[LeArc] Forecast Discussion : MLI@ 9/3/02 2:36:38 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 030742
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
242 AM CDT TUE SEP 3 2002

STRONG MID LEVEL TROUGH OVER SOUTHERN MANITOBA AT 00Z WITH UPPER RIDGE
TO THE WEST AHEAD OF NEXT SYSTEM MOVING INTO BRITISH COLUMBIA.  AT THE
SURFACE AT 06Z COLD FRONT ASSOCIATED WITH MANITOBA SYSTEM WAS JUST EAST
AND SOUTH OF CWA. FRONT STILL HAS A DECENT PUSH WITH 4MB 3HR PRESSURE
RISES OVER NORTHERN IL/SOUTHERN WI.   SURFACE HIGH WAS LOCATED OVER
CENTRAL NE.  AIRMASS NEAR THE HIGH IS COOL AND DRY.  06Z TEMPS JUST
EAST OF THE HIGH WERE IN THE LOWER 50S WITH DEWPOINTS MIDDLE 40 TO
AROUND 50.  CLOSER TO HOME...A POSTFRONTAL BAND OF AC COVER THE
SOUTHEAST HALF OF THE CWA.  ISOLATED ROGUE SHRA CONTINUE TO DEVELOP IN
THE AC BAND.

MODELS IN GENERAL AGREEMENT MOVING MANITOBA TROUGH EAST AND BUILDING
UPPER RIDGE INTO THE MISSISSIPPI VALLEY...AS TROUGH DIGS OVER WEST
COAST.  SURFACE HIGH SETTLES IN TO THE MID/UPPER MISSISSIPPI VALLEY BY
WEDNESDAY MORNING.  MODELS ALL SUGGEST THAT IMPULSE WILL MOVE OVER THE
RIDGE WEDNESDAY NIGHT AND THURSDAY.  AVN THE MOST AGGRESSIVE WITH THIS
FEATURE...BUT IT STILL KEEPS PCPN WEST AND NORTH OF CWA.

MAIN CONCERN IN THIS MORNINGS FORECAST WILL BE TEMPS NEXT COUPLE OF
DAYS AS COOLER AND DRIER AIRMASS SETTLES IN OVER THE REGION.

FOR TODAY...SOME ADJUSTMENTS MAY HAVE TO BE MADE THIS MORNING FOR THE
DEPARTING AC OVER SOUTHEAST CWA.  UNLESS THERE IS A SIGNIFICANT
INCREASE IN SHRA ASSOCIATED WITH THESE CLOUDS...WILL LEAVE FORECAST
DRY AND NOWCAST PCPN IN THE SOUTH.   BELIEVE LIGHT WINDS NEXT FEW
DAYS WILL MAKE IT HARD TO MIX ALL THE WAY TO 850. TEMPS THROUGH
THURSDAY WILL GENERALLY FAVOR THE COOLER MAV NUMBERS.  THE EXCEPTION
WILL BE WEDNESDAY MORNING.  SURFACE HIGH SHOULD BE CENTERED JUST NORTH
OF CWA EARLY WEDNESDAY.  EXPECT DEW POINTS TO BE IN THE MID TO UPPER
40S  WITH CLEAR SKIES AND LIGHT WINDS...WE SHOULD HAVE IDEAL
RADIATIONAL COOLING.  MOS TEMPS SEEM HIGH FOR THESE CONDITIONS.  A
LOOK AT THE ETA BUFR DATA MAY REVEAL THE REASON FOR THIS.  THE BUFR
DATA BY EARLY WEDNESDAY MORNING SHOWS A VERY SHARP/SHALLOW INVERSION IN
EASTERN IA.  MOS MAY NOT BE PICKING UP ON THE INVERSION AND THEREFORE
OVERDOING TEMPS.  CURRENT FORECAST PACKAGE HAS LOW TO MID 50S GOING
AND WILL STICK WITH THESE NUMBERS. PCPN THREAT FOR WEDNESDAY
NIGHT/THURSDAY SHOULD STAY WEST AND NORTH OF CWA...SO WILL CONTINUE
DRY FORECAST.  NO CHANGES PLANNED FOR THE EXTENDED.  LOOKS LIKE QUIET
WX WILL CONTINUE WITH SURFACE RIDGE CONTINUING TO INFLUENCE REGION
EARLY IN THE PERIOD AND UPPER RIDGE BUILDS EAST.

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

DLF