Damaging Winds in Illinois, June 10, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
239 PM CDT MON JUN 10 2002

FORECAST CHALLENGE CONTINUES TO CENTER ON SHOWERS AND THUNDERSTORMS
OVER NEXT 48 HOURS. AT 18Z...SURFACE ANALYSIS SHOWED LOW PRESSURE
CENTER OVER SE ND WITH COLD FRONT TRAILING S-SE INTO SE CO. AT UPPER
LEVELS...RIDGE DOMINATED SE CONUS WITH STRONG LOW OVER NRN ROCKIES.
RESULTING DEEP SOUTHERLY FLOW HAS PROVIDED VERY MOIST AIRMASS ACROSS
CWFA WITH MIDDAY DEWPOINTS INTO 70S AT SURFACE...AND 12Z SOUNDINGS
SHOWING H85 READINGS ABOVE 14 C...AND PRECIPITABLE WATER 1.8 AT DVN.
THUNDERSTORMS THIS MORNING MAINLY ASSOCIATED WITH H5 WAVE PASSING TO
NORTH WITH WEAK OMEGA LOBE TRAILING S ACROSS WRN IL INTO NE MO
CONTINUING TO FIRE TSRA EARLY THIS AFTERNOON.

MODELS INITIALIZED WELL AND WERE NOT TOO FAR APART IN NEAR TERM WITH
HANDLING OF MAIN UPPER FEATURES. AVN HAD BEST HANDLE ON QPF COVERAGE
AT 18Z...WITH OTHER MODELS TOO FAR BACK INTO CENTRAL AND EASTERN IA.
AVN WAS ALSO PREFERED IN SHORT TERM WITH LOCATION OF WEAK H5
SHORTWAVES. HOWEVER...AVN QPF WAY OVERDONE OVER NW CWFA THIS
AFTERNOON AND THUS BLEND OF AVN AND ETA USED FOR FIRST FEW PERIODS.
BEYOND...AVN IS STRONGER AND SLOWER WITH UPPER LOW ALONG US/CAN
BORDER. AT SURFACE...COLD FRONT PASSES THROUGH ON TUESDAY WITH AVN
CONTINUING ITS PROGRESS SOUTH WHILE ETA HANGS IT UP OVER SE IA. WILL
GO ALONG WITH COMPROMISE FRONTAL POSITION FOR WEDNESDAY AND KEEP
POPS GOING IN THE SOUTH.

WITH CONVECTION CURRENTLY STARTING TO FIRE IN EASTERN IA AT EDGE OF
AREA THAT HAS HAD MOST SUNSHINE TODAY...WILL HAVE TO WAIT UNTIL LAST
MINUTE FOR AREAL COVERAGE THIS EVENING IN IA WITH SCATTERED COVERAGE
EXPECTED IN EVENING IN IL AND MO. MAIN OVERNIGHT FORCING WILL BE
WEAK H7 WAVE SEEN ON WATER VAPOR IMAGERY MOVING INTO SE NEB. THIS
SHOULD BE MAIN TRIGGER FOR TSRA OVER MAINLY NORTHWEST ZONES WELL
AFTER SUNSET. FOCUS ON TUESDAY WILL BE CONVERGENCE ALONG FRONT IN
AFTERNOON. GUIDANCE SCATTERED POPS LOOK TOO LOW AND WILL RAISE TO
LIKELY. WHERE FRONT STALLS OUT TUESDAY NIGHT AND WEDNESDAY WILL BE
CRITICAL AS MID LEVEL FLOW BECOMES PARALLEL TO FRONT WITH FAVORABLE
MOISTURE POOLING TO SET UP HEAVY RAINFALL POTENTIAL. TOO MUCH
UNCERTAINTY FOR MENTION IN ZONES NOW...BUT WILL CONTINUE TO MENTION
IN SIG WX OUTLOOK AND HAVE TO BE MONITORED BY MID SHIFT FOR POSSIBLE
HYDROLOGIC OUTLOOK ISSUANCE. WILL CONTINUE LIKELY POPS FOR TUESDAY
NIGHT AND THEN TRIM CHANCE POPS TO SOUTH FOR WEDNESDAY. AVN PLACES
QPF ACROSS AREA THURSDAY WITH H5 LOW PASSING JUST TO NORTH. UKMO AND
ECMWF HOLD IT BACK FURTHER NORTH AND WILL LEAVE DRY WORDING FOR NOW.

EXTENDED...NOT MUCH AGREEMENT IN MEDIUM RANGE GUIDANCE WITH UPPER
LOW AND LONG WAVE TROUGH MOVING OUT OF GREAT LAKES. MRF IS MOST
PROGRESSIVE...WITH H5 LOW IN SE ONTARIO...WHILE UK AS FAR WEST AS
MSP. WITH UPPER TROUGH OR H5 CYCLONIC CIRCULATION PASSING THROUGH ON
FRIDAY...AFTERNOON SHOWERS CANNOT BE RULED OUT AND HAVE INTRODUCED
CHANCE POPS. NW FLOW OVER WEEKEND WITH MRF INDICATING SHOWERS WITH
EMBEDDED SHORTWAVE AND WEAK SURFACE FRONT. WILL LEAVE DRY FOR
NOW...BUT INTRODUCE POPS FOR MONDAY AS RETURN FLOW SETS UP WITH HIGH
PLAINS LOW AND FRONTOGENESIS ALONG IA/MN BORDER.

.DVN...
IA...NONE.
IL...NONE.
MO...NONE.

DLS