE MIDDLE AND UPPER MISSISSIPPI VALLEY AND THE WESTERN GREAT
LAKES. THE HIGH WILL CONTINUE TO BUILD EAST INTO THE EASTERN GREAT
LAKES SUNDAY. MEANWHILE...A NEW LOW PRESSURE SYSTEM IS FORECAST TO
DEVELOP OVER THE NORTHERN ROCKIES SATURDAY NIGHT AND MOVE OUT OVER
THE NORTHERN PLAINS ON SUNDAY. THE HIGH WILL REMAIN NEARLY
STATIONARY OVER THE EASTERN LAKES THROUGH MONDAY AS THE PLAINS LOW
TRACKS NORTHEAST INTO SOUTHERN ONTARIO.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KILX 290818
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
318 AM CDT FRI AUG 29 2008

.DISCUSSION...
ISSUED 258 AM CDT FRI AUG 29 2008
MASS OF THUNDERSTORMS SPLIT IN THE EVENING HOURS...WITH MOST OF
THE RAIN AND SEVERE WEATHER MOVING SW AND NORTH OF THE FA. ACTUAL
FRONTAL BOUNDARY HANGING BACK A BIT AS REMNANTS OF PRECIP MOVE OUT
OF THE CWA THIS MORNING. FRONT LOCATED ALONG AND JUST SE OF THE
ILLINOIS RIVER VALLEY AT FORECAST TIME. SOME PATCHY FOG DEVELOPING
TO THE WEST...AS WELL AS BEHIND THE SFC BOUNDARY WITH ALL OF THE
LLVL MOISTURE IN PLACE AFTER THE RAINFALL. NOT A LOT OF CHANGE AT
ALL TO THE FORECAST. FIRST CHALLENGE WILL BE THIS AFTERNOON IN THE
FAR SERN PART OF THE STATE AND ALONG THE OHIO RIVER VALLEY. ONLY
OTHER CHALLENGE AT THIS POINT IS TEMPERATURES AS A RIDGE BUILDS
OVER THE ERN HALF OF THE CONUS.

SHORT TERM...TODAY AND TOMORROW...
PATCHY FOG IN THE FORECAST FOR THE EARLY HOURS THIS MORNING AS
SOME LOCATIONS FLIRTING WITH SOME QUARTER MILE OBS OFF AND ON.
FRONT SHOULD MOVE THROUGH THE STATE TODAY...WITH SOME PRETTY
DECENT HEATING ON TAP FOR THE FAR SE. FRONT SHOULD EVENTUALLY MAKE
IT TO THE SE LATER THIS MORNING...AND POSSIBLY FIRE OFF ANOTHER
ROUND OF THUNDERSTORMS. HOW STRONG THE STORMS WILL BE AT THAT
POINT WILL DEPEND GREATLY ON HOW MUCH THE ATMOSPHERE WILL BE ABLE
TO RECHARGE. EITHER WAY...LOW CHANCE POPS SOUTH OF INTERSTATE 70
FOR THE REMAINDER OF THE MORNING. FORECAST DRIES OUT TONIGHT AND
THROUGH THE WEEKEND AS TEMPERATURES RETURN TO RATHER SEASONABLE
80S.

LONG TERM...SUNDAY THROUGH TUESDAY...
FORECAST DRY FOR THE FIRST FEW DAYS OF THE WORK WEEK. MOS GUIDANCE
STILL TERRIBLY AGGRESSIVE WITH A WARM UP AS IT HAS BEEN ALL
SUMMER. WITH A MODERATE AIRMASS BECOMING SOMEWHAT STAGNANT OVER
THE ERN HALF OF THE CONUS...WITH WEAK ERLY FLOW AT THE SFC...ONLY
BECOMING MORE SOUTHERLY ON DAY 5. KEEPING THE TEMPS IN THE
MID TO UPPER 80S RANGE THROUGH MUCH OF THE FORECAST...KNOCKING
SEVERAL DEGREES OFF OF MOS. MIDWEEK HOWEVER...A FRONT IS ON
APPROACH FROM THE NW...BRINGING THE NEXT CHANCE FOR PRECIP WEDNESDAY.

HJS
&&

.AVIATION...
ISSUED 1134 PM CDT THU AUG 28 2008...FOR THE 06Z TAFS

THE LINE OF STORMS HAS REACHED CMI...WITH SOME CLEARING TRYING TO
WORK ITS WAY IN FROM THE NW. A FEW STORMS MAY DEVELOP FOR THE NEXT
FEW HOURS BEHIND THE STRATIFORM RAINS...BUT DO NOT EXPECT MUCH IN
THE WAY OF COVERAGE. WILL KEEP SOME VCTS AND VCSH FOR ALL BUT
PIA...THEN FOG BECOMES THE MAIN ISSUE. I WENT WITH VLIFR FOR BMI
AND CMI...WITH JUST IFR EVERYWHERE ELSE. FORECAST SOUNDINGS AND
UPS FOG OUTPUT INDICATE AREAS OF FOG SHOULD DEVELOP IN THE HIGHER
DEWPOINT AIR. THE LOWER DEWPOINTS ARE LAGGING WELL BACK TO THE
NW...SO FOG IS A GOOD BET ONCE SKIES BEGIN TO CLEAR OUT A BIT.

AFTER THAT...A DRY NORTH FLOW SHOULD PROVIDE QUIET WEATHER THE
REST OF THE TAF PERIOD. THE AIR SHOULD BE DRY ENOUGH FRIDAY NIGHT
FOR LITTLE IF ANY FOG.

SHIMON
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 290803
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
303 AM CDT FRI AUG 29 2008

.DISCUSSION...
243 AM CDT

A COLD FRONT IS WORKING DOWN THRU IL AND IN THIS EARLY
MORNING...LOWERING DEWPTS AND SHUTTING OFF ANYMORE SHOWER
DEVELOPMENT. SHOWERS AND PSBL TSTMS LIKELY TO BE REDEVELOPING
AHEAD OF FRONT THRU THE NIGHTIME HRS. MAY HAVE TO BEGIN EAST
SECTIONS WITH SCT RW/TSTMS TIL MID MRNG. CLOUD COVER DEBRIS FROM
MCS TO THE SOUTH IS DWINDLING IN TIME WITH FROPA ADVANCE. HIGH
DEWPT AIR AND CLEARING SKIES ALLOWING A BRIEF PERIOD OF DENSE FOG
BEFORE DRIER AIR IMPROVES CONDITIONS. IS DOUBTFUL ABOUT A FOG
ADVISORY SINCE DROP DOWN IN VSBY SO BRIEF. WILL MONITOR RATE OF
IMPROVEMENTS.

CLEARING SHUD SPREAD SE THRU FCST AREA THIS MRNG WITH CYCLONIC FLOW
EVIDENT IN SOUTH HALF TODAY. MAY SEE CU FORMATION THERE IN THE
AFTN. WITH RIDGING BUILDING IN TNGT AND SATURDAY...CLEAR SKIES
LIKELY TO CONTINUE. WE ARE NOT HAVING A STRONG EXTENDED COOLING
PERIOD LIKE LAST BOUT OF HIGH PRESSURE. INSTEAD WINDS RETURNING TO
SOUTH SAT NGT AND SUNDAY. LIKELY TO START A WARMUP TO NEAR 90 IN
PARTS OF NRN ILLINOIS LATE IN THE WEEKEND THAT CONTINUES THRU
TUESDAY.

NEXT CHC FOR RAIN COMING WED WITH THE SOUTH FLOW TAPPING SOME GULF
MSTR UP THRU THE PLAINS. THE INCREASED CLOUD COVER AT LEAST WILL
CURB THE DAILY CLIMB FROM REACHING TO 90. RAINFALL AND RISING DEWPTS
WILL DAMPEN THE HEAT EVEN FURTHER. DEWPTS IN THE 60S RETURN AND
HUMIDITY WILL STILL MAINTAIN SOME DISCOMFORT. QUESTIONS HOWEVER
RESIDE WITH THE INFLUENCE OF GUSTAV MAKING LANDFALL AROUND THAT
TIME. ITS LOCATION IN THE LOWER MS VLY MAY INHIBIT NORTHWARD
PROGRESS OF GULF MSTR FOR SOME TIME. THUS THE RAIN CHANCES PRESENTLY
FCST FOR THE AREA WED INTO THURSDAY MAY BE SMALL CHANCES UNTIL
GUSTAVS INTENSITY DECLINES AND LOOSENS ITS GRIP ON AVAILABLE
MOISTURE FOR THE MID AND UPR MS VLY.

RLB

&&

.AVIATION...
715 PM CDT

06Z TAFS...MAIN CONCERN FOR THE OVERNIGHT HOURS WILL FOCUS ON
CIGS/VIS. ONGOING THUNDER FROM THE MCS THAT DEVELOPED EARLIER THIS
EVENING WILL REMAIN WELL SOUTH OF THE TERMINALS. THE COLD FRONT
CONTINUES TO SAG SEWD THROUGH SRN WI AND SHOULD MOVE INTO NRN IL
BY ARND 06-07Z. HIGH DEWPOINT...UPPER 60S-LOW 70S...HAVE POOLED
AHEAD OF THE FRONT AND WITH A VERY WEAK PRESSURE
GRADIENT...CEILINGS AND VISIBITY HAVE DROPPED INTO MVFR AND IFR AT
LOCATIONS JUST AHEAD OF THE FRONT. WITH THE FRONTAL
PASSAGE...DRIER AIR WILL RAPIDLY FILTER IN AND CONDITIONS SHOULD
QUICKLY IMPROVE TO VFR...AND HAVE TIMED OUT THE IMPROVEMENT TO
OCCUR SHORTLY BEFORE SUNRISE. THE REMAINDER OF THE DAYS SHOULD SEE
VFR CONDITIONS WITH CLEAR SKIES. WINDS SHOULD GRADUALLY VEER TO
NELY DURG THE AFTERNOON AS A RIDGE OF HIGH PRESSURE BUILDS OVER
SRN WI.

KREIN

&&

.MARINE...

245 PM CDT

A WEAK COLD FRONT EXTENDS SOUTH FROM HUDSON BAY INTO WESTERN LOWER
MICHIGAN TO THE MIDDLE MISSISSIPPI VALLEY AND CENTRAL PLAINS. THIS
FRONT WILL CONTINUE TO PUSH EASTWARD TODAY AS HIGH PRESSURE BUILDS
OVER THE MIDDLE AND UPPER MISSISSIPPI VALLEY AND THE WESTERN GREAT
LAKES. THE HIGH WILL CONTINUE TO BUILD EAST INTO THE EASTERN GREAT
LAKES SUNDAY. MEANWHILE...A NEW LOW PRESSURE SYSTEM IS FORECAST TO
DEVELOP OVER THE NORTHERN ROCKIES SATURDAY NIGHT AND MOVE OUT OVER
THE NORTHERN PLAINS ON SUNDAY. THE HIGH WILL REMAIN NEARLY
STATIONARY OVER THE EASTERN LAKES THROUGH MONDAY AS THE PLAINS LOW
TRACKS NORTHEAST INTO SOUTHERN ONTARIO.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KLOT 290745
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
245 AM CDT FRI AUG 29 2008

.DISCUSSION...
243 AM CDT

A COLD FRONT IS WORKING DOWN THRU IL AND IN THIS EARLY
MORNING...LOWERING DEWPTS AND SHUTTING OFF ANYMORE SHOWER
DEVELOPMENT. SHOWERS AND PSBL TSTMS LIKELY TO BE REDEVELOPING
AHEAD OF FRONT THRU THE NIGHTIME HRS. MAY HAVE TO BEGIN EAST
SECTIONS WITH SCT RW/TSTMS TIL MID MRNG. CLOUD COVER DEBRIS FROM
MCS TO THE SOUTH IS DWINDLING IN TIME WITH FROPA ADVANCE. HIGH
DEWPT AIR AND CLEARING SKIES ALLOWING A BRIEF PERIOD OF DENSE FOG
BEFORE DRIER AIR IMPROVES CONDITIONS. IS DOUBTFUL ABOUT A FOG
ADVISORY SINCE DROP DOWN IN VSBY SO BRIEF. WILL MONITOR RATE OF
IMPROVEMENTS.

CLEARING SHUD SPREAD SE THRU FCST AREA THIS MRNG WITH CYCLONIC FLOW
EVIDENT IN SOUTH HALF TODAY. MAY SEE CU FORMATION THERE IN THE
AFTN. WITH RIDGING BUILDING IN TNGT AND SATURDAY...CLEAR SKIES
LIKELY TO CONTINUE. WE ARE NOT HAVING A STRONG EXTENDED COOLING
PERIOD LIKE LAST BOUT OF HIGH PRESSURE. INSTEAD WINDS RETURNING TO
SOUTH SAT NGT AND SUNDAY. LIKELY TO START A WARMUP TO NEAR 90 IN
PARTS OF NRN ILLINOIS LATE IN THE WEEKEND THAT CONTINUES THRU
TUESDAY.

NEXT CHC FOR RAIN COMING WED WITH THE SOUTH FLOW TAPPING SOME GULF
MSTR UP THRU THE PLAINS. THE INCREASED CLOUD COVER AT LEAST WILL
CURB THE DAILY CLIMB FROM REACHING TO 90. RAINFALL AND RISING DEWPTS
WILL DAMPEN THE HEAT EVEN FURTHER. DEWPTS IN THE 60S RETURN AND
HUMIDITY WILL STILL MAINTAIN SOME DISCOMFORT. QUESTIONS HOWEVER
RESIDE WITH THE INFLUENCE OF GUSTAV MAKING LANDFALL AROUND THAT
TIME. ITS LOCATION IN THE LOWER MS VLY MAY INHIBIT NORTHWARD
PROGRESS OF GULF MSTR FOR SOME TIME. THUS THE RAIN CHANCES PRESENTLY
FCST FOR THE AREA WED INTO THURSDAY MAY BE SMALL CHANCES UNTIL
GUSTAVS INTENSITY DECLINES AND LOOSENS ITS GRIP ON AVAILABLE
MOISTURE FOR THE MID AND UPR MS VLY.

RLB

&&

.AVIATION...
715 PM CDT

06Z TAFS...MAIN CONCERN FOR THE OVERNIGHT HOURS WILL FOCUS ON
CIGS/VIS. ONGOING THUNDER FROM THE MCS THAT DEVELOPED EARLIER THIS
EVENING WILL REMAIN WELL SOUTH OF THE TERMINALS. THE COLD FRONT
CONTINUES TO SAG SEWD THROUGH SRN WI AND SHOULD MOVE INTO NRN IL
BY ARND 06-07Z. HIGH DEWPOINT...UPPER 60S-LOW 70S...HAVE POOLED
AHEAD OF THE FRONT AND WITH A VERY WEAK PRESSURE
GRADIENT...CEILINGS AND VISIBITY HAVE DROPPED INTO MVFR AND IFR AT
LOCATIONS JUST AHEAD OF THE FRONT. WITH THE FRONTAL
PASSAGE...DRIER AIR WILL RAPIDLY FILTER IN AND CONDITIONS SHOULD
QUICKLY IMPROVE TO VFR...AND HAVE TIMED OUT THE IMPROVEMENT TO
OCCUR SHORTLY BEFORE SUNRISE. THE REMAINDER OF THE DAYS SHOULD SEE
VFR CONDITIONS WITH CLEAR SKIES. WINDS SHOULD GRADUALLY VEER TO
NELY DURG THE AFTERNOON AS A RIDGE OF HIGH PRESSURE BUILDS OVER
SRN WI.

KREIN

&&

.MARINE...

245 PM CDT

A COLD FRONT WILL APPROACH LAKE MICHIGAN TONIGHT. THIS WILL GIVE A
WIND SHIFT FROM THE SOUTH TO NORTHWEST BY FRIDAY MORNING. BY
SATURDAY MORNING A HIGH WILL MOVE INTO THE REGION FROM IOWA TO
MICHIGAN. WE EXPECT THE WIND WILL BECOME LIGHT SATURDAY. HOWEVER
ON FRIDAY THERE WILL BE A WIND OF 15 TO 20 KNOTS. THIS MAY PRODUCE
SOME SIGNIFICANT WAVES OF 3 TO 5 FEET ON THE SOUTH HALF OF LAKE
MICHIGAN FRIDAY.

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KLOT 290552
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1252 AM CDT FRI AUG 29 2008

.DISCUSSION...
650 PM CDT

GRIDS/DERIVED PRODUCTS BEING UPDATED AT THIS TIME TO REMOVE
THUNDER FROM FORECAST FOR THIS EVENING OVER ALL BUT FAR SOUTHERN
CWA. VISIBLE SATELLITE IMAGERY SHOWS STRATUS DECK MOVING ACROSS CWA
WITH NO INDICATION OF ANY APPRECIABLE VERTICAL DEVELOPMENT IN THE
DECK. IR IMAGERY INDICATES CLOUD TOP TEMPS ALL ABOVE FREEZING...SO
NO ICE CRYSTALS IN CLOUDINESS SHOULD RESULT IN WARM RAIN PROCESSES
AND GENERALLY SMALL DROPLET DIAMETER WITH ANY PRECIP THAT FALLS
FROM THIS DECK. GIVEN THIS AND PRONOUNCED CAP EVIDENT IN RECENT
ACARS SOUNDINGS HAVE JUST GONE WITH LIGHT RAIN/DRIZZLE THIS
EVENING OVER ALL BUT FAR SOUTHERN CWA WHERE SOME WEAK INSTABILITY
MAY BE PRESENT GIVEN CHARACTER OF CLOUDINESS ON VIS IMAGERY.

FARTHER NW...CLOSER TO THE FRONT...NARROW LINE OF
SHOWERS/THUNDERSTORMS HAVE DEVELOPED OVER CENTRAL WISCONSIN. WOULD
FULLY EXPECT THAT WITH TIME AND LOSS OF INSOLATION THAT THESE
STORMS WILL DISSIPATE BEFORE MAKING IT INTO ILLINOIS...BUT GIVEN
THAT FORECAST ALREADY HAD MENTION OF THUNDER DECIDED TO RETAIN
THAT FOR NOW AFTER MIDNIGHT BUT WILL RE-ACCESS LATER THIS
EVENING...AT WHICH TIME THE WI CONVECTION WILL HOPEFULLY HAVE
TIPPED ITS HAND GIVING SOME INDICATION OF ITS PLANS FOR THE
OVERNIGHT HOURS.

UPDATED PRODUCTS ALREADY SHIPPED.

IZZI

&&

.AVIATION...
715 PM CDT

06Z TAFS...MAIN CONCERN FOR THE OVERNIGHT HOURS WILL FOCUS ON
CIGS/VIS. ONGOING THUNDER FROM THE MCS THAT DEVELOPED EARLIER THIS
EVENING WILL REMAIN WELL SOUTH OF THE TERMINALS. THE COLD FRONT
CONTINUES TO SAG SEWD THROUGH SRN WI AND SHOULD MOVE INTO NRN IL
BY ARND 06-07Z. HIGH DEWPOINT...UPPER 60S-LOW 70S...HAVE POOLED
AHEAD OF THE FRONT AND WITH A VERY WEAK PRESSURE
GRADIENT...CEILINGS AND VISIBITY HAVE DROPPED INTO MVFR AND IFR AT
LOCATIONS JUST AHEAD OF THE FRONT. WITH THE FRONTAL
PASSAGE...DRIER AIR WILL RAPIDLY FILTER IN AND CONDITIONS SHOULD
QUICKLY IMPROVE TO VFR...AND HAVE TIMED OUT THE IMPROVEMENT TO
OCCUR SHORTLY BEFORE SUNRISE. THE REMAINDER OF THE DAYS SHOULD SEE
VFR CONDITIONS WITH CLEAR SKIES. WINDS SHOULD GRADUALLY VEER TO
NELY DURG THE AFTERNOON AS A RIDGE OF HIGH PRESSURE BUILDS OVER
SRN WI.

KREIN

&&

.MARINE...

245 PM CDT

A COLD FRONT WILL APPROACH LAKE MICHIGAN TONIGHT. THIS WILL GIVE A
WIND SHIFT FROM THE SOUTH TO NORTHWEST BY FRIDAY MORNING. BY
SATURDAY MORNING A HIGH WILL MOVE INTO THE REGION FROM IOWA TO
MICHIGAN. WE EXPECT THE WIND WILL BECOME LIGHT SATURDAY. HOWEVER
ON FRIDAY THERE WILL BE A WIND OF 15 TO 20 KNOTS. THIS MAY PRODUCE
SOME SIGNIFICANT WAVES OF 3 TO 5 FEET ON THE SOUTH HALF OF LAKE
MICHIGAN FRIDAY.

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KILX 290434
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1134 PM CDT THU AUG 28 2008

.DISCUSSION...
ISSUED 859 PM CDT THU AUG 28 2008

STORMS ARE PROGRESSING SE ACROSS OUR CWA...BUT SHOULD PRIMARILY
AFFECT THE SW HALF OF THE CWA. HEAVY RAIN APPEARS TO BE THE MAIN
HAZARD FROM HEAR ON OUT. LOCALIZED FLOODING MOST LIKELY OCCURRED
WHERE RADAR ESTIMATES OF 3 TO 4 INCHES WHERE INDICATED. HAVE AN
URBAN AND SMALL STREAM FLOOD ADVISORY OUT FOR THE HEAVIEST
ESTIMATES. LSX RECEIVED A RAINFALL REPORT OF 3.5 INCHES IN MOUNT
STERLING...AND THAT MATCHED UP WELL WITH RADAR ESTIMATES.

FREQUENT LIGHTNING IS ALSO EXPECTED...ESPECIALLY FOR THE STORMS IN
CASS...MORGAN...AND SCOTT COUNTIES...HEADED FOR SANGAMON AND
CHRISTIAN COUNTIES. WILL EXPAND THE LIKELY POPS TO AFTER MIDNIGHT
FOR THE SOUTHERN CWA...AS THE TIMING NOW APPEARS TO BE SLOWER THAN
PREVIOUS ESTIMATES. NO OTHER MAJOR CHANGES TO THE GRIDS ARE
EXPECTED OVERNIGHT. WILL UPDATE FOR THE NEW AREA OF LIKELY
POPS...AND THEN WILL UPDATE AS WE CLEAR THE WATCH FROM WEST TO
EAST.

MOST LIKELY THE WATCH WILL BE CANCELLED BEFORE THE 1 AM ENDING TIME.

SHIMON

&&

.AVIATION...
ISSUED 1134 PM CDT THU AUG 28 2008...FOR THE 06Z TAFS

THE LINE OF STORMS HAS REACHED CMI...WITH SOME CLEARING TRYING TO
WORK ITS WAY IN FROM THE NW. A FEW STORMS MAY DEVELOP FOR THE NEXT
FEW HOURS BEHIND THE STRATIFORM RAINS...BUT DO NOT EXPECT MUCH IN
THE WAY OF COVERAGE. WILL KEEP SOME VCTS AND VCSH FOR ALL BUT
PIA...THEN FOG BECOMES THE MAIN ISSUE. I WENT WITH VLIFR FOR BMI
AND CMI...WITH JUST IFR EVERYWHERE ELSE. FORECAST SOUNDINGS AND
UPS FOG OUTPUT INDICATE AREAS OF FOG SHOULD DEVELOP IN THE HIGHER
DEWPOINT AIR. THE LOWER DEWPOINTS ARE LAGGING WELL BACK TO THE
NW...SO FOG IS A GOOD BET ONCE SKIES BEGIN TO CLEAR OUT A BIT.

AFTER THAT...A DRY NORTH FLOW SHOULD PROVIDE QUIET WEATHER THE
REST OF THE TAF PERIOD. THE AIR SHOULD BE DRY ENOUGH FRIDAY NIGHT
FOR LITTLE IF ANY FOG.

SHIMON
&&

.PREV DISCUSSION...
ISSUED 714 PM CDT THU AUG 28 2008

DID A QUICK UPDATE TO THE GRIDS FOR LIKELY STORMS THIS EVENING IN
THE SW THIRD OF THE CWA. ADDED MENTION OF SEVERE STORMS WITH HAIL
AND WINDS FOR THE SEVERE THUNDERSTORM WATCH AREA AS WELL. WATCH IS
IN EFFECT UNTIL 06Z. THE STRONGEST PORTION OF THE BOW ECHO APPEARS
LIKE IT MAY CLIP SCOTT COUNTY. FARTHER TO THE NORTH AND EAST...THE
SEVERE THREAT WILL BE OF A SCATTERED NATURE AND PRIMARILY FOR
LARGE HAIL. LESS ORGANIZED DOWNBURSTS WILL STILL BE POSSIBLE IN
THAT AREA AS WELL.

UPDATED ZONES AND GRIDS ARE ALREADY AVAILABLE.

SHIMON


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KILX 290159
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
859 PM CDT THU AUG 28 2008

.DISCUSSION...
ISSUED 859 PM CDT THU AUG 28 2008

STORMS ARE PROGRESSING SE ACROSS OUR CWA...BUT SHOULD PRIMARILY
AFFECT THE SW HALF OF THE CWA. HEAVY RAIN APPEARS TO BE THE MAIN
HAZARD FROM HEAR ON OUT. LOCALIZED FLOODING MOST LIKELY OCCURRED
WHERE RADAR ESTIMATES OF 3 TO 4 INCHES WHERE INDICATED. HAVE AN
URBAN AND SMALL STREAM FLOOD ADVISORY OUT FOR THE HEAVIEST
ESTIMATES. LSX RECEIVED A RAINFALL REPORT OF 3.5 INCHES IN MOUNT
STERLING...AND THAT MATCHED UP WELL WITH RADAR ESTIMATES.

FREQUENT LIGHTNING IS ALSO EXPECTED...ESPECIALLY FOR THE STORMS IN
CASS...MORGAN...AND SCOTT COUNTIES...HEADED FOR SANGAMON AND
CHRISTIAN COUNTIES. WILL EXPAND THE LIKELY POPS TO AFTER MIDNIGHT
FOR THE SOUTHERN CWA...AS THE TIMING NOW APPEARS TO BE SLOWER THAN
PREVIOUS ESTIMATES. NO OTHER MAJOR CHANGES TO THE GRIDS ARE
EXPECTED OVERNIGHT. WILL UPDATE FOR THE NEW AREA OF LIKELY
POPS...AND THEN WILL UPDATE AS WE CLEAR THE WATCH FROM WEST TO
EAST.

MOST LIKELY THE WATCH WILL BE CANCELLED BEFORE THE 1 AM ENDING TIME.

SHIMON
&&

.AVIATION...
ISSUED 636 PM CDT THU AUG 28 2008...FOR THE 00Z TAFS

STORMS ARE DEVELOPING IN OUR W CWA...AHEAD OF THE MAIN MCS IN N
MO. THE STORM TRACKS APPEAR TO TAKE MOST OF THE ACTIVITY SOUTH OF
LINCOLN...WITH SPI IN THE PATH OF THE STRONGEST STORMS. HAVE HIT
SPI THE HARDEST WITH IFR VIS TO 1SM...+TSRA AND GUSTY WINDS BETWEEN
00Z AND 03Z. DEC MAY SEE SOME OF THAT...BUT AREAS N AND E OF SPI
WILL SEE MORE SCATTERED STORMS AND A BIT WEAKER. MAY BE SEEING A
SVR STORM WATCH SOON FOR OUR SW AREAS AS WELL.

DID NOT EXTEND THE VCTS IN THE TAFS MUCH BEYOND 06Z...BUT MAY NEED
TO ADJUST AS THE LINE PROGRESSES INTO OUR CWA.

FOG IS EXPECTED TO BECOME LOCALLY DENSE IN THE WAKE OF THESE
STORMS. CMI WILL HAVE A CHANCE FOR VLIFR VIS AGAIN...SINCE THE
LOWER DEWPOINT AIR IS LAGGING WELL BEHIND THIS LINE OF STORMS.
DEWPOINTS WILL LIKELY REMAIN AROUND 70 IN MUCH OF THE AREA THROUGH
MORNING. WILL KEEP AT LEAST IFR FOG IN A TEMPO FOR ALL SITES.

SHIMON
&&

.PREV DISCUSSION...
ISSUED 714 PM CDT THU AUG 28 2008

DID A QUICK UPDATE TO THE GRIDS FOR LIKELY STORMS THIS EVENING IN
THE SW THIRD OF THE CWA. ADDED MENTION OF SEVERE STORMS WITH HAIL
AND WINDS FOR THE SEVERE THUNDERSTORM WATCH AREA AS WELL. WATCH IS
IN EFFECT UNTIL 06Z. THE STRONGEST PORTION OF THE BOW ECHO APPEARS
LIKE IT MAY CLIP SCOTT COUNTY. FARTHER TO THE NORTH AND EAST...THE
SEVERE THREAT WILL BE OF A SCATTERED NATURE AND PRIMARILY FOR
LARGE HAIL. LESS ORGANIZED DOWNBURSTS WILL STILL BE POSSIBLE IN
THAT AREA AS WELL.

UPDATED ZONES AND GRIDS ARE ALREADY AVAILABLE.

SHIMON

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 290019
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
719 PM CDT THU AUG 28 2008

.DISCUSSION...
650 PM CDT

GRIDS/DERIVED PRODUCTS BEING UPDATED AT THIS TIME TO REMOVE
THUNDER FROM FORECAST FOR THIS EVENING OVER ALL BUT FAR SOUTHERN
CWA. VISIBLE SATELLITE IMAGERY SHOWS STRATUS DECK MOVING ACROSS CWA
WITH NO INDICATION OF ANY APPRECIABLE VERTICAL DEVELOPMENT IN THE
DECK. IR IMAGERY INDICATES CLOUD TOP TEMPS ALL ABOVE FREEZING...SO
NO ICE CRYSTALS IN CLOUDINESS SHOULD RESULT IN WARM RAIN PROCESSES
AND GENERALLY SMALL DROPLET DIAMETER WITH ANY PRECIP THAT FALLS
FROM THIS DECK. GIVEN THIS AND PRONOUNCED CAP EVIDENT IN RECENT
ACARS SOUNDINGS HAVE JUST GONE WITH LIGHT RAIN/DRIZZLE THIS
EVENING OVER ALL BUT FAR SOUTHERN CWA WHERE SOME WEAK INSTABILITY
MAY BE PRESENT GIVEN CHARACTER OF CLOUDINESS ON VIS IMAGERY.

FARTHER NW...CLOSER TO THE FRONT...NARROW LINE OF
SHOWERS/THUNDERSTORMS HAVE DEVELOPED OVER CENTRAL WISCONSIN. WOULD
FULLY EXPECT THAT WITH TIME AND LOSS OF INSOLATION THAT THESE
STORMS WILL DISSIPATE BEFORE MAKING IT INTO ILLINOIS...BUT GIVEN
THAT FORECAST ALREADY HAD MENTION OF THUNDER DECIDED TO RETAIN
THAT FOR NOW AFTER MIDNIGHT BUT WILL RE-ACCESS LATER THIS
EVENING...AT WHICH TIME THE WI CONVECTION WILL HOPEFULLY HAVE
TIPPED ITS HAND GIVING SOME INDICATION OF ITS PLANS FOR THE
OVERNIGHT HOURS.

UPDATED PRODUCTS ALREADY SHIPPED.

IZZI

&&

.AVIATION...

.AVIATION...
715 PM CDT

00Z TAFORS...FRONTAL BOUNDARY AT 23Z EXTENDS FROM EASTERN LK
SUPERIOR SOUTHWESTWARD SW WI AND ON TO NW MO. EXTENSIVE CLOUDINESS
DURING THE DAY FROM CENTRAL AND NORTHERN IL INTO SE WI...SW LOWER
MI AND NW IND HAS LIMITED HEATING AND THUS SURFACE BASED CAPE. IN
CONTRAST...TEMPERATURES CLIMBING INTO MID AND UPPER 80S WITH DEW
POINTS IN THE LOWER AND MID 70S ACROSS SE IA AND NORTHERN MO
RESULTED IN SB CAPES OF 3500-4500 J/KG. EXPECT ENLARGING AREA OF
TS IN THAT AREA TO SPREAD SOUTHEASTWARD ALONG WITH THE FRONT AS
THE SOUTHERN PORTION OF A MID LEVEL SHORT WAVE TROUGH CONTINUES TO
PUSH E ACROSS THE MID MS VALLEY.

A LINE OF SHRA AND SOME TS HAVE DEVELOPED EARLY THIS EVENING FROM
E CENTRAL TO SW WI WHERE DEW POINT POOLING OCCURRED AHEAD OF THE
FRONT AS WELL AS SOME SURFACE HEATING AS CLOUDS SCATTERED OUT.
THIS IS ALSO UNDER AN AREA OF STEEP MID LEVEL LAPSE RATES THAT
HAVE ALLOWED CONVECTION TO GROW IN DEPTH. SW END OF THIS LINE
HAVING TROUBLE STRENGTHENING/MAINTAINING ITSELF AS SUN LOWERS AND
EXPECT TS ACTIVITY TO PASS ACROSS E CENTRAL AND SE WI AND MISS NE
IL. IN BETWEEN THE GROWING COMPLEX TO THE SW AND THE NARROW LINE
TO THE N ONLY EXPECT SCATTERED VERY LIGHT SHOWERS ACROSS THE
TERMINALS.

INCREASING LOW LEVEL DEW POINTS AHEAD OF THE APPROACHING FRONT
RESULTING IN MVFR CEILINGS AND VISIBILITIES IN N CENTRAL IL AND
SPREADING INTO NE IL THUS HAVE BROUGHT CONDITIONS DOWN FOR A PERIOD
THIS EVENING UNTIL FRONT WEAKLY PASSES THROUGH...AROUND 03Z FOR
RFD AND 05Z-07Z DPA...ORD...MDW. BESIDES SOME ANVIL CIRRUS
SPREADING NORTHEASTWARD...SATELLITE SHOWS RAPID CLEARING FOLLOWING
FROPA. GIVEN DELAY IN STRONG ADVECTION OF DRIER AIR SOUTHEASTWARD
INTO THE LOCAL AREA HAVE VISIBILITY DROPPING BACK TO MVFR FOR A
FEW HOURS STARTING BEFORE SUNRISE.

TRS

&&

.MARINE...

245 PM CDT

A COLD FRONT WILL APPROACH LAKE MICHIGAN TONIGHT. THIS WILL GIVE A
WIND SHIFT FROM THE SOUTH TO NORTHWEST BY FRIDAY MORNING. BY
SATURDAY MORNING A HIGH WILL MOVE INTO THE REGION FROM IOWA TO
MICHIGAN. WE EXPECT THE WIND WILL BECOME LIGHT SATURDAY. HOWEVER
ON FRIDAY THERE WILL BE A WIND OF 15 TO 20 KNOTS. THIS MAY PRODUCE
SOME SIGNIFICANT WAVES OF 3 TO 5 FEET ON THE SOUTH HALF OF LAKE
MICHIGAN FRIDAY.

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KILX 290014
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
714 PM CDT THU AUG 28 2008

.DISCUSSION...
ISSUED 714 PM CDT THU AUG 28 2008

DID A QUICK UPDATE TO THE GRIDS FOR LIKELY STORMS THIS EVENING IN
THE SW THIRD OF THE CWA. ADDED MENTION OF SEVERE STORMS WITH HAIL
AND WINDS FOR THE SEVERE THUNDERSTORM WATCH AREA AS WELL. WATCH IS
IN EFFECT UNTIL 06Z. THE STRONGEST PORTION OF THE BOW ECHO APPEARS
LIKE IT MAY CLIP SCOTT COUNTY. FARTHER TO THE NORTH AND EAST...THE
SEVERE THREAT WILL BE OF A SCATTERED NATURE AND PRIMARILY FOR
LARGE HAIL. LESS ORGANIZED DOWNBURSTS WILL STILL BE POSSIBLE IN
THAT AREA AS WELL.

UPDATED ZONES AND GRIDS ARE ALREADY AVAILABLE.

SHIMON
&&

.AVIATION...
ISSUED 636 PM CDT THU AUG 28 2008...FOR THE 00Z TAFS

STORMS ARE DEVELOPING IN OUR W CWA...AHEAD OF THE MAIN MCS IN N
MO. THE STORM TRACKS APPEAR TO TAKE MOST OF THE ACTIVITY SOUTH OF
LINCOLN...WITH SPI IN THE PATH OF THE STRONGEST STORMS. HAVE HIT
SPI THE HARDEST WITH IFR VIS TO 1SM...+TSRA AND GUSTY WINDS BETWEEN
00Z AND 03Z. DEC MAY SEE SOME OF THAT...BUT AREAS N AND E OF SPI
WILL SEE MORE SCATTERED STORMS AND A BIT WEAKER. MAY BE SEEING A
SVR STORM WATCH SOON FOR OUR SW AREAS AS WELL.

DID NOT EXTEND THE VCTS IN THE TAFS MUCH BEYOND 06Z...BUT MAY NEED
TO ADJUST AS THE LINE PROGRESSES INTO OUR CWA.

FOG IS EXPECTED TO BECOME LOCALLY DENSE IN THE WAKE OF THESE
STORMS. CMI WILL HAVE A CHANCE FOR VLIFR VIS AGAIN...SINCE THE
LOWER DEWPOINT AIR IS LAGGING WELL BEHIND THIS LINE OF STORMS.
DEWPOINTS WILL LIKELY REMAIN AROUND 70 IN MUCH OF THE AREA THROUGH
MORNING. WILL KEEP AT LEAST IFR FOG IN A TEMPO FOR ALL SITES.

SHIMON
&&

.PREV DISCUSSION...
ISSUED 300 PM CDT THU AUG 28 2008

SHORT TERM...TONIGHT THROUGH SUNDAY...
MCS THAT MOVED ACROSS CENTRAL ILLINOIS EARLIER TODAY HAS LEFT A
MODIFIED AIRMASS THAT SHOULD PRECLUDE ANY MEANINGFUL CONVECTION INTO
THE EARLY EVENING HOURS. THE WESTERN EDGE OF THIS BUBBLE OF
RELATIVELY STABLE AIR IS RECOVERING OVER NORTHEASTERN MISSOURI...
AND THIS PROCESS SHOULD CONTINUE EASTWARD INTO WESTERN ILLINOIS
THROUGH 00Z UNTIL THE SUN BEGINS TO GO DOWN. UPSTREAM AIRMASS OVER
NORTHERN MISSOURI AND NORTHEAST KANSAS IS QUITE UNSTABLE NEAR THE
COLD FRONT THAT EXTENDS FROM CENTRAL IOWA TO JUST NORTHWEST OF
TOPEKA. HEALTHY ELEVATED CONVECTION IS INCREASING NORTH OF THE FRONT
OVER SOUTHEAST NEBRASKA...AND EXPECT FURTHER DEVELOPMENT OF A
SURFACE-BASED VARIETY ACROSS NORTHERN MISSOURI. SOME CHANCE THAT OUR
AIRMASS MAY RECOVER SUFFICIENTLY TO SUPPORT A HAIL/WIND THREAT IN
THE WEST AS THE DEVELOPING STORMS MOVE EASTWARD ALONG THE SOUTHERN
EDGE OF THE UPPER JET. WILL HOLD OFF ON LIKELY POPS DUE TO QUESTIONS
REGARDING AREAL COVERAGE...BUT WILL STILL HAVE HEALTHY CHANCE POPS
OVER THE WEST/SOUTHWEST.

THE COLD FRONT SHOULD PROGRESS TOWARD THE ILLINOIS RIVER VALLEY BY
MIDNIGHT WITH A REDUCTION IN PRECIPITATION IN ITS WAKE. WILL
THEREFORE TAKE POPS DOWN TO SLIGHT CHANCE AFTER 06Z IN THE
NORTHWEST. AS THE FRONT MAKES IT INTO THE SOUTHEAST BY 12Z FRI...IT
WILL BECOME INCREASINGLY SEPARATED FROM ITS ASSOCIATED UPPER TROUGH
THAT WILL BE MOVING INTO THE EASTERN GREAT LAKES. IT SHOULD
THEREFORE SLOW DOWN AND POSE AT LEAST A CHANCE OF ADDITIONAL
PRECIPITATION SOUTHEAST OF INTERSTATE 70 FOR THE MORNING AND EARLY
AFTERNOON HOURS. FORECAST SOUNDINGS OVER THAT AREA SHOW CAPE VALUES
OF 2000-2500 J/KG BY 18Z BEFORE THE DRIER AIR PUSHES COMPLETELY
THROUGH...SO WILL MAINTAIN CHANCE POPS DOWN THERE INTO EARLY
AFTERNOON.

REMAINDER OF SHORT TERM PERIOD FRIDAY NIGHT THROUGH SUNDAY SHOULD BE
MAINLY CLEAR AND DRY AS HIGH PRESSURE NOW OVER THE PLAINS COMES EAST
AND PARKS ACROSS THE MIDWEST.

LONG TERM...MONDAY THROUGH THURSDAY...
MONDAY AND TUESDAY WILL CONTINUE TO BE DRY WITH A WARMING TREND AS
HIGH PRESSURE REMAINS ANCHORED FROM THE GREAT LAKES SOUTHWESTWARD
INTO THE CENTRAL PLAINS. THE GFS AND ECMWF MODELS BOTH INDICATE A
CONUS UPPER PATTERN FEATURING A TROUGH-WEST RIDGE-EAST WHICH WILL
AID IN WARMING HIGHS INTO THE LOWER 90S...ESPECIALLY IN SOUTHEASTERN
ILLINOIS.

BY WEDNESDAY...THE WESTERN TROUGH WILL BEGIN TO MOVE NORTHEAST INTO
SOUTH-CENTRAL CANADA AND DRIVE THE NEXT COLD FRONT INTO THE MIDWEST.
BY THEN...THE REMAINS OF GUSTAV WILL ALSO BE MOVING NORTH TOWARD
ARKANSAS. LIKE YESTERDAY...THE ECMWF DEPICTION OF THE TRACK OF
GUSTAV FITS REASONABLY WELL THE THE LATEST NHC PROJECTED TRACK. IN
ANY EVENT...A COMPLICATED SITUATION WILL EVOLVE WITH A POSSIBLE
INTERACTION BETWEEN THE COLD FRONT AND THE DEEP TROPICAL MOISTURE
FROM THE REMAINS OF GUSTAV. PREDICTABILITY IS STILL RATHER POOR THIS
FAR IN ADVANCE...BUT WILL RAISE POPS INTO THE SLIGHT CHANCE TO
CHANCE CATEGORIES WEDNESDAY AND THURSDAY.

04

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 282350
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
650 PM CDT THU AUG 28 2008

.DISCUSSION...
650 PM CDT

GRIDS/DERIVED PRODUCTS BEING UPDATED AT THIS TIME TO REMOVE
THUNDER FROM FORECAST FOR THIS EVENING OVER ALL BUT FAR SOUTHERN
CWA. VISIBLE SATELLITE IMAGERY SHOWS STRATUS DECK MOVING ACROSS CWA
WITH NO INDICATION OF ANY APPRECIABLE VERTICAL DEVELOPMENT IN THE
DECK. IR IMAGERY INDICATES CLOUD TOP TEMPS ALL ABOVE FREEZING...SO
NO ICE CRYSTALS IN CLOUDINESS SHOULD RESULT IN WARM RAIN PROCESSES
AND GENERALLY SMALL DROPLET DIAMETER WITH ANY PRECIP THAT FALLS
FROM THIS DECK. GIVEN THIS AND PRONOUNCED CAP EVIDENT IN RECENT
ACARS SOUNDINGS HAVE JUST GONE WITH LIGHT RAIN/DRIZZLE THIS
EVENING OVER ALL BUT FAR SOUTHERN CWA WHERE SOME WEAK INSTABILITY
MAY BE PRESENT GIVEN CHARACTER OF CLOUDINESS ON VIS IMAGERY.

FARTHER NW...CLOSER TO THE FRONT...NARROW LINE OF
SHOWERS/THUNDERSTORMS HAVE DEVELOPED OVER CENTRAL WISCONSIN. WOULD
FULLY EXPECT THAT WITH TIME AND LOSS OF INSOLATION THAT THESE
STORMS WILL DISSIPATE BEFORE MAKING IT INTO ILLINOIS...BUT GIVEN
THAT FORECAST ALREADY HAD MENTION OF THUNDER DECIDED TO RETAIN
THAT FOR NOW AFTER MIDNIGHT BUT WILL RE-ACCESS LATER THIS
EVENING...AT WHICH TIME THE WI CONVECTION WILL HOPEFULLY HAVE
TIPPED ITS HAND GIVING SOME INDICATION OF ITS PLANS FOR THE
OVERNIGHT HOURS.

UPDATED PRODUCTS ALREADY SHIPPED.

IZZI

&&

.PREV DISCUSSION...
309 PM CDT

TOUGHEST PORTION OF THE FORECAST REMAINS WITH OUR CHANCES FOR
PRECIP THROUGH TONIGHT AND HOW POTENT THEY WILL BE. CLOUD COVER
FROM AN MCS THAT CAME THROUGH EARLIER TODAY HAS REALLY HELD BACK
TEMPERATURES FROM REBOUNDING THIS AFTERNOON. MAIN HOPE FOR ANY
CONVECTIVE INITIATION WILL BE OUT AHEAD OF THE COLD FRONT
CURRENTLY PROPAGATING THROUGH EASTERN IOWA...BUT AT THIS POINT IT
IS NOT LOOKING ALL THAT GREAT. A FEW SHOWERS HAVE ALREADY POPPED
UP ALONG THE MISSISSIPPI...BUT A RAPID THICKENING OF THE CLOUD
DECK OUT IN THAT REGION HAS ONCE AGAIN STUNTED THE GROWTH OF THE
CELLS. SO...AM NOT EXPECTING MUCH IN THE WAY OF WIDESPREAD
CONVECTION...LET ALONE SEVERE CONVECTION. CONDITIONS ARE A BIT
BETTER FURTHER TO THE WEST WHERE DEW POINTS ARE UP NEAR 70 AND
SKIES CLEARED OUT QUICKER THAN THEY HAVE AROUND HERE. HAVE DROPPED
POPS DOWN BELOW LIKELY CATEGORY AND HAVE ADDED SCATTERED WORDING
WITH JUST SOME ISOLATED THUNDERSTORMS. AFTER THE FRONT COMES
THROUGH TONIGHT...SKIES ARE EXPECTED TO CLEAR OUT AND IN COMES THE
DRY CONDITIONS THROUGH THE MIDDLE OF NEXT WEEK.

IN THE UPPER LEVELS OF THE ATMOSPHERE...AN AMPLIFYING RIDGE IS
EXPECTED TO LIFT NORTHWARD FROM THE GULF COAST ON UP INTO THE
GREAT LAKES BY EARLY NEXT WEEK. MOST OF THE MIDWEST WILL BE IN
SOUTHERLY FLOW FROM THE SFC ON UP INTO THE UPPER PORTIONS OF THE
ATMOSPHERE...WHICH WILL LEAD TO A SURGE OF WARMER AIR INTO THE
REGION. 850MB TEMPS ARE EXPECTED TO QUICKLY CLIMB INTO THE 17C TO
19C RANGE ON SUNDAY AS THE UPPER LEVEL RIDGE AXIS PROPAGATES INTO
THE CENTRAL LAKES. THIS SHOULD LEAD TO HIGH TEMPS REACHING THE MID
TO HIGH 80S FROM THE WEEKEND ON INTO THE MIDDLE OF NEXT WEEK. THIS
COULD BE ONE OF THE BETTER "HEAT WAVES" OF THE SUMMER AS THERE
WONT BE ANY STALLED OUT FRONTAL BOUNDARIES NEAR THE REGION THAT A
WAYWARD MCS CAN TRACK ALONG AND HOLD BACK TEMPERATURES.
INSTEAD...WE SHOULD BE IN THE CORE OF THE RIDGE AWAY FROM ANY
OTHER INFLUENCES OR CLOUD COVER THAT WOULD INHIBIT ANY LOWERING OF
TEMPERATURES. WILL REFRAIN FROM TOSSING IN ANY 90 DEGREE TEMPS UP
NEAR RFD YET...BUT AT THIS POINT WOULD NOT BE SURPRISED TO SEE
THEM GET THEIR FIRST 90 OF THE YEAR.

NEXT CHANCE AT ANY PRECIP WILL BE TOWARD THURSDAY AS A COLD FRONT
COMES THROUGH THE REGION IN ASSOCIATION WITH AN UPPER LEVEL
SHORTWAVE. THERE STILL ARE SOME TIMING DIFFERENCES BETWEEN THE
ECMWF AND GFS...BUT IT LOOKS LIKE THEIR TRENDING TOWARD THE ECMWF
SOLUTION OF BRINGING IT THROUGH LATER RATHER THAN EARLIER. THE
REMNANTS OF GUSTAV MAY ALSO PUMP SOME MOISTURE UP IN AHEAD OF THE
FRONT AND ADD MORE COVERAGE OF PRECIP. SO...ADDED SOME LOW CHANCE
POPS WEDNESDAY NIGHT INTO THURSDAY.

HALBACH

&&

.AVIATION...
1230 PM

THUNDERSTORMS ARE THE FORECAST PROBLEM THIS AFTERNOON AND EVENING.

THE COLD FRONT IS FORECAST TO MOVE THROUGH NORTH CENTRAL ILLINOIS
BETWEEN 23 UTC AND 02 UTC. SHOWERS AND THUNDERSTORMS ARE FORECAST TO
MOVE THROUGH ROCKFORD AT THAT TIME. THE FRONT IS EXPECTED TO MOVE
THROUGH NORTHEAST ILLINOIS AND NORTHWEST INDIANA BY 03 UTC. WE
EXPECT SHOWERS AND THUNDERSTORMS BETWEEN 00 UTC AND 03 UTC FOR THE
CHICAGO AREA AIRPORTS AND GARY. LINGERING SHOWERS ARE EXPECTED AFTER
THE FRONT PASSES AND WE WILL FORECAST MVFR CEILINGS. SOME GROUND FOG
MAY BE AROUND AFTER 06 UTC. A TEMPERATURE INVERSION IS FORECAST
BETWEEN 1000 TO 1200 FEET FRIDAY MORNING. THE WIND IS EXPECTED TO BE
FROM THE NORTH FRIDAY AND WE EXPECT A DECREASE IN MOISTURE IN THE
AIR. WE WILL FORECAST VFR CONDITIONS ON FRIDAY.

&&

.MARINE...

245 PM CDT

A COLD FRONT WILL APPROACH LAKE MICHIGAN TONIGHT. THIS WILL GIVE A
WIND SHIFT FROM THE SOUTH TO NORTHWEST BY FRIDAY MORNING. BY
SATURDAY MORNING A HIGH WILL MOVE INTO THE REGION FROM IOWA TO
MICHIGAN. WE EXPECT THE WIND WILL BECOME LIGHT SATURDAY. HOWEVER
ON FRIDAY THERE WILL BE A WIND OF 15 TO 20 KNOTS. THIS MAY PRODUCE
SOME SIGNIFICANT WAVES OF 3 TO 5 FEET ON THE SOUTH HALF OF LAKE
MICHIGAN FRIDAY.

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KILX 282335
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
635 PM CDT THU AUG 28 2008

.DISCUSSION...
ISSUED 300 PM CDT THU AUG 28 2008

SHORT TERM...TONIGHT THROUGH SUNDAY...
MCS THAT MOVED ACROSS CENTRAL ILLINOIS EARLIER TODAY HAS LEFT A
MODIFIED AIRMASS THAT SHOULD PRECLUDE ANY MEANINGFUL CONVECTION INTO
THE EARLY EVENING HOURS. THE WESTERN EDGE OF THIS BUBBLE OF
RELATIVELY STABLE AIR IS RECOVERING OVER NORTHEASTERN MISSOURI...
AND THIS PROCESS SHOULD CONTINUE EASTWARD INTO WESTERN ILLINOIS
THROUGH 00Z UNTIL THE SUN BEGINS TO GO DOWN. UPSTREAM AIRMASS OVER
NORTHERN MISSOURI AND NORTHEAST KANSAS IS QUITE UNSTABLE NEAR THE
COLD FRONT THAT EXTENDS FROM CENTRAL IOWA TO JUST NORTHWEST OF
TOPEKA. HEALTHY ELEVATED CONVECTION IS INCREASING NORTH OF THE FRONT
OVER SOUTHEAST NEBRASKA...AND EXPECT FURTHER DEVELOPMENT OF A
SURFACE-BASED VARIETY ACROSS NORTHERN MISSOURI. SOME CHANCE THAT OUR
AIRMASS MAY RECOVER SUFFICIENTLY TO SUPPORT A HAIL/WIND THREAT IN
THE WEST AS THE DEVELOPING STORMS MOVE EASTWARD ALONG THE SOUTHERN
EDGE OF THE UPPER JET. WILL HOLD OFF ON LIKELY POPS DUE TO QUESTIONS
REGARDING AREAL COVERAGE...BUT WILL STILL HAVE HEALTHY CHANCE POPS
OVER THE WEST/SOUTHWEST.

THE COLD FRONT SHOULD PROGRESS TOWARD THE ILLINOIS RIVER VALLEY BY
MIDNIGHT WITH A REDUCTION IN PRECIPITATION IN ITS WAKE. WILL
THEREFORE TAKE POPS DOWN TO SLIGHT CHANCE AFTER 06Z IN THE
NORTHWEST. AS THE FRONT MAKES IT INTO THE SOUTHEAST BY 12Z FRI...IT
WILL BECOME INCREASINGLY SEPARATED FROM ITS ASSOCIATED UPPER TROUGH
THAT WILL BE MOVING INTO THE EASTERN GREAT LAKES. IT SHOULD
THEREFORE SLOW DOWN AND POSE AT LEAST A CHANCE OF ADDITIONAL
PRECIPITATION SOUTHEAST OF INTERSTATE 70 FOR THE MORNING AND EARLY
AFTERNOON HOURS. FORECAST SOUNDINGS OVER THAT AREA SHOW CAPE VALUES
OF 2000-2500 J/KG BY 18Z BEFORE THE DRIER AIR PUSHES COMPLETELY
THROUGH...SO WILL MAINTAIN CHANCE POPS DOWN THERE INTO EARLY
AFTERNOON.

REMAINDER OF SHORT TERM PERIOD FRIDAY NIGHT THROUGH SUNDAY SHOULD BE
MAINLY CLEAR AND DRY AS HIGH PRESSURE NOW OVER THE PLAINS COMES EAST
AND PARKS ACROSS THE MIDWEST.

LONG TERM...MONDAY THROUGH THURSDAY...
MONDAY AND TUESDAY WILL CONTINUE TO BE DRY WITH A WARMING TREND AS
HIGH PRESSURE REMAINS ANCHORED FROM THE GREAT LAKES SOUTHWESTWARD
INTO THE CENTRAL PLAINS. THE GFS AND ECMWF MODELS BOTH INDICATE A
CONUS UPPER PATTERN FEATURING A TROUGH-WEST RIDGE-EAST WHICH WILL
AID IN WARMING HIGHS INTO THE LOWER 90S...ESPECIALLY IN SOUTHEASTERN
ILLINOIS.

BY WEDNESDAY...THE WESTERN TROUGH WILL BEGIN TO MOVE NORTHEAST INTO
SOUTH-CENTRAL CANADA AND DRIVE THE NEXT COLD FRONT INTO THE MIDWEST.
BY THEN...THE REMAINS OF GUSTAV WILL ALSO BE MOVING NORTH TOWARD
ARKANSAS. LIKE YESTERDAY...THE ECMWF DEPICTION OF THE TRACK OF
GUSTAV FITS REASONABLY WELL THE THE LATEST NHC PROJECTED TRACK. IN
ANY EVENT...A COMPLICATED SITUATION WILL EVOLVE WITH A POSSIBLE
INTERACTION BETWEEN THE COLD FRONT AND THE DEEP TROPICAL MOISTURE
FROM THE REMAINS OF GUSTAV. PREDICTABILITY IS STILL RATHER POOR THIS
FAR IN ADVANCE...BUT WILL RAISE POPS INTO THE SLIGHT CHANCE TO
CHANCE CATEGORIES WEDNESDAY AND THURSDAY.

04

&&

.AVIATION...
ISSUED 636 PM CDT THU AUG 28 2008...FOR THE 00Z TAFS

STORMS ARE DEVELOPING IN OUR W CWA...AHEAD OF THE MAIN MCS IN N
MO. THE STORM TRACKS APPEAR TO TAKE MOST OF THE ACTIVITY SOUTH OF
LINCOLN...WITH SPI IN THE PATH OF THE STRONGEST STORMS. HAVE HIT
SPI THE HARDEST WITH IFR VIS TO 1SM...+TSRA AND GUSTY WINDS BETWEEN
00Z AND 03Z. DEC MAY SEE SOME OF THAT...BUT AREAS N AND E OF SPI
WILL SEE MORE SCATTERED STORMS AND A BIT WEAKER. MAY BE SEEING A
SVR STORM WATCH SOON FOR OUR SW AREAS AS WELL.

DID NOT EXTEND THE VCTS IN THE TAFS MUCH BEYOND 06Z...BUT MAY NEED
TO ADJUST AS THE LINE PROGRESSES INTO OUR CWA.

FOG IS EXPECTED TO BECOME LOCALLY DENSE IN THE WAKE OF THESE
STORMS. CMI WILL HAVE A CHANCE FOR VLIFR VIS AGAIN...SINCE THE
LOWER DEWPOINT AIR IS LAGGING WELL BEHIND THIS LINE OF STORMS.
DEWPOINTS WILL LIKELY REMAIN AROUND 70 IN MUCH OF THE AREA THROUGH
MORNING. WILL KEEP AT LEAST IFR FOG IN A TEMPO FOR ALL SITES.

SHIMON
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 282009
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
309 PM CDT THU AUG 28 2008

.DISCUSSION...
309 PM CDT

TOUGHEST PORTION OF THE FORECAST REMAINS WITH OUR CHANCES FOR
PRECIP THROUGH TONIGHT AND HOW POTENT THEY WILL BE. CLOUD COVER
FROM AN MCS THAT CAME THROUGH EARLIER TODAY HAS REALLY HELD BACK
TEMPERATURES FROM REBOUNDING THIS AFTERNOON. MAIN HOPE FOR ANY
CONVECTIVE INITIATION WILL BE OUT AHEAD OF THE COLD FRONT
CURRENTLY PROPAGATING THROUGH EASTERN IOWA...BUT AT THIS POINT IT
IS NOT LOOKING ALL THAT GREAT. A FEW SHOWERS HAVE ALREADY POPPED
UP ALONG THE MISSISSIPPI...BUT A RAPID THICKENING OF THE CLOUD
DECK OUT IN THAT REGION HAS ONCE AGAIN STUNTED THE GROWTH OF THE
CELLS. SO...AM NOT EXPECTING MUCH IN THE WAY OF WIDESPREAD
CONVECTION...LET ALONE SEVERE CONVECTION. CONDITIONS ARE A BIT
BETTER FURTHER TO THE WEST WHERE DEW POINTS ARE UP NEAR 70 AND
SKIES CLEARED OUT QUICKER THAN THEY HAVE AROUND HERE. HAVE DROPPED
POPS DOWN BELOW LIKELY CATEGORY AND HAVE ADDED SCATTERED WORDING
WITH JUST SOME ISOLATED THUNDERSTORMS. AFTER THE FRONT COMES
THROUGH TONIGHT...SKIES ARE EXPECTED TO CLEAR OUT AND IN COMES THE
DRY CONDITIONS THROUGH THE MIDDLE OF NEXT WEEK.

IN THE UPPER LEVELS OF THE ATMOSPHERE...AN AMPLIFYING RIDGE IS
EXPECTED TO LIFT NORTHWARD FROM THE GULF COAST ON UP INTO THE
GREAT LAKES BY EARLY NEXT WEEK. MOST OF THE MIDWEST WILL BE IN
SOUTHERLY FLOW FROM THE SFC ON UP INTO THE UPPER PORTIONS OF THE
ATMOSPHERE...WHICH WILL LEAD TO A SURGE OF WARMER AIR INTO THE
REGION. 850MB TEMPS ARE EXPECTED TO QUICKLY CLIMB INTO THE 17C TO
19C RANGE ON SUNDAY AS THE UPPER LEVEL RIDGE AXIS PROPAGATES INTO
THE CENTRAL LAKES. THIS SHOULD LEAD TO HIGH TEMPS REACHING THE MID
TO HIGH 80S FROM THE WEEKEND ON INTO THE MIDDLE OF NEXT WEEK. THIS
COULD BE ONE OF THE BETTER "HEAT WAVES" OF THE SUMMER AS THERE
WONT BE ANY STALLED OUT FRONTAL BOUNDARIES NEAR THE REGION THAT A
WAYWARD MCS CAN TRACK ALONG AND HOLD BACK TEMPERATURES.
INSTEAD...WE SHOULD BE IN THE CORE OF THE RIDGE AWAY FROM ANY
OTHER INFLUENCES OR CLOUD COVER THAT WOULD INHIBIT ANY LOWERING OF
TEMPERATURES. WILL REFRAIN FROM TOSSING IN ANY 90 DEGREE TEMPS UP
NEAR RFD YET...BUT AT THIS POINT WOULD NOT BE SURPRISED TO SEE
THEM GET THEIR FIRST 90 OF THE YEAR.

NEXT CHANCE AT ANY PRECIP WILL BE TOWARD THURSDAY AS A COLD FRONT
COMES THROUGH THE REGION IN ASSOCIATION WITH AN UPPER LEVEL
SHORTWAVE. THERE STILL ARE SOME TIMING DIFFERENCES BETWEEN THE
ECMWF AND GFS...BUT IT LOOKS LIKE THEIR TRENDING TOWARD THE ECMWF
SOLUTION OF BRINGING IT THROUGH LATER RATHER THAN EARLIER. THE
REMNANTS OF GUSTAV MAY ALSO PUMP SOME MOISTURE UP IN AHEAD OF THE
FRONT AND ADD MORE COVERAGE OF PRECIP. SO...ADDED SOME LOW CHANCE
POPS WEDNESDAY NIGHT INTO THURSDAY.

HALBACH

&&

.AVIATION...
1230 PM

THUNDERSTORMS ARE THE FORECAST PROBLEM THIS AFTERNOON AND EVENING.

THE COLD FRONT IS FORECAST TO MOVE THROUGH NORTH CENTRAL ILLINOIS
BETWEEN 23 UTC AND 02 UTC. SHOWERS AND THUNDERSTORMS ARE FORECAST TO
MOVE THROUGH ROCKFORD AT THAT TIME. THE FRONT IS EXPECTED TO MOVE
THROUGH NORTHEAST ILLINOIS AND NORTHWEST INDIANA BY 03 UTC. WE
EXPECT SHOWERS AND THUNDERSTORMS BETWEEN 00 UTC AND 03 UTC FOR THE
CHICAGO AREA AIRPORTS AND GARY. LINGERING SHOWERS ARE EXPECTED AFTER
THE FRONT PASSES AND WE WILL FORECAST MVFR CEILINGS. SOME GROUND FOG
MAY BE AROUND AFTER 06 UTC. A TEMPERATURE INVERSION IS FORECAST
BETWEEN 1000 TO 1200 FEET FRIDAY MORNING. THE WIND IS EXPECTED TO BE
FROM THE NORTH FRIDAY AND WE EXPECT A DECREASE IN MOISTURE IN THE
AIR. WE WILL FORECAST VFR CONDITIONS ON FRIDAY.

&&

.MARINE...

245 PM CDT

A COLD FRONT WILL APPROACH LAKE MICHIGAN TONIGHT. THIS WILL GIVE A
WIND SHIFT FROM THE SOUTH TO NORTHWEST BY FRIDAY MORNING. BY
SATURDAY MORNING A HIGH WILL MOVE INTO THE REGION FROM IOWA TO
MICHIGAN. WE EXPECT THE WIND WILL BECOME LIGHT SATURDAY. HOWEVER
ON FRIDAY THERE WILL BE A WIND OF 15 TO 20 KNOTS. THIS MAY PRODUCE
SOME SIGNIFICANT WAVES OF 3 TO 5 FEET ON THE SOUTH HALF OF LAKE
MICHIGAN FRIDAY.

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KILX 282001
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
300 PM CDT THU AUG 28 2008

.DISCUSSION...
ISSUED 300 PM CDT THU AUG 28 2008

SHORT TERM...TONIGHT THROUGH SUNDAY...
MCS THAT MOVED ACROSS CENTRAL ILLINOIS EARLIER TODAY HAS LEFT A
MODIFIED AIRMASS THAT SHOULD PRECLUDE ANY MEANINGFUL CONVECTION INTO
THE EARLY EVENING HOURS. THE WESTERN EDGE OF THIS BUBBLE OF
RELATIVELY STABLE AIR IS RECOVERING OVER NORTHEASTERN MISSOURI...
AND THIS PROCESS SHOULD CONTINUE EASTWARD INTO WESTERN ILLINOIS
THROUGH 00Z UNTIL THE SUN BEGINS TO GO DOWN. UPSTREAM AIRMASS OVER
NORTHERN MISSOURI AND NORTHEAST KANSAS IS QUITE UNSTABLE NEAR THE
COLD FRONT THAT EXTENDS FROM CENTRAL IOWA TO JUST NORTHWEST OF
TOPEKA. HEALTHY ELEVATED CONVECTION IS INCREASING NORTH OF THE FRONT
OVER SOUTHEAST NEBRASKA...AND EXPECT FURTHER DEVELOPMENT OF A
SURFACE-BASED VARIETY ACROSS NORTHERN MISSOURI. SOME CHANCE THAT OUR
AIRMASS MAY RECOVER SUFFICIENTLY TO SUPPORT A HAIL/WIND THREAT IN
THE WEST AS THE DEVELOPING STORMS MOVE EASTWARD ALONG THE SOUTHERN
EDGE OF THE UPPER JET. WILL HOLD OFF ON LIKELY POPS DUE TO QUESTIONS
REGARDING AREAL COVERAGE...BUT WILL STILL HAVE HEALTHY CHANCE POPS
OVER THE WEST/SOUTHWEST.

THE COLD FRONT SHOULD PROGRESS TOWARD THE ILLINOIS RIVER VALLEY BY
MIDNIGHT WITH A REDUCTION IN PRECIPITATION IN ITS WAKE. WILL
THEREFORE TAKE POPS DOWN TO SLIGHT CHANCE AFTER 06Z IN THE
NORTHWEST. AS THE FRONT MAKES IT INTO THE SOUTHEAST BY 12Z FRI...IT
WILL BECOME INCREASINGLY SEPARATED FROM ITS ASSOCIATED UPPER TROUGH
THAT WILL BE MOVING INTO THE EASTERN GREAT LAKES. IT SHOULD
THEREFORE SLOW DOWN AND POSE AT LEAST A CHANCE OF ADDITIONAL
PRECIPITATION SOUTHEAST OF INTERSTATE 70 FOR THE MORNING AND EARLY
AFTERNOON HOURS. FORECAST SOUNDINGS OVER THAT AREA SHOW CAPE VALUES
OF 2000-2500 J/KG BY 18Z BEFORE THE DRIER AIR PUSHES COMPLETELY
THROUGH...SO WILL MAINTAIN CHANCE POPS DOWN THERE INTO EARLY
AFTERNOON.

REMAINDER OF SHORT TERM PERIOD FRIDAY NIGHT THROUGH SUNDAY SHOULD BE
MAINLY CLEAR AND DRY AS HIGH PRESSURE NOW OVER THE PLAINS COMES EAST
AND PARKS ACROSS THE MIDWEST.

LONG TERM...MONDAY THROUGH THURSDAY...
MONDAY AND TUESDAY WILL CONTINUE TO BE DRY WITH A WARMING TREND AS
HIGH PRESSURE REMAINS ANCHORED FROM THE GREAT LAKES SOUTHWESTWARD
INTO THE CENTRAL PLAINS. THE GFS AND ECMWF MODELS BOTH INDICATE A
CONUS UPPER PATTERN FEATURING A TROUGH-WEST RIDGE-EAST WHICH WILL
AID IN WARMING HIGHS INTO THE LOWER 90S...ESPECIALLY IN SOUTHEASTERN
ILLINOIS.

BY WEDNESDAY...THE WESTERN TROUGH WILL BEGIN TO MOVE NORTHEAST INTO
SOUTH-CENTRAL CANADA AND DRIVE THE NEXT COLD FRONT INTO THE MIDWEST.
BY THEN...THE REMAINS OF GUSTAV WILL ALSO BE MOVING NORTH TOWARD
ARKANSAS. LIKE YESTERDAY...THE ECMWF DEPICTION OF THE TRACK OF
GUSTAV FITS REASONABLY WELL THE THE LATEST NHC PROJECTED TRACK. IN
ANY EVENT...A COMPLICATED SITUATION WILL EVOLVE WITH A POSSIBLE
INTERACTION BETWEEN THE COLD FRONT AND THE DEEP TROPICAL MOISTURE
FROM THE REMAINS OF GUSTAV. PREDICTABILITY IS STILL RATHER POOR THIS
FAR IN ADVANCE...BUT WILL RAISE POPS INTO THE SLIGHT CHANCE TO
CHANCE CATEGORIES WEDNESDAY AND THURSDAY.

04
&&

.AVIATION...
ISSUED 1244 PM CDT THU AUG 28 2008

REMNANTS OF MORNING MCS CONTINUE TO TRACK ACROSS CENTRAL ILLINOIS
EARLY THIS AFTERNOON...WITH BAND OF LIGHT RAIN SHOWERS CURRENTLY
EXTENDING FROM KCMI...TO KDEC...TO JUST SOUTH OF KSPI. ONCE THIS
PRECIP CLEARS THE TAF SITES IN THE NEXT HOUR OR SO...CONDITIONS WILL
REMAIN DRY UNTIL LATER THIS AFTERNOON INTO THE EVENING WHEN A COLD
FRONT BEGINS TO APPROACH FROM THE WEST. SCATTERED CONVECTION IS
EXPECTED TO DEVELOP IN ADVANCE OF THE FRONT ACROSS IA THIS AFTN...
THEN PUSH INTO CENTRAL ILLINOIS TOWARD 00Z. WITH STABLE AIRMASS IN
PLACE ACROSS THE AREA...COVERAGE OF CONVECTION REMAINS A BIG
QUESTION. WILL THEREFORE ONLY MENTION VCTS IN THE TAFS UNTIL EXACT
CONVECTIVE TRENDS BECOME CLEARER. WINDS ARE EXPECTED TO BE FROM THE
SOUTH EARLY ON...BUT WILL SHIFT TO THE W/NW DURING THE 03Z TO 06Z
TIME FRAME. THANKS TO A DELAY IN THE ARRIVAL OF DRIER AIR...AREAS OF
FOG WILL LIKELY DEVELOP LATE TONIGHT AS SKIES CLEAR. WILL INCLUDE
TEMPO GROUPS FOR VISBYS DOWN TO AROUND 2SM AT ALL SITES. AFTER
THAT...LIGHT N/NE WINDS AND CLEAR SKIES WILL PREVAIL FRIDAY MORNING.

BARNES
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 281948
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
216 PM CDT THU AUG 28 2008

.DISCUSSION...
1001 AM CDT

STRONG 850MB WARM AIR ADVECTION NOTED ON 12Z PROFILER DATA WILL
SLIDE EASTWARD THIS MORNING ACROSS THE REGION. MODERATE RAIN
SHIELD EXTENDING NORTHEASTWARD ALONG THIS WAA WILL LIKELY CONTINUE
EASTWARD AS THE 850MB WINDS GO MORE WEST TO EAST INTO THE EARLY
AFTERNOON HOURS. SOME QUESTIONS REMAIN FOR THIS AFTERNOONS
CONVECTIVE POTENTIAL BEING MET DUE TO THE CURRENT SLUG OF RAIN
ACROSS NORTHEAST ILLINOIS. CURRENTLY STILL THINK THAT THERE SHOULD
BE ENOUGH MOISTURE...INSTABILITY AND LIFT FROM THE FRONT AND UPPER
LEVEL DYNAMICS THAT SHOWERS AND THUNDERSTORMS WILL REDEVELOP ALONG
AND AHEAD OF THE FRONT. WHETHER ANY CAN BECOME SEVERE REMAINS TO
BE SEEN AS THE 0-6KM WIND SHEAR WILL BE ON THE INCREASE AS A 500MB
JET STREAK ENTERS THE REGION. WITH ACARS SOUNDINGS OUT OF RFD AND
ORD SHOWING THE FREEZING LEVEL UP AROUND 14KFT...IT WILL TAKE SOME
VIGOROUS UPDRAFTS TO PRODUCE ANY SEVERE HAIL OR WINDS.

HALBACH

&&

.PREV DISCUSSION...

340 AM CDT

MAIN FORECAST CONCERN TODAY THROUGH THIS EVENING IS POTENTIAL FOR
SHOWERS AND THUNDERSTORMS AND SEVERE WEATHER.

A STRONG UPPER LEVEL STREAK OF 120-130 KNOTS SAMPLED IN LAST
EVENINGS RAOBS ACROSS MONTANA WILL CONTINUE TO PROGRESS THROUGH THE
BASE OF THE UPPER TROUGH THAT WILL AFFECT THE GREAT LAKES REGION
TODAY AND TONIGHT. SURFACE PRESSURE FALLS HAVE BEEN STRENGTHENING
OVERNIGHT ACROSS THE UPPER MS RIVER VALLEY WITH INCREASING LARGE
SCALE ASCENT AND BROAD LOW LEVEL ISENTROPIC. A FEW SHOWERS HAVE BEEN
TRYING TO DEVELOP THIS MORNING CLOSER TO THE MISSISSIPPI RIVER BUT
INSTABILITY IN THIS REGION OVERNIGHT HAS BEEN HIGHLY ELEVATED IN
NATURE. MORE IMPRESSIVE LOW LEVEL MOISTURE PROFILES REMAIN OFF TO
THE WEST THIS MORNING CLOSER TO THE LOW LEVEL FRONT SITUATED FROM
WESTERN/CENTRAL IOWA INTO NORTHWEST WISCONSIN. MORE WIDESPREAD
SHOWERS AND THUNDERSTORMS HAVE BEEN AFFECTING MUCH OF IOWA
OVERNIGHT...BUT AS LOW LEVEL JET VEERS MORE WESTERLY THIS
MORNING...AND AS ACTIVITY BEGINS TO MIGRATE AWAY FROM MAX
INSTABILITY AXIS SHOULD GRADUALLY SEE A DOWNWARD TREND IN INTENSITY
OF THESE SHOWERS AND THUNDERSTORMS. NONETHELESS...WILL LIKELY HAVE
SHOWERS AND SOME EMBEDDED THUNDER SURVIVE INTO NORTH CENTRAL
ILLINOIS EARLY THIS MORNING HAVE NUDGED UP POPS INTO LIKELY CATEGORY
FOR THIS MORNING. THUNDERSTORMS ARE EXPECTED TO REDEVELOP THIS
AFTERNOON AS LOW LEVEL THETA-E RIDGE IN ADVANCE OF THE FRONT
OVERSPREADS NORTH CENTRAL ILLINOIS WITH FORECAST SOUNDINGS SUGGEST
MLCAPES ON THE ORDER OF 1500-2000 J/KG AND DEEP LAYER SHEAR
MAGNITUDES UP AROUND 35-40 KNOTS ACROSS FAR NORTHERN ILLINOIS ON
SOUTHERN PERIPHERY OF AFOREMENTIONED UPPER JET STREAK ACROSS THE
UPPER MS RIVER VALLEY. BEST INSTABILITY IS EXPECTED TO SETUP THIS
AFTERNOON ACROSS NORTH CENTRAL ILLINOIS IN CLOSER PROXIMITY TO LOW
LEVEL THETA-E RIDGE...WITH INSTABILITY REMAINING MORE HIGHLY
ELEVATED AND LESSER IN MAGNITUDE ACROSS FAR NORTHEAST
ILLINOIS/NORTHWEST INDIANA SO WILL MAINTAIN ONLY CHANCE THUNDER
MENTION ACROSS NORTHEAST ILLINOIS TAPERING TO SLIGHT CHANCE ACROSS
MOST OF NWRN INDIANA COUNTIES. WITH MODERATE INSTABILITY AND
INCREASING DEEP LAYER SHEAR THIS AFTERNOON...A LOW END SEVERE THREAT
FOR HAIL/WINDS DOES APPEAR TO EXIST THIS AFTERNOON INTO EARLY THIS
EVENING ACROSS MUCH OF NORTH CENTRAL ILLINOIS PORTION OF THE CWA.
COMPLICATING FACTORS REGARDING THIS RISK WILL BE AMOUNT OF SURFACE
WARMING THAT CAN OCCUR FROM LEFTOVER DEBRIS FROM IOWA OVERNIGHT
CONVECTION. DESPITE POTENTIAL FOR CLOUDS LINGERING...WOULD SUSPECT
REACHING CONVEC TEMPS IN LOW TO MID 80S THIS AFTERNOON ACROSS NORTH
CENTRAL ILLINOIS WILL NOT BE A PROBLEM GIVEN INCREASING LOW LEVEL
MOISTURE.

BEST CHANCE OF THUNDER SHOULD BE LATE THIS AFTERNOON INTO THIS
EVENING WHEN LOW LEVEL CONVERGENCE MAXIMIZES WITH THE APPROACH OF
THE FRONT AND AS MAIN UPPER VORT MAX CURRENTLY MOVING THROUGH
CENTRAL SOUTH DAKOTA PROGRESSES THROUGH THE WESTERN GREAT LAKES.
BEST FORCING SHOULD REMAIN JUST NORTH OF THE AREA BUT SEE NO REASON
TO LOWER THE LIKELY POPS FOR THIS EVENING WITH LOW LEVEL CONVG ALONG
THE FRONT LIKELY SUFFICIENT TO MAINTAIN HIGH COVERAGE TO
SHOWERS/TSTORMS THIS EVENING. FRONT SHOULD BE EXITING SOUTHEAST
PORTIONS OF THE FORECAST AREA SHORTLY AFTER MIDNIGHT QUICKLY
ENDING PRECIP CHANCES. TEMPS TONIGHT SHOULD COOL BACK INTO THE MID
50S ACROSS FAR NWRN PORTIONS OF THE FORECAST AREA BEHIND THE FRONT
WITH CLEARING SKIES.

A DRY PLEASANT WEEKEND IS UPCOMING WITH BROAD SFC HIGH SETTLING OVER
THE GREAT LAKES. MODELS HAVE TRENDED OVER PAST FEW RUNS TO BE A BIT
QUICKER SHIFTING THE HIGH EASTWARD WITH A MORE RAPID WARMING TREND
SO DID NUDGE UP HIGHS A SHADE FOR THE WEEKEND. REST OF FORECAST LEFT
AS IS WITH WARM SUMMER-LIKE TEMPS EARLY NEXT WEEK AS AMPLIFIED
WESTERN CONUS TROUGH RESULTS IN RISING HEIGHTS ACROSS CENTRAL CONUS.

MARSILI

&&

.AVIATION...
1230 PM

THUNDERSTORMS ARE THE FORECAST PROBLEM THIS AFTERNOON AND EVENING.

THE COLD FRONT IS FORECAST TO MOVE THROUGH NORTH CENTRAL ILLINOIS
BETWEEN 23 UTC AND 02 UTC. SHOWERS AND THUNDERSTORMS ARE FORECAST TO
MOVE THROUGH ROCKFORD AT THAT TIME. THE FRONT IS EXPECTED TO MOVE
THROUGH NORTHEAST ILLINOIS AND NORTHWEST INDIANA BY 03 UTC. WE
EXPECT SHOWERS AND THUNDERSTORMS BETWEEN 00 UTC AND 03 UTC FOR THE
CHICAGO AREA AIRPORTS AND GARY. LINGERING SHOWERS ARE EXPECTED AFTER
THE FRONT PASSES AND WE WILL FORECAST MVFR CEILINGS. SOME GROUND FOG
MAY BE AROUND AFTER 06 UTC. A TEMPERATURE INVERSION IS FORECAST
BETWEEN 1000 TO 1200 FEET FRIDAY MORNING. THE WIND IS EXPECTED TO BE
FROM THE NORTH FRIDAY AND WE EXPECT A DECREASE IN MOISTURE IN THE
AIR. WE WILL FORECAST VFR CONDITIONS ON FRIDAY.

&&

.MARINE...

245 PM CDT

A COLD FRONT WILL APPROACH LAKE MICHIGAN TONIGHT. THIS WILL GIVE A
WIND SHIFT FROM THE SOUTH TO NORTHWEST BY FRIDAY MORNING. BY
SATURDAY MORNING A HIGH WILL MOVE INTO THE REGION FROM IOWA TO
MICHIGAN. WE EXPECT THE WIND WILL BECOME LIGHT SATURDAY. HOWEVER
ON FRIDAY THERE WILL BE A WIND OF 15 TO 20 KNOTS. THIS MAY PRODUCE
SOME SIGNIFICANT WAVES OF 3 TO 5 FEET ON THE SOUTH HALF OF LAKE
MICHIGAN FRIDAY.

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KLOT 281805
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1229 PM CDT THU AUG 28 2008

.DISCUSSION...
1001 AM CDT

STRONG 850MB WARM AIR ADVECTION NOTED ON 12Z PROFILER DATA WILL
SLIDE EASTWARD THIS MORNING ACROSS THE REGION. MODERATE RAIN
SHIELD EXTENDING NORTHEASTWARD ALONG THIS WAA WILL LIKELY CONTINUE
EASTWARD AS THE 850MB WINDS GO MORE WEST TO EAST INTO THE EARLY
AFTERNOON HOURS. SOME QUESTIONS REMAIN FOR THIS AFTERNOONS
CONVECTIVE POTENTIAL BEING MET DUE TO THE CURRENT SLUG OF RAIN
ACROSS NORTHEAST ILLINOIS. CURRENTLY STILL THINK THAT THERE SHOULD
BE ENOUGH MOISTURE...INSTABILITY AND LIFT FROM THE FRONT AND UPPER
LEVEL DYNAMICS THAT SHOWERS AND THUNDERSTORMS WILL REDEVELOP ALONG
AND AHEAD OF THE FRONT. WHETHER ANY CAN BECOME SEVERE REMAINS TO
BE SEEN AS THE 0-6KM WIND SHEAR WILL BE ON THE INCREASE AS A 500MB
JET STREAK ENTERS THE REGION. WITH ACARS SOUNDINGS OUT OF RFD AND
ORD SHOWING THE FREEZING LEVEL UP AROUND 14KFT...IT WILL TAKE SOME
VIGOROUS UPDRAFTS TO PRODUCE ANY SEVERE HAIL OR WINDS.

HALBACH

&&

.PREV DISCUSSION...

340 AM CDT

MAIN FORECAST CONCERN TODAY THROUGH THIS EVENING IS POTENTIAL FOR
SHOWERS AND THUNDERSTORMS AND SEVERE WEATHER.

A STRONG UPPER LEVEL STREAK OF 120-130 KNOTS SAMPLED IN LAST
EVENINGS RAOBS ACROSS MONTANA WILL CONTINUE TO PROGRESS THROUGH THE
BASE OF THE UPPER TROUGH THAT WILL AFFECT THE GREAT LAKES REGION
TODAY AND TONIGHT. SURFACE PRESSURE FALLS HAVE BEEN STRENGTHENING
OVERNIGHT ACROSS THE UPPER MS RIVER VALLEY WITH INCREASING LARGE
SCALE ASCENT AND BROAD LOW LEVEL ISENTROPIC. A FEW SHOWERS HAVE BEEN
TRYING TO DEVELOP THIS MORNING CLOSER TO THE MISSISSIPPI RIVER BUT
INSTABILITY IN THIS REGION OVERNIGHT HAS BEEN HIGHLY ELEVATED IN
NATURE. MORE IMPRESSIVE LOW LEVEL MOISTURE PROFILES REMAIN OFF TO
THE WEST THIS MORNING CLOSER TO THE LOW LEVEL FRONT SITUATED FROM
WESTERN/CENTRAL IOWA INTO NORTHWEST WISCONSIN. MORE WIDESPREAD
SHOWERS AND THUNDERSTORMS HAVE BEEN AFFECTING MUCH OF IOWA
OVERNIGHT...BUT AS LOW LEVEL JET VEERS MORE WESTERLY THIS
MORNING...AND AS ACTIVITY BEGINS TO MIGRATE AWAY FROM MAX
INSTABILITY AXIS SHOULD GRADUALLY SEE A DOWNWARD TREND IN INTENSITY
OF THESE SHOWERS AND THUNDERSTORMS. NONETHELESS...WILL LIKELY HAVE
SHOWERS AND SOME EMBEDDED THUNDER SURVIVE INTO NORTH CENTRAL
ILLINOIS EARLY THIS MORNING HAVE NUDGED UP POPS INTO LIKELY CATEGORY
FOR THIS MORNING. THUNDERSTORMS ARE EXPECTED TO REDEVELOP THIS
AFTERNOON AS LOW LEVEL THETA-E RIDGE IN ADVANCE OF THE FRONT
OVERSPREADS NORTH CENTRAL ILLINOIS WITH FORECAST SOUNDINGS SUGGEST
MLCAPES ON THE ORDER OF 1500-2000 J/KG AND DEEP LAYER SHEAR
MAGNITUDES UP AROUND 35-40 KNOTS ACROSS FAR NORTHERN ILLINOIS ON
SOUTHERN PERIPHERY OF AFOREMENTIONED UPPER JET STREAK ACROSS THE
UPPER MS RIVER VALLEY. BEST INSTABILITY IS EXPECTED TO SETUP THIS
AFTERNOON ACROSS NORTH CENTRAL ILLINOIS IN CLOSER PROXIMITY TO LOW
LEVEL THETA-E RIDGE...WITH INSTABILITY REMAINING MORE HIGHLY
ELEVATED AND LESSER IN MAGNITUDE ACROSS FAR NORTHEAST
ILLINOIS/NORTHWEST INDIANA SO WILL MAINTAIN ONLY CHANCE THUNDER
MENTION ACROSS NORTHEAST ILLINOIS TAPERING TO SLIGHT CHANCE ACROSS
MOST OF NWRN INDIANA COUNTIES. WITH MODERATE INSTABILITY AND
INCREASING DEEP LAYER SHEAR THIS AFTERNOON...A LOW END SEVERE THREAT
FOR HAIL/WINDS DOES APPEAR TO EXIST THIS AFTERNOON INTO EARLY THIS
EVENING ACROSS MUCH OF NORTH CENTRAL ILLINOIS PORTION OF THE CWA.
COMPLICATING FACTORS REGARDING THIS RISK WILL BE AMOUNT OF SURFACE
WARMING THAT CAN OCCUR FROM LEFTOVER DEBRIS FROM IOWA OVERNIGHT
CONVECTION. DESPITE POTENTIAL FOR CLOUDS LINGERING...WOULD SUSPECT
REACHING CONVEC TEMPS IN LOW TO MID 80S THIS AFTERNOON ACROSS NORTH
CENTRAL ILLINOIS WILL NOT BE A PROBLEM GIVEN INCREASING LOW LEVEL
MOISTURE.

BEST CHANCE OF THUNDER SHOULD BE LATE THIS AFTERNOON INTO THIS
EVENING WHEN LOW LEVEL CONVERGENCE MAXIMIZES WITH THE APPROACH OF
THE FRONT AND AS MAIN UPPER VORT MAX CURRENTLY MOVING THROUGH
CENTRAL SOUTH DAKOTA PROGRESSES THROUGH THE WESTERN GREAT LAKES.
BEST FORCING SHOULD REMAIN JUST NORTH OF THE AREA BUT SEE NO REASON
TO LOWER THE LIKELY POPS FOR THIS EVENING WITH LOW LEVEL CONVG ALONG
THE FRONT LIKELY SUFFICIENT TO MAINTAIN HIGH COVERAGE TO
SHOWERS/TSTORMS THIS EVENING. FRONT SHOULD BE EXITING SOUTHEAST
PORTIONS OF THE FORECAST AREA SHORTLY AFTER MIDNIGHT QUICKLY
ENDING PRECIP CHANCES. TEMPS TONIGHT SHOULD COOL BACK INTO THE MID
50S ACROSS FAR NWRN PORTIONS OF THE FORECAST AREA BEHIND THE FRONT
WITH CLEARING SKIES.

A DRY PLEASANT WEEKEND IS UPCOMING WITH BROAD SFC HIGH SETTLING OVER
THE GREAT LAKES. MODELS HAVE TRENDED OVER PAST FEW RUNS TO BE A BIT
QUICKER SHIFTING THE HIGH EASTWARD WITH A MORE RAPID WARMING TREND
SO DID NUDGE UP HIGHS A SHADE FOR THE WEEKEND. REST OF FORECAST LEFT
AS IS WITH WARM SUMMER-LIKE TEMPS EARLY NEXT WEEK AS AMPLIFIED
WESTERN CONUS TROUGH RESULTS IN RISING HEIGHTS ACROSS CENTRAL CONUS.

MARSILI

&&

.AVIATION...
1230 PM

THUNDERSTORMS ARE THE FORECAST PROBLEM THIS AFTERNOON AND EVENING.

THE COLD FRONT IS FORECAST TO MOVE THROUGH NORTH CENTRAL ILLINOIS
BETWEEN 23 UTC AND 02 UTC. SHOWERS AND THUNDERSTORMS ARE FORECAST TO
MOVE THROUGH ROCKFORD AT THAT TIME. THE FRONT IS EXPECTED TO MOVE
THROUGH NORTHEAST ILLINOIS AND NORTHWEST INDIANA BY 03 UTC. WE
EXPECT SHOWERS AND THUNDERSTORMS BETWEEN 00 UTC AND 03 UTC FOR THE
CHICAGO AREA AIRPORTS AND GARY. LINGERING SHOWERS ARE EXPECTED AFTER
THE FRONT PASSES AND WE WILL FORECAST MVFR CEILINGS. SOME GROUND FOG
MAY BE AROUND AFTER 06 UTC. A TEMPERATURE INVERSION IS FORECAST
BETWEEN 1000 TO 1200 FEET FRIDAY MORNING. THE WIND IS EXPECTED TO BE
FROM THE NORTH FRIDAY AND WE EXPECT A DECREASE IN MOISTURE IN THE
AIR. WE WILL FORECAST VFR CONDITIONS ON FRIDAY.

&&

.MARINE...

302 AM CDT

A COLD FRONT TRAILING FROM WEST OF HUDSON BAY INTO THE CENTRAL
PLAINS WILL BE THE FOCUS FOR SHORT TERM WEATHER CHANGES ACROSS
LAKE MICHIGAN THROUGH TONIGHT. A WEAK AREA OF LOW PRESSURE NEAR
OMAHA EARLY THIS MORNING WILL LIFT NORTHEAST ALONG THE FRONT AND
WILL MOVE ACROSS WISCONSIN AND LAKE MICHIGAN THROUGH THIS EVENING.
MODEST TIGHTENING OF THE PRESSURE GRADIENT AHEAD OF THIS FEATURE
WILL RESULT IN SOUTHERLY WINDS INCREASING THIS MORNING ACROSS THE
LAKE. WITH THE PASSAGE OF THE SURFACE WAVE AND COLD FRONT THIS
EVENING...WINDS WILL VEER TO THE NORTH AND NORTHWEST...BUT WILL
WEAKEN DURING THE DAY FRIDAY AS HIGH PRESSURE BUILDS INTO THE AREA
FOR THE WEEKEND. THE HIGH WILL DRIFT EAST OF LAKE MICHIGAN SUNDAY
WHILE LOW PRESSURE DEVELOPS FARTHER WEST ACROSS THE HIGH PLAINS.
THIS WILL RESULT IN A QUICK RETURN TO SOUTHERLY FLOW INTO EARLY
NEXT WEEK.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KILX 281744
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1244 PM CDT THU AUG 28 2008

.DISCUSSION...
ISSUED 1030 AM CDT THU AUG 28 2008

DECAYING MCS CONTINUES TO TRACK SLOWLY EASTWARD INTO CENTRAL
ILLINOIS THIS MORNING. IR SATELLITE TRENDS HAVE SHOWN A STEADY
INCREASE IN CLOUD TOP TEMPS...EXCEPT FOR A CLUSTER OF PERSISTENTLY
COLDER TOPS ON THE SOUTHWEST PERIPHERY OF THE COMPLEX. RADAR SHOWS
MAINLY LIGHT SHOWERS TRACKING EASTWARD THROUGH THE ILLINOIS RIVER
VALLEY...WITH THE MAIN CLUSTER OF STORMS FURTHER SOUTHWEST
STRETCHING FROM LEWISTOWN TO RUSHVILLE. PRECIP AREA WILL CONTINUE
TO DIMINISH AS IT PUSHES FURTHER EASTWARD TOWARD SURFACE RIDGE IN
PLACE ACROSS INDIANA. CURRENT FORECAST MENTIONS SCATTERED STORMS
ACROSS THE ILLINOIS RIVER VALLEY...WITH ONLY ISOLATED WORDING
ALONG THE I-55 CORRIDOR THIS MORNING. THINK THIS IS STILL PRETTY
MUCH ON TRACK...SO WILL NOT MAKE ANY CHANGES. WILL CONTINUE TO
MONITOR MAIN CLUSTER OF STORMS TO SEE IF IT ALSO FOLLOWS
DIMINISHING TREND OVER THE NEXT COUPLE OF HOURS. MAIN QUESTION IS
HOW MUCH DESTABILIZATION CAN TAKE PLACE THIS AFTERNOON ALONG AND
AHEAD OF COLD FRONT CURRENTLY IN PLACE ACROSS IOWA. BASED ON
EVOLUTION OF MORNING MCS AND AMOUNT OF CLOUD COVER...COVERAGE OF
AFTERNOON STORMS WILL LIKELY BE MINIMAL. CURRENT GRIDS FEATURE
ONLY CHANCE POPS THIS AFTERNOON ALONG AND WEST OF I-55...AND THINK
THIS STILL LOOKS GOOD. WILL MAKE A FEW CHANGES TO THE GRIDS AND
SEND OUT UPDATED ZONES SOON...MAINLY TO GET RID OF MORNING
WORDING.



&&

.AVIATION...
ISSUED 1244 PM CDT THU AUG 28 2008

REMNANTS OF MORNING MCS CONTINUE TO TRACK ACROSS CENTRAL ILLINOIS
EARLY THIS AFTERNOON...WITH BAND OF LIGHT RAIN SHOWERS CURRENTLY
EXTENDING FROM KCMI...TO KDEC...TO JUST SOUTH OF KSPI. ONCE THIS
PRECIP CLEARS THE TAF SITES IN THE NEXT HOUR OR SO...CONDITIONS
WILL REMAIN DRY UNTIL LATER THIS AFTERNOON INTO THE EVENING WHEN A
COLD FRONT BEGINS TO APPROACH FROM THE WEST. SCATTERED CONVECTION
IS EXPECTED TO DEVELOP IN ADVANCE OF THE FRONT ACROSS IOWA THIS
AFTERNOON...THEN PUSH INTO CENTRAL ILLINOIS TOWARD 00Z. WITH
STABLE AIRMASS IN PLACE ACROSS THE AREA...COVERAGE OF CONVECTION
REMAINS A BIG QUESTION. WILL THEREFORE ONLY MENTION VCTS IN THE
TAFS UNTIL EXACT CONVECTIVE TRENDS BECOME CLEARER. WINDS ARE
EXPECTED TO BE FROM THE SOUTH EARLY ON...BUT WILL SHIFT TO THE
W/NW DURING THE 03Z TO 06Z TIME FRAME. THANKS TO A DELAY IN THE
ARRIVAL OF DRIER AIR...AREAS OF FOG WILL LIKELY DEVELOP LATE
TONIGHT AS SKIES CLEAR. WILL INCLUDE TEMPO GROUPS FOR VISBYS DOWN
TO AROUND 2SM AT ALL SITES. AFTER THAT...LIGHT N/NE WINDS AND
CLEAR SKIES WILL PREVAIL FRIDAY MORNING.

BARNES
&&

.PREV DISCUSSION...
ISSUED 317 AM CDT THU AUG 28 2008
FRONT STILL ON APPROACH FROM THE NW THIS MORNING...THOUGH MASS OF
THUNDERSTORM ACTIVITY HAS NOW PUSHED OUT WELL AHEAD OF THE FRONT
ALONG AN OUTFLOW BOUNDARY. HIGH SFC PRESSURE SLIDING OFF TO THE
EAST AS MIDWEST CLOUDS UP AND WINDS COME AROUND FROM THE SOUTH.
MAIN ISSUE FOR THE FORECAST WILL BE THE FRONT AND THE ASSOCIATED
PRECIP...THOUGH FORECAST IS REALLY QUITE CONSISTENT WITH PREVIOUS
PACKAGES. BEYOND THE SHORT TERM...THE FORECAST ISSUES ARE ONLY
WITH TEMPERATURE.

SHORT TERM...TODAY AND TOMORROW...
A BIT OF PATCHY FOG IN PLACE ALONG INTERSTATE 57 AND POINTS EAST
THIS MORNING...SHOULD BURN OFF QUICKLY WITH THE SUNRISE. SOUTHERLY
WINDS SHOULD HELP BRING MAX TEMPS JUST A SMIDGE OVER YESTERDAYS
HIGHS FOR MOST AREAS SE OF THE ILLINOIS RIVER VALLEY.  FRONT WILL
APPROACH FROM THE NW BRINGING CHANCE POPS FIRST TO THE EXTREME NW
THIS MORNING...THEN PROGRESSING MORE TO THE IL RIVER VALLEY AND
I-55 CORRIDOR THIS EVENING. NAM/WRF MUCH SLOWER WITH THE FRONT
THAN THE GFS OR THE ECMWF...AND HAS CONSISTENTLY SPLIT THE
THUNDERSTORM ACTIVITY... PASSING SOME DOWN THE MISS RIVER
VALLEY...AND ANOTHER MASS OF STORMS ACROSS THE NRN PORTIONS OF THE
STATE...LEAVING LITTLE MORE THAN SOME SCATTERED ACTIVITY FOR THE
FA. HIGH CHANCE POPS AS GOOD AS IT WILL GET FOR NOT WITH BEST
CHANCES FOR PRECIP WILL BE IN THE OVERNIGHT HOURS AS THE FRONT
DRIVES THROUGH MUCH OF THE CWA. THAT BEING SAID...THUNDER HAS
SLIGHT RISK OF BEING SEVERE IN THE FAR NW IF TIMING OF FRONT
ASSOCIATED TS COINCIDES WITH DEEP LAYER SHEER THIS AFTERNOON.
FRONT MOVES SE...INVOF I 70 BY TOMORROW AFTERNOON. MODELS HAVE
HINTED REPEATEDLY ON THE FRONT REFIRING FRIDAY. TIMING AND
LOCATION WHEN THIS OCCURS IS KEY TO HOW LONG IT WILL BE WET ON
FRIDAY...BUT BOTH THE SLOWER NAM AND THE QUICKER GFS BOTH END THE
PRECIP BY 00Z.

LONG TERM...SATURDAY THROUGH SUNDAY...
SATURDAY THROUGH THE EARLY PART OF NEXT WEEK WILL BE DRY BEHIND THE
FRONT AS THE UPPER LEVEL RIDGE BEGINS TO BUILD OVER THE REGION
WITH RATHER SEASONABLE AND PLEASANT TEMPS FOR THE WEEKEND.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KILX 281530
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1030 AM CDT THU AUG 28 2008

.DISCUSSION...
ISSUED 1030 AM CDT THU AUG 28 2008

DECAYING MCS CONTINUES TO TRACK SLOWLY EASTWARD INTO CENTRAL
ILLINOIS THIS MORNING. IR SATELLITE TRENDS HAVE SHOWN A STEADY
INCREASE IN CLOUD TOP TEMPS...EXCEPT FOR A CLUSTER OF PERSISTENTLY
COLDER TOPS ON THE SOUTHWEST PERIPHERY OF THE COMPLEX. RADAR SHOWS
MAINLY LIGHT SHOWERS TRACKING EASTWARD THROUGH THE ILLINOIS RIVER
VALLEY...WITH THE MAIN CLUSTER OF STORMS FURTHER SOUTHWEST
STRETCHING FROM LEWISTOWN TO RUSHVILLE. PRECIP AREA WILL CONTINUE
TO DIMINISH AS IT PUSHES FURTHER EASTWARD TOWARD SURFACE RIDGE IN
PLACE ACROSS INDIANA. CURRENT FORECAST MENTIONS SCATTERED STORMS
ACROSS THE ILLINOIS RIVER VALLEY...WITH ONLY ISOLATED WORDING
ALONG THE I-55 CORRIDOR THIS MORNING. THINK THIS IS STILL PRETTY
MUCH ON TRACK...SO WILL NOT MAKE ANY CHANGES. WILL CONTINUE TO
MONITOR MAIN CLUSTER OF STORMS TO SEE IF IT ALSO FOLLOWS
DIMINISHING TREND OVER THE NEXT COUPLE OF HOURS. MAIN QUESTION IS
HOW MUCH DESTABILIZATION CAN TAKE PLACE THIS AFTERNOON ALONG AND
AHEAD OF COLD FRONT CURRENTLY IN PLACE ACROSS IOWA. BASED ON
EVOLUTION OF MORNING MCS AND AMOUNT OF CLOUD COVER...COVERAGE OF
AFTERNOON STORMS WILL LIKELY BE MINIMAL. CURRENT GRIDS FEATURE
ONLY CHANCE POPS THIS AFTERNOON ALONG AND WEST OF I-55...AND THINK
THIS STILL LOOKS GOOD. WILL MAKE A FEW CHANGES TO THE GRIDS AND
SEND OUT UPDATED ZONES SOON...MAINLY TO GET RID OF MORNING
WORDING.

BARNES
&&

.AVIATION...
ISSUED 545 AM CDT THU AUG 28 2008

MVFR TO LOCALLY LIFR CONDITIONS IN FOG ACRS THE EAST THIS MRNG
WITH CMI JUST RECENTLY GOING DOWN TO LESS THAN ONE MILE IN FOG.
SECOND AREA OF CONCERN IS WITH THE WEAKENING CONVECTION COMING
ACRS THE MISSISSIPPI RIVER THIS MRNG AND ANY AFFECT ON PIA AND
PSBLY SPI OVR THE NEXT FEW HOURS. MAIN THREAT FOR CONVECTION
WL OCCUR ALONG A COLD FRONT WHICH IS FORECAST TO PUSH INTO WRN
IL LATE THIS AFTN. A FEW OF THE HIGH RESOLUTION MODELS SUGGEST
THE CONVECTION WILL FORM JUST AHEAD OF THE COLD FRONT ACRS EXTREME
SE IOWA INTO WRN IL AND THEN SPLIT...WITH ONE AREA GOING TO OUR
NORTH...AND A STRONGER BAND OF CONVECTION SLIPPING TO OUR WEST
AND SOUTH THIS EVENING. WL CONTINUE WITH VCTS WORDING LATER THIS
AFTN INTO THIS EVENING UNTIL ANY REDEVELOPMENT BECOMES BETTER
DEFINED ALONG THE COLD FRONT.

WHAT CONVECTION THAT WE DO SEE LATE THIS AFTN AND EVENING SHOULD
CLEAR THE TAF SITES AFTR 04Z. SFC WNDS WL BE FROM THE SOUTHWEST
TODAY WITH SPEEDS OF ARND 10 KTS AND THEN BECOME NORTHWEST LATE
THIS EVENING AFTR FROPA. IF THE AREA DOES SEE SOME RAINFALL LATE
TODAY INTO THE EVENING HOURS OUR CHANCES WILL INCREASE FOR SOME
GROUND FOG TO FORM SHORTLY BEFORE SUNRISE FRIDAY.

SMITH
&&

.PREV DISCUSSION...
ISSUED 317 AM CDT THU AUG 28 2008
FRONT STILL ON APPROACH FROM THE NW THIS MORNING...THOUGH MASS OF
THUNDERSTORM ACTIVITY HAS NOW PUSHED OUT WELL AHEAD OF THE FRONT
ALONG AN OUTFLOW BOUNDARY. HIGH SFC PRESSURE SLIDING OFF TO THE
EAST AS MIDWEST CLOUDS UP AND WINDS COME AROUND FROM THE SOUTH.
MAIN ISSUE FOR THE FORECAST WILL BE THE FRONT AND THE ASSOCIATED
PRECIP...THOUGH FORECAST IS REALLY QUITE CONSISTENT WITH PREVIOUS
PACKAGES. BEYOND THE SHORT TERM...THE FORECAST ISSUES ARE ONLY
WITH TEMPERATURE.

SHORT TERM...TODAY AND TOMORROW...
A BIT OF PATCHY FOG IN PLACE ALONG INTERSTATE 57 AND POINTS EAST
THIS MORNING...SHOULD BURN OFF QUICKLY WITH THE SUNRISE. SOUTHERLY
WINDS SHOULD HELP BRING MAX TEMPS JUST A SMIDGE OVER YESTERDAYS
HIGHS FOR MOST AREAS SE OF THE ILLINOIS RIVER VALLEY.  FRONT WILL
APPROACH FROM THE NW BRINGING CHANCE POPS FIRST TO THE EXTREME NW
THIS MORNING...THEN PROGRESSING MORE TO THE IL RIVER VALLEY AND
I-55 CORRIDOR THIS EVENING. NAM/WRF MUCH SLOWER WITH THE FRONT
THAN THE GFS OR THE ECMWF...AND HAS CONSISTENTLY SPLIT THE
THUNDERSTORM ACTIVITY... PASSING SOME DOWN THE MISS RIVER
VALLEY...AND ANOTHER MASS OF STORMS ACROSS THE NRN PORTIONS OF THE
STATE...LEAVING LITTLE MORE THAN SOME SCATTERED ACTIVITY FOR THE
FA. HIGH CHANCE POPS AS GOOD AS IT WILL GET FOR NOT WITH BEST
CHANCES FOR PRECIP WILL BE IN THE OVERNIGHT HOURS AS THE FRONT
DRIVES THROUGH MUCH OF THE CWA. THAT BEING SAID...THUNDER HAS
SLIGHT RISK OF BEING SEVERE IN THE FAR NW IF TIMING OF FRONT
ASSOCIATED TS COINCIDES WITH DEEP LAYER SHEER THIS AFTERNOON.
FRONT MOVES SE...INVOF I 70 BY TOMORROW AFTERNOON. MODELS HAVE
HINTED REPEATEDLY ON THE FRONT REFIRING FRIDAY. TIMING AND
LOCATION WHEN THIS OCCURS IS KEY TO HOW LONG IT WILL BE WET ON
FRIDAY...BUT BOTH THE SLOWER NAM AND THE QUICKER GFS BOTH END THE
PRECIP BY 00Z.

LONG TERM...SATURDAY THROUGH SUNDAY...
SATURDAY THROUGH THE EARLY PART OF NEXT WEEK WILL BE DRY BEHIND THE
FRONT AS THE UPPER LEVEL RIDGE BEGINS TO BUILD OVER THE REGION
WITH RATHER SEASONABLE AND PLEASANT TEMPS FOR THE WEEKEND.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 281501
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1001 AM CDT THU AUG 28 2008

.DISCUSSION...
1001 AM CDT

STRONG 850MB WARM AIR ADVECTION NOTED ON 12Z PROFILER DATA WILL
SLIDE EASTWARD THIS MORNING ACROSS THE REGION. MODERATE RAIN
SHIELD EXTENDING NORTHEASTWARD ALONG THIS WAA WILL LIKELY CONTINUE
EASTWARD AS THE 850MB WINDS GO MORE WEST TO EAST INTO THE EARLY
AFTERNOON HOURS. SOME QUESTIONS REMAIN FOR THIS AFTERNOONS
CONVECTIVE POTENTIAL BEING MET DUE TO THE CURRENT SLUG OF RAIN
ACROSS NORTHEAST ILLINOIS. CURRENTLY STILL THINK THAT THERE SHOULD
BE ENOUGH MOISTURE...INSTABILITY AND LIFT FROM THE FRONT AND UPPER
LEVEL DYNAMICS THAT SHOWERS AND THUNDERSTORMS WILL REDEVELOP ALONG
AND AHEAD OF THE FRONT. WHETHER ANY CAN BECOME SEVERE REMAINS TO
BE SEEN AS THE 0-6KM WIND SHEAR WILL BE ON THE INCREASE AS A 500MB
JET STREAK ENTERS THE REGION. WITH ACARS SOUNDINGS OUT OF RFD AND
ORD SHOWING THE FREEZING LEVEL UP AROUND 14KFT...IT WILL TAKE SOME
VIGOROUS UPDRAFTS TO PRODUCE ANY SEVERE HAIL OR WINDS.

HALBACH

&&

.PREV DISCUSSION...

340 AM CDT

MAIN FORECAST CONCERN TODAY THROUGH THIS EVENING IS POTENTIAL FOR
SHOWERS AND THUNDERSTORMS AND SEVERE WEATHER.

A STRONG UPPER LEVEL STREAK OF 120-130 KNOTS SAMPLED IN LAST
EVENINGS RAOBS ACROSS MONTANA WILL CONTINUE TO PROGRESS THROUGH THE
BASE OF THE UPPER TROUGH THAT WILL AFFECT THE GREAT LAKES REGION
TODAY AND TONIGHT. SURFACE PRESSURE FALLS HAVE BEEN STRENGTHENING
OVERNIGHT ACROSS THE UPPER MS RIVER VALLEY WITH INCREASING LARGE
SCALE ASCENT AND BROAD LOW LEVEL ISENTROPIC. A FEW SHOWERS HAVE BEEN
TRYING TO DEVELOP THIS MORNING CLOSER TO THE MISSISSIPPI RIVER BUT
INSTABILITY IN THIS REGION OVERNIGHT HAS BEEN HIGHLY ELEVATED IN
NATURE. MORE IMPRESSIVE LOW LEVEL MOISTURE PROFILES REMAIN OFF TO
THE WEST THIS MORNING CLOSER TO THE LOW LEVEL FRONT SITUATED FROM
WESTERN/CENTRAL IOWA INTO NORTHWEST WISCONSIN. MORE WIDESPREAD
SHOWERS AND THUNDERSTORMS HAVE BEEN AFFECTING MUCH OF IOWA
OVERNIGHT...BUT AS LOW LEVEL JET VEERS MORE WESTERLY THIS
MORNING...AND AS ACTIVITY BEGINS TO MIGRATE AWAY FROM MAX
INSTABILITY AXIS SHOULD GRADUALLY SEE A DOWNWARD TREND IN INTENSITY
OF THESE SHOWERS AND THUNDERSTORMS. NONETHELESS...WILL LIKELY HAVE
SHOWERS AND SOME EMBEDDED THUNDER SURVIVE INTO NORTH CENTRAL
ILLINOIS EARLY THIS MORNING HAVE NUDGED UP POPS INTO LIKELY CATEGORY
FOR THIS MORNING. THUNDERSTORMS ARE EXPECTED TO REDEVELOP THIS
AFTERNOON AS LOW LEVEL THETA-E RIDGE IN ADVANCE OF THE FRONT
OVERSPREADS NORTH CENTRAL ILLINOIS WITH FORECAST SOUNDINGS SUGGEST
MLCAPES ON THE ORDER OF 1500-2000 J/KG AND DEEP LAYER SHEAR
MAGNITUDES UP AROUND 35-40 KNOTS ACROSS FAR NORTHERN ILLINOIS ON
SOUTHERN PERIPHERY OF AFOREMENTIONED UPPER JET STREAK ACROSS THE
UPPER MS RIVER VALLEY. BEST INSTABILITY IS EXPECTED TO SETUP THIS
AFTERNOON ACROSS NORTH CENTRAL ILLINOIS IN CLOSER PROXIMITY TO LOW
LEVEL THETA-E RIDGE...WITH INSTABILITY REMAINING MORE HIGHLY
ELEVATED AND LESSER IN MAGNITUDE ACROSS FAR NORTHEAST
ILLINOIS/NORTHWEST INDIANA SO WILL MAINTAIN ONLY CHANCE THUNDER
MENTION ACROSS NORTHEAST ILLINOIS TAPERING TO SLIGHT CHANCE ACROSS
MOST OF NWRN INDIANA COUNTIES. WITH MODERATE INSTABILITY AND
INCREASING DEEP LAYER SHEAR THIS AFTERNOON...A LOW END SEVERE THREAT
FOR HAIL/WINDS DOES APPEAR TO EXIST THIS AFTERNOON INTO EARLY THIS
EVENING ACROSS MUCH OF NORTH CENTRAL ILLINOIS PORTION OF THE CWA.
COMPLICATING FACTORS REGARDING THIS RISK WILL BE AMOUNT OF SURFACE
WARMING THAT CAN OCCUR FROM LEFTOVER DEBRIS FROM IOWA OVERNIGHT
CONVECTION. DESPITE POTENTIAL FOR CLOUDS LINGERING...WOULD SUSPECT
REACHING CONVEC TEMPS IN LOW TO MID 80S THIS AFTERNOON ACROSS NORTH
CENTRAL ILLINOIS WILL NOT BE A PROBLEM GIVEN INCREASING LOW LEVEL
MOISTURE.

BEST CHANCE OF THUNDER SHOULD BE LATE THIS AFTERNOON INTO THIS
EVENING WHEN LOW LEVEL CONVERGENCE MAXIMIZES WITH THE APPROACH OF
THE FRONT AND AS MAIN UPPER VORT MAX CURRENTLY MOVING THROUGH
CENTRAL SOUTH DAKOTA PROGRESSES THROUGH THE WESTERN GREAT LAKES.
BEST FORCING SHOULD REMAIN JUST NORTH OF THE AREA BUT SEE NO REASON
TO LOWER THE LIKELY POPS FOR THIS EVENING WITH LOW LEVEL CONVG ALONG
THE FRONT LIKELY SUFFICIENT TO MAINTAIN HIGH COVERAGE TO
SHOWERS/TSTORMS THIS EVENING. FRONT SHOULD BE EXITING SOUTHEAST
PORTIONS OF THE FORECAST AREA SHORTLY AFTER MIDNIGHT QUICKLY
ENDING PRECIP CHANCES. TEMPS TONIGHT SHOULD COOL BACK INTO THE MID
50S ACROSS FAR NWRN PORTIONS OF THE FORECAST AREA BEHIND THE FRONT
WITH CLEARING SKIES.

A DRY PLEASANT WEEKEND IS UPCOMING WITH BROAD SFC HIGH SETTLING OVER
THE GREAT LAKES. MODELS HAVE TRENDED OVER PAST FEW RUNS TO BE A BIT
QUICKER SHIFTING THE HIGH EASTWARD WITH A MORE RAPID WARMING TREND
SO DID NUDGE UP HIGHS A SHADE FOR THE WEEKEND. REST OF FORECAST LEFT
AS IS WITH WARM SUMMER-LIKE TEMPS EARLY NEXT WEEK AS AMPLIFIED
WESTERN CONUS TROUGH RESULTS IN RISING HEIGHTS ACROSS CENTRAL CONUS.

MARSILI

&&

.AVIATION...

628 AM CDT

FOR THE 1200 UTC TAFS...MAIN FORECAST PROBLEM IS WITH TIMING OF
PRECIP/CONVECTION ACROSS FORECAST AREA TODAY/THIS EVENING WITH
APPROACH OF COLD FRONT.

VIGOROUS SHORT WAVE TROUGH PUSHING FROM NORTHERN PLAINS TO UPPER
MIDWEST THIS MORNING...IN ASSOCIATION WITH 110+ KNOT UPPER JET
STREAK ACROSS THE DAKOTAS. IN THE LOWER LEVELS...SURFACE TROUGH
EXTENDS FROM NEAR KDLH...TO KMSP...KDSM EARLY THIS MORNING WITH
LOW LEVEL MOIST AXIS FROM KANSAS TO IOWA/SOUTHEAST MN. MOISTURE
CONVERGENCE/TRANSPORT ON NOSE 40 KNOT LOW LEVEL JET AROUND 850
HPA HAS LED TO DEVELOPMENT OF THUNDERSTORMS FROM IA/MN INTO
WESTERN WI/IL THIS MORNING. RUC MESOANALYSIS DATA INDICATES THIS
AREA OF CONVECTION IS MOVING OUT OF MOIST/ELEVATED INSTABILITY
AXIS INTO LESS FAVORABLE ENVIRONMENT ACROSS IL...THOUGH EXTENSIVE
STRATIFORM RAIN AREA WILL LIKELY MAKE SOME PROGRESS ACROSS
FORECAST AREA THIS MORNING WHILE DISSIPATING WITH WEAKENING OF
NOCTURNAL LOW LEVEL JET FORCING AND DECREASING INSTABILITY
FARTHER EAST. WITH THIS IN MIND WILL CARRY TEMPO SHOWERS AT KRFD
AND WILL MENTION VCSH AT CHICAGO AREA TERMINALS THIS MORNING.

AFTER DECAY/DISSIPATION OF MORNING PRECIP...FOCUS FOR ADDITIONAL
DEVELOPMENT SHOULD SHIFT BACK TO THE LOW LEVEL MOIST/INSTABILITY
AXIS AHEAD OF SURFACE FRONT. THIS MOVES INTO WESTERN PARTS OF
FORECAST AREA BY MID AFTERNOON...AND INTO NORTHEAST IL/NORTHWEST
IND LATE AFTERNOON/EVENING. THEREFORE WILL MAINTAIN TEMPO THUNDER
MENTION FROM 06Z FORECAST IN 21-01Z RANGE FOR KRFD AND 23-03Z FOR
CHI AREA. GIVEN SHALLOW BUT ABUNDANT LOW LEVEL MOISTURE NOTED IN
FORECAST SOUNDINGS IN FRONTAL ZONE...EXPECT MVFR VIS/CIG
CONDITIONS IN VCNTY THUNDERSTORMS...AND PERHAPS FOR A FEW HOURS
BEHIND FROPA. MORE VIGOROUS DRYING OF LOW LEVELS SHOULD HELP CLEAR
OUT ANY LOW CLOUDS/FOG EARLY FRIDAY MORNING.

AS FOR WINDS...LIGHT/VARIABLE BUT MAINLY SOUTHEAST WIND EARLY THIS
MORNING TO BECOME MORE SOUTHERLY WITH TIME AHEAD OF APPROACHING
SURFACE FRONT TODAY. BROAD TROUGH AXIS SUPPORTS GRADUAL SHIFT TO
SOUTHWEST/WEST AHEAD OF ACTUAL FRONT THIS AFTERNOON/EARLY EVENING
BEFORE VEERING NORTHWEST WITH ACTUAL FROPA TONIGHT. WEAKNESS OF
GRADIENT THIS MORNING OVER NORTHEAST IL COULD SUPPORT WEAK LAKE
BREEZE DEVELOPMENT EARLY...THOUGH NOT LIKELY TO PUSH THROUGH
TERMINALS AS SOUTH GRADIENT BECOMES A LITTLE STRONGER LATER THIS
MORNING/AFTERNOON.

RATZER

&&

.MARINE...

302 AM CDT

A COLD FRONT TRAILING FROM WEST OF HUDSON BAY INTO THE CENTRAL
PLAINS WILL BE THE FOCUS FOR SHORT TERM WEATHER CHANGES ACROSS
LAKE MICHIGAN THROUGH TONIGHT. A WEAK AREA OF LOW PRESSURE NEAR
OMAHA EARLY THIS MORNING WILL LIFT NORTHEAST ALONG THE FRONT AND
WILL MOVE ACROSS WISCONSIN AND LAKE MICHIGAN THROUGH THIS EVENING.
MODEST TIGHTENING OF THE PRESSURE GRADIENT AHEAD OF THIS FEATURE
WILL RESULT IN SOUTHERLY WINDS INCREASING THIS MORNING ACROSS THE
LAKE. WITH THE PASSAGE OF THE SURFACE WAVE AND COLD FRONT THIS
EVENING...WINDS WILL VEER TO THE NORTH AND NORTHWEST...BUT WILL
WEAKEN DURING THE DAY FRIDAY AS HIGH PRESSURE BUILDS INTO THE AREA
FOR THE WEEKEND. THE HIGH WILL DRIFT EAST OF LAKE MICHIGAN SUNDAY
WHILE LOW PRESSURE DEVELOPS FARTHER WEST ACROSS THE HIGH PLAINS.
THIS WILL RESULT IN A QUICK RETURN TO SOUTHERLY FLOW INTO EARLY
NEXT WEEK.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KLOT 281128
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
628 AM CDT THU AUG 28 2008

.DISCUSSION...

340 AM CDT

MAIN FORECAST CONCERN TODAY THROUGH THIS EVENING IS POTENTIAL FOR
SHOWERS AND THUNDERSTORMS AND SEVERE WEATHER.

A STRONG UPPER LEVEL STREAK OF 120-130 KNOTS SAMPLED IN LAST
EVENINGS RAOBS ACROSS MONTANA WILL CONTINUE TO PROGRESS THROUGH THE
BASE OF THE UPPER TROUGH THAT WILL AFFECT THE GREAT LAKES REGION
TODAY AND TONIGHT. SURFACE PRESSURE FALLS HAVE BEEN STRENGTHENING
OVERNIGHT ACROSS THE UPPER MS RIVER VALLEY WITH INCREASING LARGE
SCALE ASCENT AND BROAD LOW LEVEL ISENTROPIC. A FEW SHOWERS HAVE BEEN
TRYING TO DEVELOP THIS MORNING CLOSER TO THE MISSISSIPPI RIVER BUT
INSTABILITY IN THIS REGION OVERNIGHT HAS BEEN HIGHLY ELEVATED IN
NATURE. MORE IMPRESSIVE LOW LEVEL MOISTURE PROFILES REMAIN OFF TO
THE WEST THIS MORNING CLOSER TO THE LOW LEVEL FRONT SITUATED FROM
WESTERN/CENTRAL IOWA INTO NORTHWEST WISCONSIN. MORE WIDESPREAD
SHOWERS AND THUNDERSTORMS HAVE BEEN AFFECTING MUCH OF IOWA
OVERNIGHT...BUT AS LOW LEVEL JET VEERS MORE WESTERLY THIS
MORNING...AND AS ACTIVITY BEGINS TO MIGRATE AWAY FROM MAX
INSTABILITY AXIS SHOULD GRADUALLY SEE A DOWNWARD TREND IN INTENSITY
OF THESE SHOWERS AND THUNDERSTORMS. NONETHELESS...WILL LIKELY HAVE
SHOWERS AND SOME EMBEDDED THUNDER SURVIVE INTO NORTH CENTRAL
ILLINOIS EARLY THIS MORNING HAVE NUDGED UP POPS INTO LIKELY CATEGORY
FOR THIS MORNING. THUNDERSTORMS ARE EXPECTED TO REDEVELOP THIS
AFTERNOON AS LOW LEVEL THETA-E RIDGE IN ADVANCE OF THE FRONT
OVERSPREADS NORTH CENTRAL ILLINOIS WITH FORECAST SOUNDINGS SUGGEST
MLCAPES ON THE ORDER OF 1500-2000 J/KG AND DEEP LAYER SHEAR
MAGNITUDES UP AROUND 35-40 KNOTS ACROSS FAR NORTHERN ILLINOIS ON
SOUTHERN PERIPHERY OF AFOREMENTIONED UPPER JET STREAK ACROSS THE
UPPER MS RIVER VALLEY. BEST INSTABILITY IS EXPECTED TO SETUP THIS
AFTERNOON ACROSS NORTH CENTRAL ILLINOIS IN CLOSER PROXIMITY TO LOW
LEVEL THETA-E RIDGE...WITH INSTABILITY REMAINING MORE HIGHLY
ELEVATED AND LESSER IN MAGNITUDE ACROSS FAR NORTHEAST
ILLINOIS/NORTHWEST INDIANA SO WILL MAINTAIN ONLY CHANCE THUNDER
MENTION ACROSS NORTHEAST ILLINOIS TAPERING TO SLIGHT CHANCE ACROSS
MOST OF NWRN INDIANA COUNTIES. WITH MODERATE INSTABILITY AND
INCREASING DEEP LAYER SHEAR THIS AFTERNOON...A LOW END SEVERE THREAT
FOR HAIL/WINDS DOES APPEAR TO EXIST THIS AFTERNOON INTO EARLY THIS
EVENING ACROSS MUCH OF NORTH CENTRAL ILLINOIS PORTION OF THE CWA.
COMPLICATING FACTORS REGARDING THIS RISK WILL BE AMOUNT OF SURFACE
WARMING THAT CAN OCCUR FROM LEFTOVER DEBRIS FROM IOWA OVERNIGHT
CONVECTION. DESPITE POTENTIAL FOR CLOUDS LINGERING...WOULD SUSPECT
REACHING CONVEC TEMPS IN LOW TO MID 80S THIS AFTERNOON ACROSS NORTH
CENTRAL ILLINOIS WILL NOT BE A PROBLEM GIVEN INCREASING LOW LEVEL
MOISTURE.

BEST CHANCE OF THUNDER SHOULD BE LATE THIS AFTERNOON INTO THIS
EVENING WHEN LOW LEVEL CONVERGENCE MAXIMIZES WITH THE APPROACH OF
THE FRONT AND AS MAIN UPPER VORT MAX CURRENTLY MOVING THROUGH
CENTRAL SOUTH DAKOTA PROGRESSES THROUGH THE WESTERN GREAT LAKES.
BEST FORCING SHOULD REMAIN JUST NORTH OF THE AREA BUT SEE NO REASON
TO LOWER THE LIKELY POPS FOR THIS EVENING WITH LOW LEVEL CONVG ALONG
THE FRONT LIKELY SUFFICIENT TO MAINTAIN HIGH COVERAGE TO
SHOWERS/TSTORMS THIS EVENING. FRONT SHOULD BE EXITING SOUTHEAST
PORTIONS OF THE FORECAST AREA SHORTLY AFTER MIDNIGHT QUICKLY
ENDING PRECIP CHANCES. TEMPS TONIGHT SHOULD COOL BACK INTO THE MID
50S ACROSS FAR NWRN PORTIONS OF THE FORECAST AREA BEHIND THE FRONT
WITH CLEARING SKIES.

A DRY PLEASANT WEEKEND IS UPCOMING WITH BROAD SFC HIGH SETTLING OVER
THE GREAT LAKES. MODELS HAVE TRENDED OVER PAST FEW RUNS TO BE A BIT
QUICKER SHIFTING THE HIGH EASTWARD WITH A MORE RAPID WARMING TREND
SO DID NUDGE UP HIGHS A SHADE FOR THE WEEKEND. REST OF FORECAST LEFT
AS IS WITH WARM SUMMER-LIKE TEMPS EARLY NEXT WEEK AS AMPLIFIED
WESTERN CONUS TROUGH RESULTS IN RISING HEIGHTS ACROSS CENTRAL CONUS.

MARSILI

&&

.AVIATION...

628 AM CDT

FOR THE 1200 UTC TAFS...MAIN FORECAST PROBLEM IS WITH TIMING OF
PRECIP/CONVECTION ACROSS FORECAST AREA TODAY/THIS EVENING WITH
APPROACH OF COLD FRONT.

VIGOROUS SHORT WAVE TROUGH PUSHING FROM NORTHERN PLAINS TO UPPER
MIDWEST THIS MORNING...IN ASSOCIATION WITH 110+ KNOT UPPER JET
STREAK ACROSS THE DAKOTAS. IN THE LOWER LEVELS...SURFACE TROUGH
EXTENDS FROM NEAR KDLH...TO KMSP...KDSM EARLY THIS MORNING WITH
LOW LEVEL MOIST AXIS FROM KANSAS TO IOWA/SOUTHEAST MN. MOISTURE
CONVERGENCE/TRANSPORT ON NOSE 40 KNOT LOW LEVEL JET AROUND 850
HPA HAS LED TO DEVELOPMENT OF THUNDERSTORMS FROM IA/MN INTO
WESTERN WI/IL THIS MORNING. RUC MESOANALYSIS DATA INDICATES THIS
AREA OF CONVECTION IS MOVING OUT OF MOIST/ELEVATED INSTABILITY
AXIS INTO LESS FAVORABLE ENVIRONMENT ACROSS IL...THOUGH EXTENSIVE
STRATIFORM RAIN AREA WILL LIKELY MAKE SOME PROGRESS ACROSS
FORECAST AREA THIS MORNING WHILE DISSIPATING WITH WEAKENING OF
NOCTURNAL LOW LEVEL JET FORCING AND DECREASING INSTABILITY
FARTHER EAST. WITH THIS IN MIND WILL CARRY TEMPO SHOWERS AT KRFD
AND WILL MENTION VCSH AT CHICAGO AREA TERMINALS THIS MORNING.

AFTER DECAY/DISSIPATION OF MORNING PRECIP...FOCUS FOR ADDITIONAL
DEVELOPMENT SHOULD SHIFT BACK TO THE LOW LEVEL MOIST/INSTABILITY
AXIS AHEAD OF SURFACE FRONT. THIS MOVES INTO WESTERN PARTS OF
FORECAST AREA BY MID AFTERNOON...AND INTO NORTHEAST IL/NORTHWEST
IND LATE AFTERNOON/EVENING. THEREFORE WILL MAINTAIN TEMPO THUNDER
MENTION FROM 06Z FORECAST IN 21-01Z RANGE FOR KRFD AND 23-03Z FOR
CHI AREA. GIVEN SHALLOW BUT ABUNDANT LOW LEVEL MOISTURE NOTED IN
FORECAST SOUNDINGS IN FRONTAL ZONE...EXPECT MVFR VIS/CIG
CONDITIONS IN VCNTY THUNDERSTORMS...AND PERHAPS FOR A FEW HOURS
BEHIND FROPA. MORE VIGOROUS DRYING OF LOW LEVELS SHOULD HELP CLEAR
OUT ANY LOW CLOUDS/FOG EARLY FRIDAY MORNING.

AS FOR WINDS...LIGHT/VARIABLE BUT MAINLY SOUTHEAST WIND EARLY THIS
MORNING TO BECOME MORE SOUTHERLY WITH TIME AHEAD OF APPROACHING
SURFACE FRONT TODAY. BROAD TROUGH AXIS SUPPORTS GRADUAL SHIFT TO
SOUTHWEST/WEST AHEAD OF ACTUAL FRONT THIS AFTERNOON/EARLY EVENING
BEFORE VEERING NORTHWEST WITH ACTUAL FROPA TONIGHT. WEAKNESS OF
GRADIENT THIS MORNING OVER NORTHEAST IL COULD SUPPORT WEAK LAKE
BREEZE DEVELOPMENT EARLY...THOUGH NOT LIKELY TO PUSH THROUGH
TERMINALS AS SOUTH GRADIENT BECOMES A LITTLE STRONGER LATER THIS
MORNING/AFTERNOON.

RATZER

&&

.MARINE...

302 AM CDT

A COLD FRONT TRAILING FROM WEST OF HUDSON BAY INTO THE CENTRAL
PLAINS WILL BE THE FOCUS FOR SHORT TERM WEATHER CHANGES ACROSS
LAKE MICHIGAN THROUGH TONIGHT. A WEAK AREA OF LOW PRESSURE NEAR
OMAHA EARLY THIS MORNING WILL LIFT NORTHEAST ALONG THE FRONT AND
WILL MOVE ACROSS WISCONSIN AND LAKE MICHIGAN THROUGH THIS EVENING.
MODEST TIGHTENING OF THE PRESSURE GRADIENT AHEAD OF THIS FEATURE
WILL RESULT IN SOUTHERLY WINDS INCREASING THIS MORNING ACROSS THE
LAKE. WITH THE PASSAGE OF THE SURFACE WAVE AND COLD FRONT THIS
EVENING...WINDS WILL VEER TO THE NORTH AND NORTHWEST...BUT WILL
WEAKEN DURING THE DAY FRIDAY AS HIGH PRESSURE BUILDS INTO THE AREA
FOR THE WEEKEND. THE HIGH WILL DRIFT EAST OF LAKE MICHIGAN SUNDAY
WHILE LOW PRESSURE DEVELOPS FARTHER WEST ACROSS THE HIGH PLAINS.
THIS WILL RESULT IN A QUICK RETURN TO SOUTHERLY FLOW INTO EARLY
NEXT WEEK.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KILX 281049
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
549 AM CDT THU AUG 28 2008

.DISCUSSION...
ISSUED 317 AM CDT THU AUG 28 2008
FRONT STILL ON APPROACH FROM THE NW THIS MORNING...THOUGH MASS OF
THUNDERSTORM ACTIVITY HAS NOW PUSHED OUT WELL AHEAD OF THE FRONT
ALONG AN OUTFLOW BOUNDARY. HIGH SFC PRESSURE SLIDING OFF TO THE
EAST AS MIDWEST CLOUDS UP AND WINDS COME AROUND FROM THE SOUTH.
MAIN ISSUE FOR THE FORECAST WILL BE THE FRONT AND THE ASSOCIATED
PRECIP...THOUGH FORECAST IS REALLY QUITE CONSISTENT WITH PREVIOUS
PACKAGES. BEYOND THE SHORT TERM...THE FORECAST ISSUES ARE ONLY
WITH TEMPERATURE.

SHORT TERM...TODAY AND TOMORROW...
A BIT OF PATCHY FOG IN PLACE ALONG INTERSTATE 57 AND POINTS EAST
THIS MORNING...SHOULD BURN OFF QUICKLY WITH THE SUNRISE. SOUTHERLY
WINDS SHOULD HELP BRING MAX TEMPS JUST A SMIDGE OVER YESTERDAYS
HIGHS FOR MOST AREAS SE OF THE ILLINOIS RIVER VALLEY.  FRONT WILL
APPROACH FROM THE NW BRINGING CHANCE POPS FIRST TO THE EXTREME NW
THIS MORNING...THEN PROGRESSING MORE TO THE IL RIVER VALLEY AND
I-55 CORRIDOR THIS EVENING. NAM/WRF MUCH SLOWER WITH THE FRONT
THAN THE GFS OR THE ECMWF...AND HAS CONSISTENTLY SPLIT THE
THUNDERSTORM ACTIVITY... PASSING SOME DOWN THE MISS RIVER
VALLEY...AND ANOTHER MASS OF STORMS ACROSS THE NRN PORTIONS OF THE
STATE...LEAVING LITTLE MORE THAN SOME SCATTERED ACTIVITY FOR THE
FA. HIGH CHANCE POPS AS GOOD AS IT WILL GET FOR NOT WITH BEST
CHANCES FOR PRECIP WILL BE IN THE OVERNIGHT HOURS AS THE FRONT
DRIVES THROUGH MUCH OF THE CWA. THAT BEING SAID...THUNDER HAS
SLIGHT RISK OF BEING SEVERE IN THE FAR NW IF TIMING OF FRONT
ASSOCIATED TS COINCIDES WITH DEEP LAYER SHEER THIS AFTERNOON.
FRONT MOVES SE...INVOF I 70 BY TOMORROW AFTERNOON. MODELS HAVE
HINTED REPEATEDLY ON THE FRONT REFIRING FRIDAY. TIMING AND
LOCATION WHEN THIS OCCURS IS KEY TO HOW LONG IT WILL BE WET ON
FRIDAY...BUT BOTH THE SLOWER NAM AND THE QUICKER GFS BOTH END THE
PRECIP BY 00Z.

LONG TERM...SATURDAY THROUGH SUNDAY...
SATURDAY THROUGH THE EARLY PART OF NEXT WEEK WILL BE DRY BEHIND THE
FRONT AS THE UPPER LEVEL RIDGE BEGINS TO BUILD OVER THE REGION
WITH RATHER SEASONABLE AND PLEASANT TEMPS FOR THE WEEKEND.



&&

.AVIATION...
ISSUED 545 AM CDT THU AUG 28 2008

MVFR TO LOCALLY LIFR CONDITIONS IN FOG ACRS THE EAST THIS MRNG
WITH CMI JUST RECENTLY GOING DOWN TO LESS THAN ONE MILE IN FOG.
SECOND AREA OF CONCERN IS WITH THE WEAKENING CONVECTION COMING
ACRS THE MISSISSIPPI RIVER THIS MRNG AND ANY AFFECT ON PIA AND
PSBLY SPI OVR THE NEXT FEW HOURS. MAIN THREAT FOR CONVECTION
WL OCCUR ALONG A COLD FRONT WHICH IS FORECAST TO PUSH INTO WRN
IL LATE THIS AFTN. A FEW OF THE HIGH RESOLUTION MODELS SUGGEST
THE CONVECTION WILL FORM JUST AHEAD OF THE COLD FRONT ACRS EXTREME
SE IOWA INTO WRN IL AND THEN SPLIT...WITH ONE AREA GOING TO OUR
NORTH...AND A STRONGER BAND OF CONVECTION SLIPPING TO OUR WEST
AND SOUTH THIS EVENING. WL CONTINUE WITH VCTS WORDING LATER THIS
AFTN INTO THIS EVENING UNTIL ANY REDEVELOPMENT BECOMES BETTER
DEFINED ALONG THE COLD FRONT.

WHAT CONVECTION THAT WE DO SEE LATE THIS AFTN AND EVENING SHOULD
CLEAR THE TAF SITES AFTR 04Z. SFC WNDS WL BE FROM THE SOUTHWEST
TODAY WITH SPEEDS OF ARND 10 KTS AND THEN BECOME NORTHWEST LATE
THIS EVENING AFTR FROPA. IF THE AREA DOES SEE SOME RAINFALL LATE
TODAY INTO THE EVENING HOURS OUR CHANCES WILL INCREASE FOR SOME
GROUND FOG TO FORM SHORTLY BEFORE SUNRISE FRIDAY.

SMITH
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 280843
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
343 AM CDT THU AUG 28 2008

.DISCUSSION...

340 AM CDT

MAIN FORECAST CONCERN TODAY THROUGH THIS EVENING IS POTENTIAL FOR
SHOWERS AND THUNDERSTORMS AND SEVERE WEATHER.

A STRONG UPPER LEVEL STREAK OF 120-130 KNOTS SAMPLED IN LAST
EVENINGS RAOBS ACROSS MONTANA WILL CONTINUE TO PROGRESS THROUGH THE
BASE OF THE UPPER TROUGH THAT WILL AFFECT THE GREAT LAKES REGION
TODAY AND TONIGHT. SURFACE PRESSURE FALLS HAVE BEEN STRENGTHENING
OVERNIGHT ACROSS THE UPPER MS RIVER VALLEY WITH INCREASING LARGE
SCALE ASCENT AND BROAD LOW LEVEL ISENTROPIC. A FEW SHOWERS HAVE BEEN
TRYING TO DEVELOP THIS MORNING CLOSER TO THE MISSISSIPPI RIVER BUT
INSTABILITY IN THIS REGION OVERNIGHT HAS BEEN HIGHLY ELEVATED IN
NATURE. MORE IMPRESSIVE LOW LEVEL MOISTURE PROFILES REMAIN OFF TO
THE WEST THIS MORNING CLOSER TO THE LOW LEVEL FRONT SITUATED FROM
WESTERN/CENTRAL IOWA INTO NORTHWEST WISCONSIN. MORE WIDESPREAD
SHOWERS AND THUNDERSTORMS HAVE BEEN AFFECTING MUCH OF IOWA
OVERNIGHT...BUT AS LOW LEVEL JET VEERS MORE WESTERLY THIS
MORNING...AND AS ACTIVITY BEGINS TO MIGRATE AWAY FROM MAX
INSTABILITY AXIS SHOULD GRADUALLY SEE A DOWNWARD TREND IN INTENSITY
OF THESE SHOWERS AND THUNDERSTORMS. NONETHELESS...WILL LIKELY HAVE
SHOWERS AND SOME EMBEDDED THUNDER SURVIVE INTO NORTH CENTRAL
ILLINOIS EARLY THIS MORNING HAVE NUDGED UP POPS INTO LIKELY CATEGORY
FOR THIS MORNING. THUNDERSTORMS ARE EXPECTED TO REDEVELOP THIS
AFTERNOON AS LOW LEVEL THETA-E RIDGE IN ADVANCE OF THE FRONT
OVERSPREADS NORTH CENTRAL ILLINOIS WITH FORECAST SOUNDINGS SUGGEST
MLCAPES ON THE ORDER OF 1500-2000 J/KG AND DEEP LAYER SHEAR
MAGNITUDES UP AROUND 35-40 KNOTS ACROSS FAR NORTHERN ILLINOIS ON
SOUTHERN PERIPHERY OF AFOREMENTIONED UPPER JET STREAK ACROSS THE
UPPER MS RIVER VALLEY. BEST INSTABILITY IS EXPECTED TO SETUP THIS
AFTERNOON ACROSS NORTH CENTRAL ILLINOIS IN CLOSER PROXIMITY TO LOW
LEVEL THETA-E RIDGE...WITH INSTABILITY REMAINING MORE HIGHLY
ELEVATED AND LESSER IN MAGNITUDE ACROSS FAR NORTHEAST
ILLINOIS/NORTHWEST INDIANA SO WILL MAINTAIN ONLY CHANCE THUNDER
MENTION ACROSS NORTHEAST ILLINOIS TAPERING TO SLIGHT CHANCE ACROSS
MOST OF NWRN INDIANA COUNTIES. WITH MODERATE INSTABILITY AND
INCREASING DEEP LAYER SHEAR THIS AFTERNOON...A LOW END SEVERE THREAT
FOR HAIL/WINDS DOES APPEAR TO EXIST THIS AFTERNOON INTO EARLY THIS
EVENING ACROSS MUCH OF NORTH CENTRAL ILLINOIS PORTION OF THE CWA.
COMPLICATING FACTORS REGARDING THIS RISK WILL BE AMOUNT OF SURFACE
WARMING THAT CAN OCCUR FROM LEFTOVER DEBRIS FROM IOWA OVERNIGHT
CONVECTION. DESPITE POTENTIAL FOR CLOUDS LINGERING...WOULD SUSPECT
REACHING CONVEC TEMPS IN LOW TO MID 80S THIS AFTERNOON ACROSS NORTH
CENTRAL ILLINOIS WILL NOT BE A PROBLEM GIVEN INCREASING LOW LEVEL
MOISTURE.

BEST CHANCE OF THUNDER SHOULD BE LATE THIS AFTERNOON INTO THIS
EVENING WHEN LOW LEVEL CONVERGENCE MAXIMIZES WITH THE APPROACH OF
THE FRONT AND AS MAIN UPPER VORT MAX CURRENTLY MOVING THROUGH
CENTRAL SOUTH DAKOTA PROGRESSES THROUGH THE WESTERN GREAT LAKES.
BEST FORCING SHOULD REMAIN JUST NORTH OF THE AREA BUT SEE NO REASON
TO LOWER THE LIKELY POPS FOR THIS EVENING WITH LOW LEVEL CONVG ALONG
THE FRONT LIKELY SUFFICIENT TO MAINTAIN HIGH COVERAGE TO
SHOWERS/TSTORMS THIS EVENING. FRONT SHOULD BE EXITING SOUTHEAST
PORTIONS OF THE FORECAST AREA SHORTLY AFTER MIDNIGHT QUICKLY
ENDING PRECIP CHANCES. TEMPS TONIGHT SHOULD COOL BACK INTO THE MID
50S ACROSS FAR NWRN PORTIONS OF THE FORECAST AREA BEHIND THE FRONT
WITH CLEARING SKIES.

A DRY PLEASANT WEEKEND IS UPCOMING WITH BROAD SFC HIGH SETTLING OVER
THE GREAT LAKES. MODELS HAVE TRENDED OVER PAST FEW RUNS TO BE A BIT
QUICKER SHIFTING THE HIGH EASTWARD WITH A MORE RAPID WARMING TREND
SO DID NUDGE UP HIGHS A SHADE FOR THE WEEKEND. REST OF FORECAST LEFT
AS IS WITH WARM SUMMER-LIKE TEMPS EARLY NEXT WEEK AS AMPLIFIED
WESTERN CONUS TROUGH RESULTS IN RISING HEIGHTS ACROSS CENTRAL CONUS.

MARSILI

&&

.AVIATION...

1256 AM CDT

FOR THE 0600 UTC TAFS...MAIN FOCUS IS ON TIMING OF CONVECTION
POTENTIAL LATER TODAY/THIS EVENING WITH APPROACH OF SURFACE COLD
FRONT.

EVENING RAOB ANALYSIS DEPICTS STRONG SHORT WAVE TROUGH ACROSS THE
NORTHERN PLAINS...WITH SURFACE PRESSURE FALLS SPREADING ACROSS THE
UPPER MIDWEST IN RESPONSE TO THIS FEATURE. WHILE STRONGEST
MID/UPPER FORCING EXPECTED TO PROPAGATE ACROSS WI/UPPER MICHIGAN
LATER TODAY...LOW LEVEL MOISTURE RETURN ON SOUTH WINDS AHEAD OF
SURFACE TROUGH/COLD FRONT EXPECTED TO SUPPORT WEAK/MODERATE
INSTABILITY ACROSS ESPECIALLY WESTERN PORTIONS OF FORECAST AREA BY
THIS AFTERNOON AND EARLY EVENING. CURRENT CONVECTIVE ACTIVITY OVER
IOWA/MN EXPECTED TO WEAKEN LATER THIS MORNING AS IT MOVES AWAY
FROM BETTER LOW LEVEL MOISTURE/INSTABILITY AND NOCTURNAL LOW LEVEL
JET WEAKENS. NOT COMPLETELY OUT OF THE QUESTION THAT DYING
CONVECTION COULD MOVE INTO WESTERN PARTS OF FORECAST AREA...
ESPECIALLY FOR KRFD LATER THIS MORNING THOUGH CONFIDENCE OF
SHOWERS/STORMS MAINTAINING THEMSELVES THAT FAR EAST THIS MORNING
IS FAIRLY LOW. WHILE WILL LIKELY SEE INCREASE IN MID LEVEL CLOUDS
THIS THROUGH THIS MORNING...HIGHER PROBABILITY FOR THUNDER EXISTS
THIS AFTERNOON AS LOW LEVEL WINDS TURN MORE SOUTHERLY AND NARROW
AXIS OF 65+ DEG SURFACE DEW POINTS SURGE NORTHWARD INTO THE AREA.
THIS ALSO COINCIDES WITH TIMING OF BEST MID LEVEL FORCING ALONG
SOUTHERN PERIPHERY OF UPPER MIDWEST SHORT WAVE...AND ALSO APPEARS
TO COINCIDE WITH RIGHT ENTRANCE OF INITIAL UPPER JET STREAK WHICH
LIFTS NORTHEAST ACROSS THE UPPER MIDWEST THIS AFTERNOON. HAVE
LEANED TOWARD NAM MODEL FORECASTS FOR SURFACE PRESSURE FIELD AS
GFS APPEARS TO DEVELOP TOO STRONG OF A SURFACE WAVE IN RESPONSE TO
CONVECTION. WITH NAM SCENARIO...WOULD EXPECT CONVECTIVE THREAT TO
INCREASE ACROSS FAR WESTERN FORECAST AREA BY MID
AFTERNOON...SPREADING FARTHER EAST INTO CHICAGO AREA TERMINALS
LATE AFTERNOON/EVENING WITH BEST LOW LEVEL MOISTURE ADVECTION.
COMBINATION OF 1000-1500 J/KG MLCAPES...FRONTAL CONVERGENCE AND
MID/UPPER LEVEL FORCING WITH SHORT WAVE AND JET STREAK FEEL
CONFIDENT ENOUGH IN ADDING TEMPO GROUPS FOR TS. FRONTAL PASSAGE
DURING THE EVENING SHOULD END PRECIP CHANCES FROM THE WEST. MAY BE
A SHORT PERIOD OF MVFR CEILINGS BEHIND THE FRONT THIS EVENING
BEFORE LOW LEVEL DRYING SCOURS OUT LOWER CLOUDS OVERNIGHT.

AS FOR WINDS...LIGHT EAST/SOUTHEAST WINDS EARLY TO VEER SOUTHERLY
THIS MORNING...THEN SOUTHWEST THIS AFTERNOON. FROPA THIS EVENING
TO THEN SHIFT WINDS TO WEST/NORTHWEST FOR OVERNIGHT HOURS.

RATZER

&&

.MARINE...

302 AM CDT

A COLD FRONT TRAILING FROM WEST OF HUDSON BAY INTO THE CENTRAL
PLAINS WILL BE THE FOCUS FOR SHORT TERM WEATHER CHANGES ACROSS
LAKE MICHIGAN THROUGH TONIGHT. A WEAK AREA OF LOW PRESSURE NEAR
OMAHA EARLY THIS MORNING WILL LIFT NORTHEAST ALONG THE FRONT AND
WILL MOVE ACROSS WISCONSIN AND LAKE MICHIGAN THROUGH THIS EVENING.
MODEST TIGHTENING OF THE PRESSURE GRADIENT AHEAD OF THIS FEATURE
WILL RESULT IN SOUTHERLY WINDS INCREASING THIS MORNING ACROSS THE
LAKE. WITH THE PASSAGE OF THE SURFACE WAVE AND COLD FRONT THIS
EVENING...WINDS WILL VEER TO THE NORTH AND NORTHWEST...BUT WILL
WEAKEN DURING THE DAY FRIDAY AS HIGH PRESSURE BUILDS INTO THE AREA
FOR THE WEEKEND. THE HIGH WILL DRIFT EAST OF LAKE MICHIGAN SUNDAY
WHILE LOW PRESSURE DEVELOPS FARTHER WEST ACROSS THE HIGH PLAINS.
THIS WILL RESULT IN A QUICK RETURN TO SOUTHERLY FLOW INTO EARLY
NEXT WEEK.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KILX 280831
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
331 AM CDT THU AUG 28 2008

.DISCUSSION...
ISSUED 317 AM CDT THU AUG 28 2008
FRONT STILL ON APPROACH FROM THE NW THIS MORNING...THOUGH MASS OF
THUNDERSTORM ACTIVITY HAS NOW PUSHED OUT WELL AHEAD OF THE FRONT
ALONG AN OUTFLOW BOUNDARY. HIGH SFC PRESSURE SLIDING OFF TO THE
EAST AS MIDWEST CLOUDS UP AND WINDS COME AROUND FROM THE SOUTH.
MAIN ISSUE FOR THE FORECAST WILL BE THE FRONT AND THE ASSOCIATED
PRECIP...THOUGH FORECAST IS REALLY QUITE CONSISTENT WITH PREVIOUS
PACKAGES. BEYOND THE SHORT TERM...THE FORECAST ISSUES ARE ONLY
WITH TEMPERATURE.

SHORT TERM...TODAY AND TOMORROW...
A BIT OF PATCHY FOG IN PLACE ALONG INTERSTATE 57 AND POINTS EAST
THIS MORNING...SHOULD BURN OFF QUICKLY WITH THE SUNRISE. SOUTHERLY
WINDS SHOULD HELP BRING MAX TEMPS JUST A SMIDGE OVER YESTERDAYS
HIGHS FOR MOST AREAS SE OF THE ILLINOIS RIVER VALLEY.  FRONT WILL
APPROACH FROM THE NW BRINGING CHANCE POPS FIRST TO THE EXTREME NW
THIS MORNING...THEN PROGRESSING MORE TO THE IL RIVER VALLEY AND
I-55 CORRIDOR THIS EVENING. NAM/WRF MUCH SLOWER WITH THE FRONT
THAN THE GFS OR THE ECMWF...AND HAS CONSISTENTLY SPLIT THE
THUNDERSTORM ACTIVITY... PASSING SOME DOWN THE MISS RIVER
VALLEY...AND ANOTHER MASS OF STORMS ACROSS THE NRN PORTIONS OF THE
STATE...LEAVING LITTLE MORE THAN SOME SCATTERED ACTIVITY FOR THE
FA. HIGH CHANCE POPS AS GOOD AS IT WILL GET FOR NOT WITH BEST
CHANCES FOR PRECIP WILL BE IN THE OVERNIGHT HOURS AS THE FRONT
DRIVES THROUGH MUCH OF THE CWA. THAT BEING SAID...THUNDER HAS
SLIGHT RISK OF BEING SEVERE IN THE FAR NW IF TIMING OF FRONT
ASSOCIATED TS COINCIDES WITH DEEP LAYER SHEER THIS AFTERNOON.
FRONT MOVES SE...INVOF I 70 BY TOMORROW AFTERNOON. MODELS HAVE
HINTED REPEATEDLY ON THE FRONT REFIRING FRIDAY. TIMING AND
LOCATION WHEN THIS OCCURS IS KEY TO HOW LONG IT WILL BE WET ON
FRIDAY...BUT BOTH THE SLOWER NAM AND THE QUICKER GFS BOTH END THE
PRECIP BY 00Z.

LONG TERM...SATURDAY THROUGH SUNDAY...
SATURDAY THROUGH THE EARLY PART OF NEXT WEEK WILL BE DRY BEHIND THE
FRONT AS THE UPPER LEVEL RIDGE BEGINS TO BUILD OVER THE REGION
WITH RATHER SEASONABLE AND PLEASANT TEMPS FOR THE WEEKEND.

HJS
&&

.AVIATION...
ISSUED 1128 PM CDT WED AUG 27 2008...FOR THE 06Z TAFS

THE CONVECTIVE COMPLEX THAT WAS INDICATED BY GFS/NAM HAS DEVELOPED
IN W IOWA...AND CORFIDI VECTORS AND MEAN STORM LEVEL FLOW POINT
TOWARD AN ENE PROGRESSION THE REST OF THE NIGHT. THE NE TREND
SHOULD KEEP OUR AREA OUT OF THE PATH OF THE STRONGER STORMS BY
MORNING. PLUS...EXPECT A BIT OF WEAKENING WITH THE SYSTEM DURING
THE MORNING. STORMS SHOULD REDEVELOP ALONG THE FRONT LATER IN THE
AFTERNOON AND INTO EVENING ON THURSDAY. THE 00Z NAM IS KEEPING OUR
AREA DRY IN THE EVENING...WHILE THE GFS KEEPS THE STORMS ACTIVE
THROUGH 06Z. WILL GO WITH A WINDOW OF STORMS FROM LATE AFTERNOON
THROUGH MID EVENING FOR NOW. WILL USE VCTS TO ADD A MENTION
OUTSIDE THAT PERIOD OF TIME.

SOME LIGHT FOG HAS DEVELOPED IN CMI WITH 5SM BR...SO WILL KEEP
SOME FOG IN THE EASTERN TAFS...WHERE CLOUD COVER HAS NOT REACHED
YET. MVFR SHOULD BE AS LOW AND VIS LEVELS GET AT ANY ONE
POINT...ESPECIALLY WITH CI CLOUDS MOVING EASTWARD.

SHIMON
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 280802
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
302 AM CDT THU AUG 28 2008

.DISCUSSION...
257 PM CDT

REGION REMAINS UNDER THE INFLUENCE OF A SFC RIDGE THAT HAS BEEN
STRETCHED ACROSS THE GREAT LAKES FOR THE PAST FEW DAYS. WHILE
CONDITIONS WILL REMAIN PLEASANT OVERNIGHT...CLOUDS WILL BE ON THE
INCREASE AS THE NEXT SYSTEM ORGANIZES AND APPROACHES FROM THE WEST.

THIS SYSTEM OF NOTE IS A SHORT WAVE TROF CURRENTLY PROPAGATING
ACROSS EASTERN MONTANA INTO THE DAKOTAS. AS THIS SHORT WAVE TRACKS
EASTWARD INTO THE UPPER MISSISSIPPI VALLEY IT WILL PICK UP THE
REMAINS OF THE STALLED OUT SFC FRONTAL BOUNDARY AND PULL IT
EASTWARD INTO THE REGION THURSDAY INTO EARLY FRIDAY...WHICH WILL
BE THE MAIN FOCUS FOR ANY CONVECTION. THE ORIENTATION OF THE LOW
LEVEL WIND FIELD COMING OUT OF THE SOUTHWEST DOESNT APPEAR TO BE
THE GREATEST FOR MOISTURE ADVECTION OUT OF THE GULF...BUT
PRECIPITABLE WATER STILL IS EXPECTED TO INCREASE TO ABOVE AN INCH
AND A HALF BY THURSDAY AFTERNOON WHICH SHOULD BE SUFFICIENT FOR
PRECIP. THE DYNAMICS DO NOT APPEAR TO BE THERE FOR ANY ORGANIZED
SEVERE CONVECTION AS WIND SHEAR WILL BE RATHER LIMITED WITH SOME
MARGINAL ELEVATED MLCAPE OF AROUND 500 TO 1000 J/KG OF INSTABILITY
AVAILABLE FOR USE. ALSO...AM EXPECTING THE BEST FORCING TO BE
FURTHER NORTH CLOSER TO THE BETTER VORTICITY ADVECTION WITH THE
SHORT WAVE AND UPPER LEVEL FLOW. THE LOW LEVEL JET DOESNT HELP OUR
CAUSE OUT MUCH EITHER FOR NOCTURNAL CONVECTION WITH THE MAIN NOSE
POKING UP INTO THE UPPER GREAT LAKES. REGARDLESS...THERE SHOULD
STILL BE ENOUGH SYNOPTIC SCALE FORCING...INSTABILITY AND MOISTURE
FOR PRECIP TO OCCUR OUT AHEAD OF THIS FRONT. THEREFORE...BOOSTED
UP POPS A TAD FOR THURSDAY EVENING INTO THE EARLY MORNING HOURS ON
FRIDAY WITH FROPA WITH IT CLEARING AND DRYING OUT RATHER RAPIDLY
ON FRIDAY AS THE RIDGE BUILDS IN. TEMPERATURES SHOULD BE SLIGHTLY
WARMER ON THURSDAY WITH THE SOUTHWESTERLY FLOW OUT AHEAD OF THE
FRONT.

THEN THE RIDGE BUILDS IN FOR LABOR DAY WEEKEND AND PROVIDES
EVERYONE ACROSS THE REGION WITH NEAR PERFECT CONDITIONS FOR ANY
OUTDOOR ACTIVITIES WITH CLEAR SKIES...TEMPERATURES NEAR NORMAL AND
PRECIP CHANCES NEAR NIL THROUGHOUT THE HOLIDAY WEEKEND.

AS THE UPPER AND LOWER LEVEL RIDGE AXIS SLIDES EASTWARD ACROSS THE
MIDWEST...RETURN SOUTHWESTERLY FLOW WILL KICK IN TOWARD LABOR DAY
INTO EARLY NEXT WEEK WITH 850MB TEMPS CLIMBING UP TO AROUND 17-19C
BY TUESDAY. THIS SHOULD PUSH HIGH TEMPS INTO THE MID TO UPPER 80S
ACROSS THE REGION THROUGHOUT MOST OF THE EXTENDED PERIOD. THE NEXT
FEATURE OF INTEREST WILL BE A COLD FRONT COMING THROUGH AROUND
MIDWEEK. WENT MORE WITH THE TIMING OF THE 00/12Z ECMWF FOR
FROPA...WHICH BRINGS THE FRONT THROUGH AFTER WEDNESDAY...SO HAVE
KEPT THE EXTENDED PERIOD DRY AT THIS POINT. WHILE IT IS BEYOND THE
SCOPE OF THIS FORECAST PERIOD...SOMETHING THAT WILL BE WORTH
WATCHING IS THE REMNANTS OF GUSTAV AS IT TRACKS UP ALONG THE
MISSISSIPPI RIVER AND INTO THE REGION BY NEXT WEEKEND.

HALBACH

&&

.AVIATION...

1256 AM CDT

FOR THE 0600 UTC TAFS...MAIN FOCUS IS ON TIMING OF CONVECTION
POTENTIAL LATER TODAY/THIS EVENING WITH APPROACH OF SURFACE COLD
FRONT.

EVENING RAOB ANALYSIS DEPICTS STRONG SHORT WAVE TROUGH ACROSS THE
NORTHERN PLAINS...WITH SURFACE PRESSURE FALLS SPREADING ACROSS THE
UPPER MIDWEST IN RESPONSE TO THIS FEATURE. WHILE STRONGEST
MID/UPPER FORCING EXPECTED TO PROPAGATE ACROSS WI/UPPER MICHIGAN
LATER TODAY...LOW LEVEL MOISTURE RETURN ON SOUTH WINDS AHEAD OF
SURFACE TROUGH/COLD FRONT EXPECTED TO SUPPORT WEAK/MODERATE
INSTABILITY ACROSS ESPECIALLY WESTERN PORTIONS OF FORECAST AREA BY
THIS AFTERNOON AND EARLY EVENING. CURRENT CONVECTIVE ACTIVITY OVER
IOWA/MN EXPECTED TO WEAKEN LATER THIS MORNING AS IT MOVES AWAY
FROM BETTER LOW LEVEL MOISTURE/INSTABILITY AND NOCTURNAL LOW LEVEL
JET WEAKENS. NOT COMPLETELY OUT OF THE QUESTION THAT DYING
CONVECTION COULD MOVE INTO WESTERN PARTS OF FORECAST AREA...
ESPECIALLY FOR KRFD LATER THIS MORNING THOUGH CONFIDENCE OF
SHOWERS/STORMS MAINTAINING THEMSELVES THAT FAR EAST THIS MORNING
IS FAIRLY LOW. WHILE WILL LIKELY SEE INCREASE IN MID LEVEL CLOUDS
THIS THROUGH THIS MORNING...HIGHER PROBABILITY FOR THUNDER EXISTS
THIS AFTERNOON AS LOW LEVEL WINDS TURN MORE SOUTHERLY AND NARROW
AXIS OF 65+ DEG SURFACE DEW POINTS SURGE NORTHWARD INTO THE AREA.
THIS ALSO COINCIDES WITH TIMING OF BEST MID LEVEL FORCING ALONG
SOUTHERN PERIPHERY OF UPPER MIDWEST SHORT WAVE...AND ALSO APPEARS
TO COINCIDE WITH RIGHT ENTRANCE OF INITIAL UPPER JET STREAK WHICH
LIFTS NORTHEAST ACROSS THE UPPER MIDWEST THIS AFTERNOON. HAVE
LEANED TOWARD NAM MODEL FORECASTS FOR SURFACE PRESSURE FIELD AS
GFS APPEARS TO DEVELOP TOO STRONG OF A SURFACE WAVE IN RESPONSE TO
CONVECTION. WITH NAM SCENARIO...WOULD EXPECT CONVECTIVE THREAT TO
INCREASE ACROSS FAR WESTERN FORECAST AREA BY MID
AFTERNOON...SPREADING FARTHER EAST INTO CHICAGO AREA TERMINALS
LATE AFTERNOON/EVENING WITH BEST LOW LEVEL MOISTURE ADVECTION.
COMBINATION OF 1000-1500 J/KG MLCAPES...FRONTAL CONVERGENCE AND
MID/UPPER LEVEL FORCING WITH SHORT WAVE AND JET STREAK FEEL
CONFIDENT ENOUGH IN ADDING TEMPO GROUPS FOR TS. FRONTAL PASSAGE
DURING THE EVENING SHOULD END PRECIP CHANCES FROM THE WEST. MAY BE
A SHORT PERIOD OF MVFR CEILINGS BEHIND THE FRONT THIS EVENING
BEFORE LOW LEVEL DRYING SCOURS OUT LOWER CLOUDS OVERNIGHT.

AS FOR WINDS...LIGHT EAST/SOUTHEAST WINDS EARLY TO VEER SOUTHERLY
THIS MORNING...THEN SOUTHWEST THIS AFTERNOON. FROPA THIS EVENING
TO THEN SHIFT WINDS TO WEST/NORTHWEST FOR OVERNIGHT HOURS.

RATZER

&&

.MARINE...

302 AM CDT

A COLD FRONT TRAILING FROM WEST OF HUDSON BAY INTO THE CENTRAL
PLAINS WILL BE THE FOCUS FOR SHORT TERM WEATHER CHANGES ACROSS
LAKE MICHIGAN THROUGH TONIGHT. A WEAK AREA OF LOW PRESSURE NEAR
OMAHA EARLY THIS MORNING WILL LIFT NORTHEAST ALONG THE FRONT AND
WILL MOVE ACROSS WISCONSIN AND LAKE MICHIGAN THROUGH THIS EVENING.
MODEST TIGHTENING OF THE PRESSURE GRADIENT AHEAD OF THIS FEATURE
WILL RESULT IN SOUTHERLY WINDS INCREASING THIS MORNING ACROSS THE
LAKE. WITH THE PASSAGE OF THE SURFACE WAVE AND COLD FRONT THIS
EVENING...WINDS WILL VEER TO THE NORTH AND NORTHWEST...BUT WILL
WEAKEN DURING THE DAY FRIDAY AS HIGH PRESSURE BUILDS INTO THE AREA
FOR THE WEEKEND. THE HIGH WILL DRIFT EAST OF LAKE MICHIGAN SUNDAY
WHILE LOW PRESSURE DEVELOPS FARTHER WEST ACROSS THE HIGH PLAINS.
THIS WILL RESULT IN A QUICK RETURN TO SOUTHERLY FLOW INTO EARLY
NEXT WEEK.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KLOT 280556
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1256 AM CDT THU AUG 28 2008

.DISCUSSION...
257 PM CDT

REGION REMAINS UNDER THE INFLUENCE OF A SFC RIDGE THAT HAS BEEN
STRETCHED ACROSS THE GREAT LAKES FOR THE PAST FEW DAYS. WHILE
CONDITIONS WILL REMAIN PLEASANT OVERNIGHT...CLOUDS WILL BE ON THE
INCREASE AS THE NEXT SYSTEM ORGANIZES AND APPROACHES FROM THE WEST.

THIS SYSTEM OF NOTE IS A SHORT WAVE TROF CURRENTLY PROPAGATING
ACROSS EASTERN MONTANA INTO THE DAKOTAS. AS THIS SHORT WAVE TRACKS
EASTWARD INTO THE UPPER MISSISSIPPI VALLEY IT WILL PICK UP THE
REMAINS OF THE STALLED OUT SFC FRONTAL BOUNDARY AND PULL IT
EASTWARD INTO THE REGION THURSDAY INTO EARLY FRIDAY...WHICH WILL
BE THE MAIN FOCUS FOR ANY CONVECTION. THE ORIENTATION OF THE LOW
LEVEL WIND FIELD COMING OUT OF THE SOUTHWEST DOESNT APPEAR TO BE
THE GREATEST FOR MOISTURE ADVECTION OUT OF THE GULF...BUT
PRECIPITABLE WATER STILL IS EXPECTED TO INCREASE TO ABOVE AN INCH
AND A HALF BY THURSDAY AFTERNOON WHICH SHOULD BE SUFFICIENT FOR
PRECIP. THE DYNAMICS DO NOT APPEAR TO BE THERE FOR ANY ORGANIZED
SEVERE CONVECTION AS WIND SHEAR WILL BE RATHER LIMITED WITH SOME
MARGINAL ELEVATED MLCAPE OF AROUND 500 TO 1000 J/KG OF INSTABILITY
AVAILABLE FOR USE. ALSO...AM EXPECTING THE BEST FORCING TO BE
FURTHER NORTH CLOSER TO THE BETTER VORTICITY ADVECTION WITH THE
SHORT WAVE AND UPPER LEVEL FLOW. THE LOW LEVEL JET DOESNT HELP OUR
CAUSE OUT MUCH EITHER FOR NOCTURNAL CONVECTION WITH THE MAIN NOSE
POKING UP INTO THE UPPER GREAT LAKES. REGARDLESS...THERE SHOULD
STILL BE ENOUGH SYNOPTIC SCALE FORCING...INSTABILITY AND MOISTURE
FOR PRECIP TO OCCUR OUT AHEAD OF THIS FRONT. THEREFORE...BOOSTED
UP POPS A TAD FOR THURSDAY EVENING INTO THE EARLY MORNING HOURS ON
FRIDAY WITH FROPA WITH IT CLEARING AND DRYING OUT RATHER RAPIDLY
ON FRIDAY AS THE RIDGE BUILDS IN. TEMPERATURES SHOULD BE SLIGHTLY
WARMER ON THURSDAY WITH THE SOUTHWESTERLY FLOW OUT AHEAD OF THE
FRONT.

THEN THE RIDGE BUILDS IN FOR LABOR DAY WEEKEND AND PROVIDES
EVERYONE ACROSS THE REGION WITH NEAR PERFECT CONDITIONS FOR ANY
OUTDOOR ACTIVITIES WITH CLEAR SKIES...TEMPERATURES NEAR NORMAL AND
PRECIP CHANCES NEAR NIL THROUGHOUT THE HOLIDAY WEEKEND.

AS THE UPPER AND LOWER LEVEL RIDGE AXIS SLIDES EASTWARD ACROSS THE
MIDWEST...RETURN SOUTHWESTERLY FLOW WILL KICK IN TOWARD LABOR DAY
INTO EARLY NEXT WEEK WITH 850MB TEMPS CLIMBING UP TO AROUND 17-19C
BY TUESDAY. THIS SHOULD PUSH HIGH TEMPS INTO THE MID TO UPPER 80S
ACROSS THE REGION THROUGHOUT MOST OF THE EXTENDED PERIOD. THE NEXT
FEATURE OF INTEREST WILL BE A COLD FRONT COMING THROUGH AROUND
MIDWEEK. WENT MORE WITH THE TIMING OF THE 00/12Z ECMWF FOR
FROPA...WHICH BRINGS THE FRONT THROUGH AFTER WEDNESDAY...SO HAVE
KEPT THE EXTENDED PERIOD DRY AT THIS POINT. WHILE IT IS BEYOND THE
SCOPE OF THIS FORECAST PERIOD...SOMETHING THAT WILL BE WORTH
WATCHING IS THE REMNANTS OF GUSTAV AS IT TRACKS UP ALONG THE
MISSISSIPPI RIVER AND INTO THE REGION BY NEXT WEEKEND.

HALBACH

&&

.AVIATION...

1256 AM CDT

FOR THE 0600 UTC TAFS...MAIN FOCUS IS ON TIMING OF CONVECTION
POTENTIAL LATER TODAY/THIS EVENING WITH APPROACH OF SURFACE COLD
FRONT.

EVENING RAOB ANALYSIS DEPICTS STRONG SHORT WAVE TROUGH ACROSS THE
NORTHERN PLAINS...WITH SURFACE PRESSURE FALLS SPREADING ACROSS THE
UPPER MIDWEST IN RESPONSE TO THIS FEATURE. WHILE STRONGEST
MID/UPPER FORCING EXPECTED TO PROPAGATE ACROSS WI/UPPER MICHIGAN
LATER TODAY...LOW LEVEL MOISTURE RETURN ON SOUTH WINDS AHEAD OF
SURFACE TROUGH/COLD FRONT EXPECTED TO SUPPORT WEAK/MODERATE
INSTABILITY ACROSS ESPECIALLY WESTERN PORTIONS OF FORECAST AREA BY
THIS AFTERNOON AND EARLY EVENING. CURRENT CONVECTIVE ACTIVITY OVER
IOWA/MN EXPECTED TO WEAKEN LATER THIS MORNING AS IT MOVES AWAY
FROM BETTER LOW LEVEL MOISTURE/INSTABILITY AND NOCTURNAL LOW LEVEL
JET WEAKENS. NOT COMPLETELY OUT OF THE QUESTION THAT DYING
CONVECTION COULD MOVE INTO WESTERN PARTS OF FORECAST AREA...
ESPECIALLY FOR KRFD LATER THIS MORNING THOUGH CONFIDENCE OF
SHOWERS/STORMS MAINTAINING THEMSELVES THAT FAR EAST THIS MORNING
IS FAIRLY LOW. WHILE WILL LIKELY SEE INCREASE IN MID LEVEL CLOUDS
THIS THROUGH THIS MORNING...HIGHER PROBABILITY FOR THUNDER EXISTS
THIS AFTERNOON AS LOW LEVEL WINDS TURN MORE SOUTHERLY AND NARROW
AXIS OF 65+ DEG SURFACE DEW POINTS SURGE NORTHWARD INTO THE AREA.
THIS ALSO COINCIDES WITH TIMING OF BEST MID LEVEL FORCING ALONG
SOUTHERN PERIPHERY OF UPPER MIDWEST SHORT WAVE...AND ALSO APPEARS
TO COINCIDE WITH RIGHT ENTRANCE OF INITIAL UPPER JET STREAK WHICH
LIFTS NORTHEAST ACROSS THE UPPER MIDWEST THIS AFTERNOON. HAVE
LEANED TOWARD NAM MODEL FORECASTS FOR SURFACE PRESSURE FIELD AS
GFS APPEARS TO DEVELOP TOO STRONG OF A SURFACE WAVE IN RESPONSE TO
CONVECTION. WITH NAM SCENARIO...WOULD EXPECT CONVECTIVE THREAT TO
INCREASE ACROSS FAR WESTERN FORECAST AREA BY MID
AFTERNOON...SPREADING FARTHER EAST INTO CHICAGO AREA TERMINALS
LATE AFTERNOON/EVENING WITH BEST LOW LEVEL MOISTURE ADVECTION.
COMBINATION OF 1000-1500 J/KG MLCAPES...FRONTAL CONVERGENCE AND
MID/UPPER LEVEL FORCING WITH SHORT WAVE AND JET STREAK FEEL
CONFIDENT ENOUGH IN ADDING TEMPO GROUPS FOR TS. FRONTAL PASSAGE
DURING THE EVENING SHOULD END PRECIP CHANCES FROM THE WEST. MAY BE
A SHORT PERIOD OF MVFR CEILINGS BEHIND THE FRONT THIS EVENING
BEFORE LOW LEVEL DRYING SCOURS OUT LOWER CLOUDS OVERNIGHT.

AS FOR WINDS...LIGHT EAST/SOUTHEAST WINDS EARLY TO VEER SOUTHERLY
THIS MORNING...THEN SOUTHWEST THIS AFTERNOON. FROPA THIS EVENING
TO THEN SHIFT WINDS TO WEST/NORTHWEST FOR OVERNIGHT HOURS.


RATZER

&&

.MARINE...

1245 PM CDT

HIGH PRESSURE OVER THE SAINT LAWRENCE VALLEY WILL CONTINUE TO DRIFT
EAST ACROSS NORTHERN NEW ENGLAND...WHILE A RIDGE EXTENDS WESTWARD
ACROSS THE UPPER GREAT LAKES. MEANWHILE...A DEEP LOW PRESSURE OVER
NORTHERN MANITOBA WILL LIFT NORTH ALONG THE WESTERN SHORE OF HUDSON
BAY. THIS WILL RESULT IN LIGHT EAST TO SOUTHEAST WINDS VEERING TO
SOUTH BY EARLY THURSDAY...AND INCREASING DURING THURSDAY AS
PRESSURES FALL AHEAD OF THE COLD FRONT ASSOCIATED WITH THIS LOW.
THIS FRONT WILL WEAKEN AS IT MOVES ACROSS THE UPPER MISSISSIPPI
VALLEY TONIGHT. MEANWHILE...A WEAK LOW PRESSURE CENTER IS FORECAST
TO DEVELOP ALONG THE WESTERN EXTENSION OF THE FRONT TONIGHT...THEN
RIPPLE NORTHEASTWARD ON THURSDAY...REACHING CENTRAL OR SOUTHERN LAKE
MICHIGAN THURSDAY NIGHT.  IN THE WAKE OF THIS LOW...A HIGH PRESSURE
WILL BUILD ACROSS THE SOUTHERN GREAT LAKES FRIDAY NIGHT AND
SATURDAY...AND REMAIN IN PLACE OVER THE UPCOMING WEEKEND.

MERZLOCK

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KILX 280428
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1