[LeArc] Forecast Discussion : MLI@ 7/16/02 2:39:38 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 161939
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
235 PM CDT TUE JUL 16 2002

BROAD UPPER RIDGE IN PLACE OVER CENTRAL U.S. REMANANTS OF OLD
UPPER LOW OVER SOUTH CENTRAL U.S. STILL IDENTIFIABLE AS A SHEAR
AXIS FROM OK THRU SOUTHERN MO/IL.  AT THE SURFACE...HIGH PRESSURE
THAT BROUGHT THE...PLEASANT...SUMMER WEATHER TO THE REGION LAST SEVERAL
DAYS WAS NOW CENTERED OVER CENTRAL IL/IN.  SOUTHERLY FLOW WEST OF HI
WAS RETURNING HIER DEWPOINT AIR TO THE REGION.

IN THE NEAR TERM SIMILAR HANDLING U/A AND SURFACE FEATURES.
SHEAR AXIS LIFTS INTO NORTHERN MO BY EARLY WEDNESDAY. AS UPPER RIDGE
SHARPENS OVER ROCKIES...SHEAR AXIS GETS CAUGHT UP IN INCREASING
NORTHWEST FLOW AND MOVES SOUTHEAST LATE WEDNESDAY.  MODELS SHOW
DIFFERENCES HANDLING SURFACE FRONT MOVING THROUGH THURSDAY NIGHT.  ETA
SHOWING MORE OF A BACKDOOR FRONT DUE TO ITS STRONGER SURFACE HIGH OVER
NORTHERN GREAT LAKES. AVN WEAKER WITH AND E/W ORIENTED BOUNDARY.  ETA
APPEARS TO BE VERIFYING BETTER WITH SURFACE HIGH OVER CENTRAL CANADA
THIS AFTERNOON...SO WILL LEAN TOWARD ETA SOLUTION FOR THURSDAY/THURSDAY
NIGHT.

MAIN SHORT TERM CONCERN WILL BE IMPACT OF SHEAR AXIS TO THE SOUTH
THROUGH WEDNESDAY AND THEN SURFACE FRONT LATE THURSDAY.  MOST
CONVECTION YESTERDAY AND THIS AFTERNOON...SO FAR...IS OCCURING
ALONG AND SOUTH OF SHEAR AXIS.  MODELS KEEP SHEAR AXIS JUST SOUTH OF CWA
BY THURSDAY AFTERNOON...SO WILL ONLY GO WITH LOW POPS SOUTH AND REMOVE
POPS REST OF CWA.  WILL KEEP THURSDAY DRY FOR NOW...WITH BOTH ETA/AVN
INIDICATING PCPN THREAT TO BE NORTH OF CWA BY EVENING.  AS BOUNDARY
MOVES THROUGH OVERNIGHT...WILL CONTINUE CHANCE POPS MOST AREAS.  THINGS
BECOME MORE UNCERTAIN FRIDAY WITH POSITION OF SURFACE FRONT WITH AVN
PUSHING FRONT WELL SOUTH OF REGION...WHILE 84HR ETA INDICATES FRONT
STALLS JUST SOUTH OF CWA.  WILL CONTINUE CHANCE POPS CENTRAL AND SOUTH
FRIDAY...BASED ON MORE CLIMATOLOGICAL CORRECT SLOWER MOVEMENT...BUT
LATER SHIFTS WILL HAVE TO RE-VALUATE.

NEAR TERM TEMPS WILL FAVOR MAV TEMPS FOR THE  MOST PART.  THURSDAY
SHOULD BE THE MOST OPPRESSIVE DAY WITH TEMPS AROUND 90 AND UPPER 60
AND LOWER 70 DEWPOINTS POOLING AHEAD OF FRONT.



.EXTENDED (SAT THRU TUES)
12Z AVN/UKMET SIMILAR HANDLING U/A FEATURES...WHICH ARE WEAKER THAN
00Z MRF...SO WILL LEAN TOWARD 12Z AVN AND GO WITH DRY FORECAST FOR THE
WEEKEND WITH DRY EASTERLY LOW LEVEL FLOW OVER REGION.   EARLY NEXT WEEK
MODELS MOVE ANOTHER FRONT INTO THE PLAINS...WITH MRF MOVING IT THROUGH
THE REGION BY TUESDAY. AGAIN MRF MOST AGGRESSIVE BY MONDAY MORNING.  FOR
NOW WILL GO WITH CHANCE WORDING MONDAY AND TUESDAY.



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

DLF