[LeArc] Forecast Discussion : MLI@ 7/25/02 2:28:49 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 250729
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
228 AM CDT THU JUL 25 2002

06Z SURFACE ANALYSIS DEPICTS A COMPLEX SURFACE PATTERN IN THE 
NORTHERN AND CENTRAL PLAINS WITH A COUPLE OF LOW PRESSURE CENTERS 
SITUATED ALONG A FRONTAL BOUNDARY FROM CO NORTHEAST INTO NORTHWEST 
MN.  AREAS OF CONVECTION OVER WESTERN MN AND THE NE-IA BORDER ARE 
ASSOCIATED WITH SEPARATE SHORT WAVE TROUGHS AND A BROAD AREA OF 
850MB WARM AIR ADVECTION.  A THIRD SHORTWAVE IS SETTING OFF 
CONVECTION OVER THE ARX AND NORTHERN DVN CWAS...WHICH IS WEAKENING 
AS IT PROGRESSES INTO A DRIER MORE STABLE AIR MASS.

MAIN FORECAST CONCERN THIS PERIOD IS THE TIMING OF PRECIPITATION 
WITH THE MULTITUDE OF FRONTAL PASSAGES EXPECTED THE NEXT FIVE DAYS.

MODELS ARE IN FAIR AGREEMENT THROUGH 36HRS ALTHOUGH THE AVN SEEMS TO 
HAVE A PROPENSITY TO OVERDEVELOP A COUPLE OF VORT MAXS PROGGED 
THROUGH THE REGION.  BOTH ETA AND AVN QPFS ARE HAVING A DIFFICULT 
TIME SEPARATING THE THREE DISTINCT AREAS OF CONVECTION OVER THE 
UPPER MIDWEST.  THE MAIN FEATURES IN THIS FORECAST ARE (1) A WEAK 
COLD FRONTAL PASSAGE TODAY AND ASSOCIATED PRECIPITATION.  THE EXTENT 
OF CLOUDS TODAY WILL DICTATE AREAL COVERAGE AND STRENGTH.  AT THIS 
TIME...IT APPEARS DEBRIS CLOUDS WILL LIMIT HEATING AND THUS SEVERE 
POTENTIAL...THOUGH THIS WILL NEED TO BE MONITORED.  (2) THE FRONT 
SAGS THROUGH THE CWA AND STALLS JUST SOUTH OF THE AREA FRIDAY.  
CONVECTION SHOULD REDEVELOP ALONG THE WARM FRONT IN A FAVORED 
DIURNAL MODE FRIDAY NIGHT INTO SATURDAY AS IT LIFTS NORTH THROUGH 
THE CWA.

(3) THE NEXT SYSTEM WILL BRING A COLD FRONT NEAR THE AREA 
SUNDAY...THEN THROUGH THE CWA MONDAY.  THE LONG RANGE MODELS HAVE 
BEEN FAIRLY CONSISTENT WITH THIS FEATURE THE PAST FEW DAYS.  HIGH 
PRESSURE SHOULD BUILD INTO THE AREA BY WEDNESDAY...THUS ONLY CHANGES 
TO THE EXTENDED WILL BE TO DROP POPS THAT DAY.  IF THE FRONTAL 
PASSAGE MONDAY IS FAST ENOUGH...TUESDAY MAY BE DRY TOO.

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

WOLF