[LeArc] Forecast Discussion : MLI@ 8/9/02 2:01:50 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 090704
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
200 AM CDT FRI AUG 9 2002

00Z UPPER AIR ANALYSIS AND WATER VAPOR IMAGERY SHOW STRONG CLOSED UPPER LOW 
OVER EASTERN MT WITH MID LEVEL TROUGH AXIS EXTENDING THROUGH
NORTHERN AND CENTRAL ROCKIES. THIS COUPLED WITH EASTWARD ADVANCING SURFACE
FRONTAL ZONE OVER NORTHERN PLAINS TRIGGERING SEVERAL
CONVECTIVE CLUSTERS IN THE HIGH PLAINS. CLOSER TO HOME...RIDGING AT THE
SURFACE AND ALOFT DOMINATES FROM MID MISSISSIPPI VALLEY INTO THE GREAT LAKES.

SEVERAL CONCERNS THIS FORECAST CYCLE INCLUDING PCPN POTENTIAL WITH 
FRONTAL PASSAGE SAT AND IMPACT ON TEMPS...THEN PCPN CHCS AND EXTENT OF COOL DOWN
WITH STRONG SYSTEM EARLY NEXT WEEK. 

MODELS AGREE ON BREAKING DOWN UPPER RIDGE NEXT 48 HRS AS STRONG CLOSED 
UPPER LEVEL LOW MOVES FROM EASTERN MT INTO WESTERN GREAT LAKES.
FOR TODAY...COMFORTABLE CONDITIONS ONCE AGAIN WITH SOME INCREASE IN LLVL
MOISTURE WITH DEWPTS IN THE L60S. LLVL WINDS E/SE LIMITING WARM ADVECTION WITH
AIR BEING RECIRCULATED FROM SURFACE HIGH OVER OHIO VALLEY. SO...EXPECT
TEMPS TO BE A FEW DEGS ABOVE THURSDAY/S READINGS WHICH WILL PUT THE RANGE FROM
80 TO 85 MOST OF CWA. TONIGHT...VARIOUS PARAMETERS SUGGEST SCATTERED
CONVECTION MOVING THROUGH WESTERN AND POSSIBLY INTO CENTRAL IOWA LATE AHEAD
OF FRONTAL ZONE. AS CONVECTION PUSHES EAST OF I-35 IT WILL BE 
RUNNING INTO DRIER AIR CONTINUING TO BE FED INTO THE REGION FROM SURFACE HIGH
ON LLVL SE WINDS. META 2M TEMPS LOOK TOO COOL (M50S) EVEN THOUGH LLVL
FLOW WILL BE WEAK...WITH SOME INCREASE IN LLVL MOISTURE AND ALSO HIGH CLOUDS.
THEREFORE...WILL BE SIDING TOWARD BLEND OF AVN/FWC GUIDANCE SUGGESTING
NEAR 60 OR LOWER 60S. ON SAT...MODELS IN DECENT AGREEMENT ON FRONTAL ZONE
MOVING THROUGH IN THE AFTERNOON AND EVENING. SEVERAL NEG FACTORS FOR MUCH PCPN
WITH FRONT INCLUDING LIMITED MOISTURE AND DYNAMICAL FORCING LIFTING NORTH.
STILL...ENOUGH MOISTURE AND FRONTAL CONVERGENCE AND TIMING
OF FRONTAL ZONE TAKING ADVANTAGE OF DIURNAL HEATING SUGGESTS 30-40% MAV POPS
REASONABLE. TEMPS NEXT CONCERN SAT WITH POTENTIAL FOR BUST. 
OVERALL...GIVEN LIMITED MOISTURE BELIEVE ENOUGH SUNSHINE TO FILTER THROUGH
MID/UPPER LEVEL CLOUDS. MCCLURE METHOD SUPPORTS M80S TO NEAR 90 DEGS
NORTH TO SOUTH WITH AMPLE SUNSHINE...AND WILL BANK ON ENOUGH SUNSHINE AND
COMPRESSIONAL HEATING TO REACH.  

THERE ARE HINTS OF THE FRONTAL ZONE PULLING UP TO OUR SOUTH ON SUN AND RETURNING
NORTH QUICKLY SUN NIGHT. LLJ AND THETA-E RIDGE SUPPORTIVE OF ANY PCPN
STAYING TO OUR WEST FROM WESTERN MN SOUTH THROUGH CENTRAL/WESTERN IA AND EASTERN
NE...BUT THIS BEARS SOME WATCHING.  

EXTENDED (MON-THU)...NO MAJOR CHANGES EXPECTED AS CURRENT FORECAST LOOKS TO
BE ON TRACK WITH STRONG UPPER TROUGH AND SURFACE FRONT BRINGING
DECENT SHOT OF PCPN ESPECIALLY LATE MON THROUGH EARLY TUE...FOLLOWED BY NICE
COOL DOWN WITH CANADIAN HIGH BUILDING IN. UPPER PATTERN SUGGESTIVE
OF COOL CONDITIONS PERSISTING FOR SEVERAL MORE DAYS BEYOND SCOPE OF CURRENT 
EXTENDED. 

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


05