Flash Flood Warning 10, NWS Chicago, IL

000 
WGUS73 KLOT 210100
FFSLOT
ILC007-037-089-103-111-141-201-210345-

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
751 PM CDT THU MAY 20 2004

THE FLASH FLOOD WARNING CONTINUES FOR WINNEBAGO COUNTY THROUGH 830 
PM CDT. 

THE FLASH FLOOD WARNING CONTINUES FOR BOONE AND MCHENRY COUNTIES 
THROUGH 10:15 CDT. 

THE FLASH FLOOD WARNING CONTINUES FOR LEE...OGLE...DEKALB AND KANE 
COUNTIES THROUGH 10:30 CDT. 

AT 751 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
HEAVY RAINS CONTINUING FROM DIXON ILLINOIS TO ELGIN ILLINOIS. THE 
RADAR HAS BEEN ESTIMATING RAINFALLS OF UP TO 3 TO 4 INCHES AN HOUR 
IN SOME OF THESE SLOW MOVING THUNDERSTORMS. 

THE TOWNS OF WOODSTOCK...WONDER LAKE...WINNEBAGO...WEST DUNDEE AND
WATERMAN ARE IN THE AREA OF THIS FLOODING.

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF IN A FLOOD PRONE AREA...MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG CREEKS AND STREAMS ARE ESPECIALLY VULNERABLE
TO THE EFFECTS OF FLASH FLOODING. 

EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING ON FLOOD PRONE
HIGHWAYS...STREETS AND UNDERPASSES. NEVER WALK OR DRIVE INTO FLOODED
AREAS AND ABANDON VEHICLES CAUGHT IN RISING WATERS.

MOST DEATHS IN FLASH FLOODING OCCUR IN AUTOMOBILES. DO NOT DRIVE YOUR
VEHICLE INTO AREAS IN WHICH WATER COVERS THE ROADWAY. IT ONLY TAKES
TWO FEET OF WATER TO WASH MOST VEHICLES AWAY INCLUDING SUVS AND
PICKUPS. VEHICLES CAUGHT IN RISING WATERS SHOULD BE ABANDONED
QUICKLY.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLASH FLOODS. IT IS VERY DIFFICULT AT NIGHT TO JUDGE HOW
MUCH WATER COVERS ROADWAYS. DO NOT ATTEMPT TO CROSS FLOODED ROADWAYS.

REPORT FLASH FLOODING TO YOUR LOCAL ESDA...OR THE NEAREST LAW
ENFORCEMENT AGENCY...FOR RELAY TO THE NATIONAL WEATHER SERVICE. STAY
TUNED FOR LATER STATEMENTS.

LAT...LON 4244 8932 4162 8960 4178 8832 4245 8824
$$

WILSON

NNNN

000 
WGUS73 KLOT 210130
FFSLOT
ILC201-210145-

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
830 PM CDT THU MAY 20 2004

...THE FLASH FLOOD WARNING IN EFFECT FOR WINNEBAGO COUNTY HAS 
EXPIRED...

THE HEAVY RAINFALL AND FLOOD THREAT HAS ENDED ACROSS THE WARNED 
AREA. THEREFORE...THE FLASH FLOOD WARNING HAS BEEN ALLOWED TO 
EXPIRE.

EMERGENCY MANAGEMENT IN WINNEBAGO COUNTY REPORTS THE FLOODING IN THE 
DURAND AREA EARLIER THIS EVENING...HAS SUBSIDED AND NO ADDITIONAL 
FLOODING IS EXPECTED.

LAT...LON 4247 8898 4235 8899 4236 8935 4247 8937
$$

NNNN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
330 PM CDT THU MAY 20 2004

.DISCUSSION FOR AFTERNOON GRIDS...

MAJOR CONCERNS FOR THIS FORECAST WILL CENTER ON SEVERE WEATHER
CHANCES AND HEAVY RAINFALL POTENTIAL.

SYNOPTIC SCALE COLD FRONTAL BOUNDARY AT 19Z EXTENDS FROM NORTHERN
LAKE MICHIGAN SOUTHWEST INTO EAST CENTRAL IOWA. AXIS OF SURFACE
PRESSURE RISES ON ORDER OF 2-4 MB BEHIND THIS BOUNDARY AND SHOULD
CONTINUE TO SEE BOUNDARY SAG SOUTHWARD THIS EVENING AND HIGHLY
SHEARED NORTHERN STREAM VORT MAX ACROSS FAR SOUTHERN CANADA
CONTINUES TO PUSH EAST. ANOTHER VORT MAX WHICH WILL HAVE TO BE
WATCHED THIS EVENING IS CURRENTLY LOCATED ACROSS SOUTHWEST IOWA AND
THIS WAVE SHOULD CONTINUE TO LIFT NORTHEAST THIS EVENING INTO
NORTHWEST ILLINOIS. PLENTY OF ACCAS NOTED IN VIS IMAGERY ACROSS
CENTRAL/EASTERN IOWA EXTENDING INTO NORTHWEST ILLINOIS. RUC
SOUNDINGS/SPC MESO ANALYSIS/AND SPECIAL 18Z SOUNDING FROM KDVN
INDICATING CAP STRENGTH HAS SIGNIFICANTLY WEAKENED BENEATH MID/UPPER
LEVEL ELEVATED MIXED LAYER WITH STRONGER CAP REMAINING IN PLACE IN
STRONGER MID LEVEL THERMAL RIDGE ACROSS CENTRAL IL. SB CAPES BETWEEN
4000-5000 J/KG ACROSS CWA WITH PLENTY OF DEEP LAYER SHEAR TO WORK
WITH. AS SW IOWA WAVE CONTINUES TO LIFT INTO CWA TONIGHT...EXPECT
CONTINUED MID LEVEL COOLING AND INITIATION OF THUNDERSTORMS SOMETIME
IN THE 21Z-23Z TIME FRAME. SHEAR AND INSTABILITY SUPPORT SEVERE
WEATHER TONIGHT...AND HEAVY RAIN ALSO A CONCERN WITH PWATS POOLING
UP TO AROUND 1.75 INCHES AHEAD OF MAIN SYNOPTIC BOUNDARY. WILL
CONTINUE FLOOD WATCH THROUGH 17Z FRIDAY GIVEN SEVERAL LOCATIONS
ACROSS FAR NE IL AT OR ABOVE FLOOD STAGE FROM PREVIOUS HEAVY RAINS.
BOUNDARY WILL DROP INTO SOUTHERN PORTIONS OF CWA LATE THIS
EVENING...BUT RUC/MESOETA STILL DEPICTING LOW LEVEL WAA ACROSS CWA
NORTH OF SURFACE BOUNDARY.

ON FRIDAY LOW LEVEL BAROCLINIC ZONE WILL LIFT NORTHWARD INTO
SOUTHERN WISCONSIN PUTTING CWA BACK IN WARM SECTOR. TEMPS SHOULD
EASILY WARM INTO MID TO UPPER 80S ACROSS SOUTHERN PORTIONS OF CWA.
GIVEN UNSTABLE AIR SOUTH OF THIS BOUNDARY WILL RETAIN CHANCE POPS
NORTH OF INTERSTATE 88 INTO THE AFTERNOON AS MID LEVEL RIDGE
BUILDS BACK INTO CENTRAL ILLINOIS LIMITING CONVECTIVE CHANCES ACROSS
SOUTHERN CWA. FOCUS FOR CONVECTIVE ACTIVITY SHOULD REMAIN NORTH OF
CWA DURING THE DAY SATURDAY BUT CONVECTIVE CHANCES BEGIN TO INCREASE
AGAIN SATURDAY NIGHT INTO SUNDAY AS STRONGER MID LEVEL WAVE IS
PROGGED TO EJECT NORTHEAST OUT OF THE CENTRAL PLAINS. SOME
INDICATIONS OF POSSIBLE UPPER JET COUPLING BETWEEN NORTHERN/SOUTHERN
STREAMS LATE FRIDAY AS THIS MID LEVEL WAVE APPROACHES. WILL KEEP ESF
GOING TO MENTION POSSIBILITY OF HEAVY RAIN THROUGH SUNDAY.

WEAK COLD FRONT SHOULD PUSH THROUGH CWA MONDAY MORNING BRINGING END
TO RAIN CHANCES BEFORE NEXT LOW LEVEL MOISTURE RETURNS LATE MONDAY
INTO TUESDAY WITH NEXT MID LEVEL WAVE. WILL KEEP CHANCE FOR TUESDAY
AND KEEP MONDAY DRY UNTIL BETTER CONSISTENCY BECOMES ESTABLISHED.
TREND TO THURSDAY LOOKS TO BE FOR COOLER TEMPERATURES AS WESTERN
CONUS LONGWAVE TROUGH AMPLIFIES BRINGING COOLER AIR BEHIND YET
ANOTHER POSSIBLE SHORT WAVE PASSAGE FOR MID WEEK. WILL ALSO KEEP
WED/THU DRY FOR NOW.

NDM

&&

.AVIATION...

THE SOUNDINGS SEEN ON ACARS AT ORD AT 1610 UTC SHOWS AN NEAR
ISOTHERMAL LAYER AT 8000 FT. THE INVERSION SEEN ON THE EARLIER
SOUNDINGS ARE SLOWLY MIXING OUT. WILL SLOWLY RAISE THE MVFR CEILING
TO VFR LATE THIS AFTERNOOON. WILL ADD THUNDERSTORMS TO THE TAFS
FORECASTS. AS THE MCS THIS MORNING HAS LONG GONE EAST. THE
SUBSIDENCE BEHIND THE MCS WILL NOT SLOWLY LEAVE AND WE WILL
SEE SOME MOVE VETICAL LIFT AND MIXING. THE AIR IS UNSTABLE WITH
PLENTY OF LOW LEVEL MOISTURE. AFTER THE FRONT PASSES SOUTH NORTHEAST
WIND WILL PREVAIL. WILL KEEP LOW MVFR CIELINGS AS THERE WILL BE
PLENTY OF LOW LEVEL MOISTURE...AN INVERSION AND ISNETROPIC LIFT.
THE NORTHEAST WINDS WILL BRING IN A LITTLE LAKE MOISTURE AND ENHANCE
THE COOL AIR MASS WITH LAKE MICHIGAN AIR AS WELL. WHW

&&

.LOT...WATCHES/WARNINGS/ADVISORIES...
IL...FLOOD WATCH ALL OF IL CWA THROUGH 17Z FRIDAY.
IN...FLOOD WATCH PORTER...LAKE...NEWTON...JASPER...BENTON COUNTIES
     THROUGH 17Z FRIDAY.
LK MI...NONE.

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE CHICAGO IL
343 PM CDT THU MAY 20 2004

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-
019-211100-
BENTON-BOONE-COOK-DE KALB-DU PAGE-FORD-GRUNDY-IROQUOIS-JASPER-
KANE-KANKAKEE-KENDALL-LA SALLE-LAKE-LAKE IN-LEE-LIVINGSTON-
MCHENRY-NEWTON-OGLE-PORTER-WILL-WINNEBAGO-
343 PM CDT THU MAY 20 2004

THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR NORTH
CENTRAL AND NORTHEAST ILLINOIS...AND NORTHWEST INDIANA.

.DAY ONE...TODAY AND TONIGHT

A FLOOD WATCH IS IN EFFECT FOR THE ENTIRE AREA THROUGH 12 PM
CDT ON FRIDAY. THERE IS THE THREAT OF HEAVY RAIN LATE THIS
AFTERNOON AND TONIGHT.

THERE IS A SLIGHT RISK OF NUMEROUS SEVERE THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.

A STRONG CAPPING INVERSION HAS INHIBITED THE DEVELOPMENT OF
STORMS THUS FAR THIS AFTERNOON. HOWEVER RECENT CLEARING IN THE
EXISTING LOW CLOUD COVER AND AN APPROACHING COLD FRONT IS
ALLOWING FOR SLOW DESTABILIZATION OF THE AIRMASS. THE
DESTABILIZATION WILL ALLOW FOR A WINDOW OF RAPID THUNDERSTORM
DEVELOPMENT THROUGH TONIGHT. STORMS THAT DEVELOP HAVE THE
POTENTIAL TO QUICKLY BECOME SEVERE...CAPABLE OF PRODUCING VERY
LARGE HAIL...SEVERE WIND AND HEAVY RAINFALL. ADDITIONALLY THERE
WILL BE A LOW THREAT OF TORNADOES WITH ANY STORMS THAT MAY BECOME
SUPERCELLULAR...PRIMARILY ACROSS NORTH CENTRAL ILLINOIS. THE
STORMS ARE EXPECTED TO DEVELOP FIRST OVER NORTHWEST ILLINOIS AND
SPREAD EAST AT 25 TO 30 MPH. DUE TO THE SEVERE THREAT A SEVERE
THUNDERSTORM WATCH IS IN EFFECT UNTIL 10 PM CDT.

LATER TONIGHT A SECOND ROUND OF THUNDERSTORMS WILL BE POSSIBLE
THAT WILL MOVE EAST OUT OF IOWA. LARGE HAIL...SEVERE WINDS AND
VERY HEAVY RAINFALL WILL BE THE PRIMARY THREATS. RAINFALL AMOUNTS
OF 1 TO 2 INCHES ARE LIKELY...WITH LOCAL AMOUNTS OF 2 TO 3
INCHES POSSIBLE. AMOUNTS OVER 2 INCHES MAY PRODUCE LOCAL
FLOODING.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS AND HEAVY RAIN
FRIDAY THROUGH SUNDAY.

THE FRONT IS EXPECTED TO MOVE JUST NORTH OF THE AREA BY FRIDAY
EVENING ALLOWING FOR A VERY UNSTABLE AIRMASS TO CONTINUE OVER
THE REGION. THE AIRMASS COMBINED WITH A SERIES OF UPPER LEVEL
DISTURBANCES WILL ALLOW FOR THE THREAT OF THUNDERSTORM ACTIVITY
THROUGH SUNDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATE THIS AFTERNOON AND TONIGHT.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE
NWS CHICAGO WEBPAGE: WWW.CRH.NOAA.GOV/LOT (LOWER CASE)

LMZ740>746-766-211100-
WINTHROP HARBOR TO WILMETTE HARBOR-WILMETTE HARBOR TO NORTHERLY
ISLAND-NORTHERLY ISLAND TO CALUMET HARBOR-CALUMET HARBOR TO GARY-
GARY TO BURNS HARBOR-BURNS HARBOR TO MICHIGAN CITY-MICHIGAN CITY
TO NEW BUFFALO-LAKE MICHIGAN-
343 PM CDT THU MAY 20 2004

THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS
AND INDIANA WATERS OF LAKE MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER NORTHERN ILLINOIS LATE
THIS AFTERNOON AND THEN MOVE OVER THE LAKE. ISOLATED SEVERE
STORMS ARE POSSIBLE. FREQUENT LIGHTNING IS ALSO EXPECTED.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THUNDERSTORMS ARE AGAIN POSSIBLE FRIDAY THROUGH SUNDAY. SOME
SEVERE STORMS ARE POSSIBLE ALONG WITH FREQUENT LIGHTNING.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE
NWS CHICAGO WEBPAGE: WWW.CRH.NOAA.GOV/LOT (LOWER CASE)

AEP