Severe Thunderstorm Warning 70, NWS Chicago, IL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
300 PM CDT TUE OCT 23 2001

MAIN WX EVENT WILL BE FROPA ON WED...USHERING IN MUCH COOLER AND
WINDY CONDITIONS.

CURRENT SHRA AND TSRA FROM SOUTHEAST MO ACROSS SOUTHERN QUARTER OF
IL AND SOUTH HALF OF IND TO REMAIN SOUTH OF CWFA THIS EVENING...AND
ENDING FROM W TO E AS A SHORT WAVE TROUGH MOVES ENE FROM THE OZARKS
INTO THE LOWER OH VALLEY AND THE RIGHT ENTRANCE REGION OF JET MAX
ALSO MOVE ENE...AND INTO THE UPPER OH VALLEY BY 06Z.

THERE IS A CHANCE OF SHRA AND TSRA DEVELOPMENT FURTHER NORTH IN
NORTHERN IL AND SOUTHERN WI THIS EVENING AS LOW LEVEL FLOW INCREASES
ACROSS SFC BOUNDARY FROM SOUTHERN LOWER MI INTO FAR NORTHERN MO
AHEAD OF THE DEEPENING UPPER LOW OVER THE NORTHERN PLAINS TONIGHT.
WARM FRONT TO LIFT N OF CWFA BY 06Z WITH ASSOCIATED THREAT OF
CONVECTION ALSO SHIFTING NE BY THEN.

COLD FRONT CURRENTLY IN NORTHERN HIGH PLAINS TO MOVE RAPIDLY E
TONIGHT AND INTO SW WI AND NW IL BY 12Z THU AS SYSTEM DEEPENS.
SQUALL LINE DEVELOPMENT EXPECTED TONIGHT WITH GOOD LOW LEVEL
CONVERGENCE IN UNSTABLE AIRMASS. CDFNT MOVES THROUGH NE AND E CNTRL
IL BY MIDDAY WED ENDING ANY SIGNIFICANT PRECIP...WITH GOOD CAA
ADVECTION AND SUBSIDENCE OVERSPREADING AREA. REINFORCING SHOT OF CAA
WED NIGHT WITH SECONDARY CFP AS UPPER LOW CONTINUES TO DEEPEN AND
LIFT NE FROM THE WESTERN LAKES INTO ONTARIO.

WRAP AROUND MOISTURE PERSISTS ACROSS NORTHERN IL WED NIGHT AND THU
BUT ISENTROPICS SHOW CONTINUED DOWNGLIDE...LIMITING PRECIP THREAT TO
A FEW NUISANCE SPITS/FLURRIES.

WITH HIGHER DEW POINTS CONTINUING TO SPREAD N INTO NORTHERN
IL...OVERNIGHT LOWS NOT TO FALL MUCH FROM CURRENT READINGS...WITH
HIGHS WED TO BE MORNING/EARLY AFTERNOON BEFORE CFP.

COOL CONDITIONS TO PERSIST UNTIL LATE WEEKEND WHEN UPPER RIDGING
WORKS EAST ACROSS THE PLAINS ALLOWING MODERATION OF TEMPS.

.CHI...NONE.

TRS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
1120 PM CDT TUE OCT 23 2001

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

1110 PM    LAKE SUMMERSET                 IL   QUARTER SIZE HAIL
10/23/01   WINNEBAGO