[LeArc] Forecast Discussion : MLI@ 6/12/2003 3:48:05 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 122033
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
333 PM CDT THU JUN 12 2003

STRATUS HAS BEEN SLOW TO CLEAR TODAY...WITH STILL NO SIGN OF 
SUNSHINE AT 20Z AT DVN. THIS...ALONG WITH CONSIDERABLE CI FROM 
NUMEROUS UPSTREAM TSRA COMPLEXES HOLDING TEMPERATURES IN 70S.
MOST SIGNIFICANT SHORT TERM FEATURE IS VERY SLOW MOVING TSRA COMPLEX 
FROM SE NEB INTO NW MO AND SW IA THAT HAS NOT MOVED MUCH OVER PAST 6 
HOURS. THIS COMPLEX WAS ASSOCIATED WITH VERY SLOW MOVING H5 VORT MAX 
OVER NE KS AND LOW LEVEL CONVERGENCE OF SURFACE TROUGH FROM WESTERN 
MN INTO SE NEB AND STATIONARY FRONT FROM INDIANA TO NORTHEAST KS. 

SHORT TERM MODELS TAKE THIS FEATURE E-SE ACROSS NORTH CENTRAL MO 
TONIGHT WITH MAIN FORCING TO ITS NORTHEAST IMPACTING MAINLY 
SOUTHWEST CWFA. ETA HAS SYSTEM BECOMING OPEN WAVE AND PASSING OVER 
FORECAST AREA...BUT BASED ON CURRENT TRENDS...GFS SOLUTION WITH MORE 
CLOSED CIRCULATION STAYING TO SOUTH PREFERRED. THUS KEPT CHANCE POPS 
ACROSS SOUTH TONIGHT WITH PROXIMITY OF TSRA COMPLEX KEEPING CI THIN 
OVERCAST. A FEW BRIEF SHRA/TSRA OCCURRED EARLIER THIS AFTERNOON IN 
NORTH CENTRAL IA ALONG EDGE OF WESTERN IA SURFACE THETA E RIDGE 
AXIS. THIS SLOW MOVING TROUGH PUSHES THROUGH AREA ON FRIDAY...BUT IS 
EXPECTED TO WEAKEN CONSIDERABLY AND NOT HAVE AS MUCH UPPER LEVEL 
SUPPORT SO WILL LEAVE OUT POPS AT THIS TIME...BUT KEEP FAR SOUTHEAST 
IN TSRA CHANCES FOR LINGERING CONVECTION IN PROXIMITY OF SLOWLY 
MOVING VORT TO SOUTH. 

HAVE REMOVED POPS FROM WEEKEND AS SURFACE HIGH PASSES TO NORTH AND 
STALLED FRONT TO SOUTH PUSHES FURTHER SOUTH AND KEEPS US OUT OF 
TYPICAL JUNE HUMIDITY. RESULTANT REDEVELOPMENT OF LOW LEVEL NE-E 
FLOW WILL KEEP TEMPERATURES NEAR TO JUST BELOW AVERAGE WITH 
NIGHTTIME STRATUS HOPEFULLY LESS OF A PROBLEM AS SURFACE LOW OVER 
OHIO VALLEY PUSHES EASTWARD AND AIRMASS IN GREAT LAKES TRAJECTORY 
DRIES SOME. THIS TREND WILL NEED TO BE MONITORED...AS CLOUDS WOULD 
HAVE BIG IMPACT ON TEMPERATURES...MUCH LIKE WE HAVE SEEN THIS 
WEEK.   

EXTENDED...MONDAY THROUGH THURSDAY...
PROGRESSIVE UPPER LEVEL FLOW KEEPS SYSTEMS EMBEDDED IN WESTERLY FLOW 
MAINLY NORTH OF US/CAN BORDER. MEDIUM RANGE GUIDANCE SHOWS 
BROAD...SLOW MOVING UPPER VORTEX SHOWN TO DEVELOP OVER WEEKEND AND 
SPIN SLOWLY THROUGH MID WEEK IN WEAK FLOW ACROSS MID MISSISSIPPI 
VALLEY OR SOUTHERN PLAINS...DEPENDING ON THE MODEL. THIS PLACES 
FORECAST AREA UNDER WEAK ZONAL RIDGE AT SURFACE WITH EASTERLY FLOW 
AND DRY WEATHER THROUGH TUESDAY. NOT MUCH CONSENSUS TOWARD THURSDAY 
AND FRIDAY...BUT BOTH ECMWF AND GFS INDICATE A STRONG CANADIAN UPPER 
LEVEL TROUGH TO IMPACT AREA WITH SURFACE FRONTAL PASSAGE LATE WED 
INTO EARLY THURSDAY AND HAVE INTRODUCED TSRA CHANCES. TEMPERATURES 
SHOULD CONTINUE BELOW CLIMO...ESPECIALLY WITH LOWS IN SUCH 
PATTERN...AND WENT CLOSE OR JUST BELOW GFS MOS GUIDANCE.   

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

SHEETS
$$