Hail and Damaging Winds in Illinois, July 15, 2003

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
650 PM CDT MON JUL 14 2003

REGARDING 00Z TAFS...
18Z MESO ETA VERY SUPPORTIVE OF TIMING AND TRENDS IN PREVIOUS TAF
ISSUANCE SO LITTLE CHANGE TO THOSE TAFS.  MOISTURE CONFINED TO
NARROW BAND AHEAD OF FRONT NOW CROSSING MINNESOTA-NW IOWA-SE
NEBRASKA-KANSAS.  IT DOESNT LOOK LIKE TO DEWPOINTS WILL REACH THE
70S IN OUR CWFA AHEAD OF THE FRONT SO HAVE BACKED OFF FROM TEMPO TO
PROB30 ON THUNDERSTORMS.  SOME LINGERING MOISTURE AND INSTABILITY
AFTER SUNRISE.  IF INDEED THE FRONT DOES NOT COME THROUGH UNTIL
AFTER SUNRISE, THERE MIGHT BE A(NOTHER) CHANCE OF SHOWERS OR
THUNDERSTORMS FOR A FEW HOURS AFTER 12Z. AT THIS POINT, PROBABILITY
LOOKS TO LOW TO MENTION FOR TAFS.  POST FRONTAL WNW WINDS LOOK TO
HAVE POTENTIAL TO GUST NEAR OR A BIT ABOVE 20 KTS WITH GOOD MIXING
TOMORROW AFTERNOON.

KAPLAN

DISCUSSION FOR THE 400 PM ZONES/GRIDS

THE FORECAST OMEGA FOR 700 MB FOR EARLY TUESDAY MORNING
IS A LOT MORE DEFINED ON THIS MORNINGS ETA RUN FOR 06
UTC. THE OMEGA FIELD SPLITS OVER NORTHEAST ILLINOIS BY 12
UTC. THERE IS A JET MAXIMUM MOVING INTO NORTHERN WISCONSIN
AND THE CONVERGENT PART OF THE JET ALOFT PASSES OVER
NORTHERN ILLINOIS. WILL PUT THUNDERSTORMS LIKELY FROM
MIDNIGHT TO 12 UTC. MOST OF THE THUNDERSTORMS WILL OCCUR
AROUND MIDNIGHT AND PROBABLY WILL DIE OUT. BY 18 UTC ANOTHER
NEGATIVE OMEGA FIELD MOVES OVER NORTHEAST ILLINOIS. WILL
LEAVE A CHANCE OF THUNDERSTORMS FOR TUESDAY MORNING. BUT
EXPECT WIDELY SCATTERED THUNDERSTORMS. THE FRONT COMES
THROUGH EARLY IN THE AFTERNOON.

ANOTHER LOW WITH A FRONT MOVES INTO THE GREAT LAKES FRIDAY
THROUGH SATURDAY MORNING. WILL FORECAST A CHANCE OF THUNDERSTORMS
FOR FRIDAY NIGHT AND SATURDAY. DURING THE WEEK WILL LOWER THE
HIGHS A LITTLE AS PER THE MRF MODEL. WITH THE NORTHWEST FLOW AND
A HIGH IT MAY BE A LITTLE COOLER UNTIL THE WINDS COME SOUTH
ON FRIDAY.

.CHI...NONE

WHW

AVIATION DISCUSSION FOR 18Z TAFS

GRADIENT STARTING TO TIGHTEN TODAY AS SSE WINDS INCREASE TO 10-15KTS
THIS PM. EXPECT SOME GUSTS TO 15-20KTS LATE AFTERNOON...THEN
DIMINISH TO 10KTS OR SO AFTER SUNSET. FRONT PUSHING ACROSS NORTHERN
PLAINS PROGGED TO PUSH THRU TERMINALS TOWARD END OF THIS PERIOD OR
JUST AFTER. CURRENT THINKING IS THAT TS WILL FORM OUT AHEAD OF FRONT
ACROSS IA/MN/WI AND THEN PUSH THRU TERMINALS AFTER 08Z OVERNIGHT.
MAY BE ADDITIONAL TS INTO MID TO LATE MORNING BEFORE FROPA. WINDS
TURN WSW BY MORNING.

CMS

ILZ003>006-008-010>014-019-020>023-032-033-039-INZ001-002-010-011-019
-151100-

HAZARDOUS WEATHER OUTLOOK...CORRECTION
NATIONAL WEATHER SERVICE CHICAGO IL
345 PM CDT MON JUL 14 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST
ILLINOIS...NORTHWEST INDIANA...AND THE ADJACENT WATERS OF LAKE
MICHIGAN.

.DAY ONE... TONIGHT

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS AFTER MIDNIGHT ACROSS
THE OUTLOOK REGION.

THUNDERSTORMS WILL FORM AHEAD OF A COLD FRONT THAT WILL MOVE INTO
INTO NORTHWEST ILLINOIS AND CENTRAL WISCONSIN BY TUESDAY MORNING.
THUNDERSTORMS WILL LIKELY MOVE INTO THE ROCKFORD AND DIXON AREAS OF
NORTH CENTRAL ILLINOIS AROUND MIDNIGHT...THEN MOVE TO APPROXIMATELY
A CHICAGO TO WATSEKA LINE DURING THE EARLY MORNING HOURS...AND INTO
NORTHWEST INDIANA AROUND SUNRISE.

THE MAIN THREAT WILL BE LARGE HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN... TUESDAY THROUGH SUNDAY

THUNDERSTORMS WILL LINGER INTO TUESDAY MORNING...ESPECIALLY ACROSS
EASTERN PORTIONS OF THE OUTLOOK AREA. THE NEXT CHANCE OF
THUNDERSTORMS AFTER TUESDAY WILL BE FROM LATE THURSDAY NIGHT THROUGH
SATURDAY MORNING.

FLOODING CONTINUES ON THE IROQUOIS RIVER IN IROQUOIS COUNTY IN
ILLINOIS. SEE THE LATEST FLOOD STATEMENTS FOR FURTHER DETAILS.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS MAY BE NEEDED OVERNIGHT TONIGHT.

&&

           NWS CHICAGO WEBPAGE

    HTTP://WWW.CRH.NOAA.GOV/LOT (LOWER CASE)
OR  HTTP://WEATHER.NOAA.GOV/CHICAGO (LOWER CASE)

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