Damaging Wind in Illinois, August 5, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
145 PM CDT MON AUG 5 2002

MODELS DIFFER WITH HANDLING MCS TONIGHT/TUE MOVING SE FROM IA ACROSS
NE MO INTO SW IL. ETA MOST AGGRESSIVE WITH QPF FURTHER NE INTO CENTRAL
IL...WHILE AVN DRIEST AND NGM IN BETWEEN. MCS PARAMETERS LIKE THE
850-925 TEMP/MOISTURE ADVECTION NOT SUPPORTING HEAVY QPF THIS FAR
NE AS ETA IS SHOWING AND WILL LEAN MORE TOWARD THE NGM/AVN. FORECAST
CHALLENGE IS ADDRESSING CONVECTION CHANCES INTO EARLY TUE. ALSO HOW
MUCH COOLER AND LESS HUMID IT WILL BE DURING MID WEEK...AS CANADIAN
HIGH PRESSURE DRIFTS SE INTO THE GREAT LAKES.

18Z SURFACE ANALYSIS HAS LEADING EDGE OF FRONTAL BOUNDARY JUST SOUTH
OF I-70 FROM KSTL TO KHUF. TROPICAL AIR MASS LINGERS WELL BEHIND THE
FRONT WITH DEWPOINTS IN THE 70S NORTH INTO SOUTHERN WI/MI. TEMPS
RANGE FROM THE MID 80S N TO NEAR 95 S OF I-70 WHERE HEAT INDICES AT
105. PARTLY TO MOSTLY SUNNY WITH ISOLATED CONVECTION NE AND SW OF
CWA. LETTING HEAT ADVISORY SOUTH OF I-70 EXPIRE AT 4 PM WITH NEW ZFP.

FRONTAL BOUNDARY SLIPS SOUTH OF KLWV LATE THIS AFTERNOON WHILE MCS
DEVELOPS OVER SOUTHCENTRAL IA THIS EVENING AND MOVES SE ACROSS SW IL
OVERNIGHT INTO EARLY TUE MORNING. RECONFIGURED ZONES INTO 3 GROUPS
WITH SW GROUP FROM GALESBURG TO KSPI WSW HAVING GOOD CHANCE TONIGHT
AND PROB30 EARLY TUE MORNING WHILE REST OF CWA HAS PROB30 JUST THIS
EVENING AS DRIER AIR MOVES IN FROM THE NE. LOWS TONIGHT IN MID TO
UPPER 60S WITH COOLEST READINGS NE GROUP. DEWPOINTS SLIP INTO THE
UPPER 50S AND LOWER 60S TUE AFTERNOON AND 50S WED AS CANADIAN HIGH
DRIFTS SE ACROSS THE WESTERN GREAT LAKES. MORE COMFORTABLE TEMPS
WITH LOWS 55 TO 60 AND HIGHS 80 TO 85...COOLEST READINGS NE BY I-74.

HIGH PRESSURE DRIFTS EAST BY FRI WITH RETURN SOUTH FLOW DEVELOPING.
MRF IS STILL MOST AGGRESSIVE MODEL WITH UPPER LEVEL TROUGH FROM THE
PACIFIC NW MOVING EAST INTO THE MIDWEST THIS WEEKEND. WILL MAINTAIN
CHANCE OF CONVECTION THIS WEEKEND AND CONTINUE DAY 7/MON. DID NOTICE
THAT NOGAPS AND ECMWF SLOWER WITH THIS TROUGH AND STRONGER WITH
UPPER LEVEL RIDGE IN NATIONS MID SECTION AND LOOK DRY UNTIL SAT
NIGHT. MODELS BACK OFF ON WARMING LATE THIS WEEK AS 850 TEMPS THAT
SLIP TO 14C DURING MIDWEEK REBOUND A FEW DEGREES BY THE WEEKEND...
NOT TO AROUND 20C THAT WE HAVE HAD WITH THE RECENT HEAT WAVE.

SPI BU 067/083 058/082 058 07530
PIA AU 065/081 057/080 057 07310
DEC AU 065/082 058/082 057 07310
CMI AU 064/081 056/080 056 07300
MTO BU 066/084 058/082 058 07310
LWV BU 069/086 060/084 059 07310

.ILX...NONE.

GEELHART/HUETTL