[LeArc] Forecast Discussion : MLI@ 6/10/02 2:39:32 PM

[learc@mailman.qth.net]

The following weather message is provided by McDonough County E.S.D.A.


FXUS63 KDVN 101939
AFDMLI

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