[LeArc] Forecast Discussion : MLI@ 5/23/02 2:34:56 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 230734
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
235 AM THU MAY 23 2002

UPPER SYSTEM DRIVING LATE SEASON SNOW STORM OVER THE NORTHERN ROCKIES
PROGGED TO LIFT NE TODAY.  ANOTHER POTENT TROUGH JUST MOVING INTO THE
INTERMOUNTAIN REGION AT 00Z.  COLD FRONT ASSOCIATED WITH NORTHERN
PLAINS SYSTEM EXTENDS FROM WRN MN THRU NORTHEAST NE INTO NW KS AT 06Z.
CONVECTION THAT DEVELOPED AHEAD OF THE FRONT WED EVE MOVING THROUGH
S CENTRAL IA ATM AND IS WEAKENING WITH TIME.  ANOTHER LINE OF ELEVATED
SHRA POPPED ON LEADING EDGE OF MID CLOUD DECK WITH IN THE LAST HOUR OVER
EASTERN CWA. HOWEVER...RADAR LOOP SHOWS SHRA WEAKENING AS THEY MOVE
EAST.

MODELS HANDLE UA FEATURES SIMILARLY NEXT 48 HRS MOVING NORTHERN PLAINS
SYSTEM EAST...FLATTENING OUT RIDGE OVER EASTERN U.S. NV/CA S/W MOVES
EAST INTO MISSISSIPPI VALLEY BY 12Z SAT.  SURFACE FRONT MOVES SE AND
STALLS OVER NORHTERN HALF OF MO BY 12Z FRI.  SURFACE WAVE DEVELOPS
ALONG FRONT AND MOVES NORTHEAST THROUGH SOUTHERN CWA FRI NIGHT. AVN
APPEARS TO HAVE INITIALIZED A LITTE BETTER ON THE WRN U.S. S/W
CAPTURING THE H300 JET MOVING INTO BASE OF TROUGH BETTER THAN THE ETA.
AVN HAS BEEN CONSISTENT STALLING THE FRONT OUT FURTHER N THAN ETA LAST
COUPLE OF RUNS...SO WILL STICK WITH AVN SOLN.

MAIN CONCERNS WILL BE AFTERNOON CONVECTION AND RAINFALL POTENTIAL
WITH SURFACE WAVE FRIDAY NIGHT.  CONVECTION OVER CENTRAL IA IS
DIMINISHING AS IT MOVES EAST.  HOWEVER...AS 850 WINDS VEER EARLY THIS
MORNING...SWLY FLOW SHOULD PROVIDE SOME THETA-E ADVECTION TO SUPPORT
SOME SHRA OVER CENTRAL AND SOUTHERN SECTIONS.  EXPECT TSRA TO FIRE
ALONG FRONT EARLY THIS AFTERNOON AS IT MOVES THROUGH CENTRAL IA.
BEST MOISTURE AND INSTABILITY WILL BE ACROSS THE SOUTH.  BELIEVE
SEVERE THREAT IS BORDERLINE.  LOW LEVEL MOISTURE/CAPE WILL BE MARGINAL
WITH LOW 60 DEWPOINTS AND CAPES AROUND 1000 J/KG.  AVN MOVES IMPRESSIVE
QPF BULLSEYE ACROSS NRN MO TONIGHT...BUT LOOKS OVERDONE DUE TO FEEBACK
ISSUES...ETA IS CONSIDERABLY WEAKER WITH THIS FEATURE. MAIN QPF EVENT
WILL BE FRI NIGHT AS WRN U.S. TROUGH INTERACT WITH STALLED FRONT...
SENDING A SURFACE NE ALONG THE BOUNDARY.  AVN HAS BEEN CONSISTENT WITH
THIS FEATURE SO WILL...BEEF...UP POPS SOUTH TO CATEGORICAL AND GO
LIKELY NORTH.  WITH SURFACE WAVE MOVING THROUGH FAR SOUTH AND PW'S
OVER AN INCH...FEEL THERE IS SOME POTENTIAL FOR HEAVY RAIN ALTHOUGH
MODELS DON'T SEEM TO GENERATE MUCH.  WILL MENTION HEAVY RAIN THREAT
SOUTH...WHERE SOILS ARE STILL RECOVERING FROM LAST WEEKS HEAVY RAINS.

TEMPS IN CURRENT FORECAST LOOK REASONABLE WITH HIGHS TODAY A FEW
DEGREES WARMER THAN MOS DUE WITH APPROACHING FRONT.  WILL BACK OFF
TEMPS SOME FOR FRIDAY WITH EASTERLY FLOW DEVELOPING NORTH OF THE
BOUNDARY BRINGING SOME COOLER AIR OF LM.

THANKS TO ILX FOR COORDINATION.

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

DLF