[LeArc] Forecast Discussion : MLI@ 7/26/2003 5:05:18 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 261001
AFDMLI

AREA FORECAST DISCUSSION...RETRANSMISSION...
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
400 AM CDT SAT JUL 26 2003

PLAN VIEW PROFILERS INDICATING 50 KT SOUTHWEST H85 FLOW CONVERGING
INTO THE LEE OF FRONTAL BOUNDARY HAS SET OFF ELEVATED CONVECTION
FINALLY OVER THE PAST HOUR IN SOUTHERN MN. H7-H3 MB THICKNESS
PATTERNS SUGGEST SOME OF THIS ACTIVITY COULD GET ROUTED TO THE
SOUTHEAST AND POSSIBLY AFFECT THE AREA LATER THIS MORNING...AND
THUS "CHICKENED OUT" ON THE FLY AND WENT 30 POPS FOR THE NORTHERN CWA
FOR ENTIRE DAY. BUT...LIKE 06Z META AND LATEST UKMET SUGGEST...
ACTIVITY WILL EITHER CONTINUE EAST AND STAY NORTH OF THE CWA...OR
IF IT TRIES AND SPILL SOUTHEAST GET ERODED BY STRONG CAP OR DECAY AS
IT TRAVELS AWAY FROM H85-H7 CONVERGENCE THAT SPAWNED IT. THUS
ORIGINAL PLAN OF A VERY WARM AND INCREASINGLY HUMID DAY TO BE ON TAP
WITH NO PRECIP STILL PROBABLY TO PAN OUT. JUST SOME ELEVATED
CONVECTIVE DEBRIS CLOUDS TO CONTEND WITH.  MIXING HEIGHTS TO BE
LIMITED BY WARM WEDGE ALOFT...AND THUS FULL THERMAL POTENTIAL NOT
TO BE REALIZED(COULD BE IN THE UPPER 90S). STILL TEMPS TO CLIMB INTO
THE UPPER 80S TO LOWER 90S...WITH SFC DPT INCREASING INTO THE 70S BY
THIS AFTERNOON. THUS HAVE ADDED SOME HEAT INDICES APPROACHING THE
100 DEGREE MARK WORDING IN ZONES WHERE APPROPRIATE.

LARGE UPPER RIDGE TO CONTINUE TO DOMINATE THE MID MS RVR VALLEY
TODAY...WITH MAIN WESTERLY STORM TRACK TO CONTINUE FROM THE
DAKOTAS...THROUGH MN AND WI.  AS WAVE ENERGY OUT OF CANADA DIGS
OUT TROUGH OVER THE NORTHERN GRT LKS BY LATE TONIGHT...INCREASING
NORTHWEST CYCLONIC FLOW TO GET SHUNTED TO THE SOUTHWEST OF THE GRT
LKS AND OVER THE LOCAL AREA BY SUNDAY MORNING. WELL ADVERTISED
FRONT ALIGNED IN A NORTHEAST-TO-SOUTHWEST FASHION NOW LAYING OUT
ACRS THE NORTHERN PLAINS AND MN...WILL FINALLY GET PUSHED INTO THE
CWA AS THIS OCCURS. BEFORE THEN...H8-H7 MB CAP WILL GET REINFORCED
TODAY BY WEST-SOUTHWEST FLOW AT THAT LAYER TAPPING INTO WARM THERMAL
DOME ACRS THE WESTERN PLAINS. THUS CONVECTION MAY BE LIMITED TO
FORCING JUST AHEAD OF THE FRONT AND AGAIN THAT MAY NOT OCCUR TO LATER
TONIGHT. LATEST SHORT RANGE MODELS GENERALLY SUGGEST BOUNDARY TO
ECLIPSE THE NORTHWEST THIRD OF THE CWA BY AROUND 09Z SUN...BUT WILL
EXPECT SOME PREFRONTAL PRECIP BEFORE THEN. AGREE WITH CHI(LOT) THAT
LATER PRECIP HOLDS OFF TONIGHT...LESS CHANCE OF A SEVERE POTENTIAL.
IF CONVECTION WERE TO SOMEHOW IGNITE THIS AFTERNOON(UNEXPECTED CAP
WEAKENING FROM THE NORTH THAT EARLY THOUGH)...AMOUNT OF PENT UP CAPE
AND PROGGED BOUNDARY LAYER ENERGY POTENTIAL COULD CREATE STORMS THAT
WOULD EVOLVE INTO 70 MPH STRAIGHT LINE WIND PRODUCERS.

AS DEEPENING SFC LOW PUSHES EAST ACRS THE LAKES...FRONTAL BOUNDARY
AND LLVL BAROCLINICTY TO GET LAID OUT FROM EAST-TO-WEST ACRS THE
SOUTHERN THIRD OF THE CWA ON SUNDAY. WILL FAVOR LATEST UKMET AND ITS
FURTHER NORTH "HANG UP" POSITION TAKING INTO ACCOUNT STRENGTH OF
CENTRAL PLAINS AND CENTRAL MS RVR VALLEY MID LEVEL RIDGE. THIS
BOUNDARY POSITION THINKING AND WITH INCREASING CYCLONIC AND NORTHWEST
FLOW ALOFT...AS WELL AS IMPINGING SOUTHERN EDGE OF H25 JET MAX
GRADIENT...SUNDAY MAY BE THE DAY MOST OF THE CWA EXPERIENCES
THUNDERSTORM ACTIVITY. HAVE TONED DOWN SUNDAY TEMPS A CATEGORY DUE TO
EXPECTED CONVECTION AND INCREASED AREAL COVERAGE. WITH FCST SOUNDINGS
INDICATING PW'S ON SUNDAY AROUND 2 INCHES...ANY CONVECTIVE COMPLEXES
ALONG THE BOUNDARY SHOULD PRODUCE SOME LOCALLY HEAVY RAINFALL. AGAIN
LATEST INDICATIONS SUGGEST THE BEST CHANCE OF THIS OCCURRING IS ACRS
CENTRAL TO SOUTHERN THIRD OF THE CWA. UKMET FRONTAL BOUNDARY POSITION
WOULD FAVOR HEAVY RAIN SWATH EXTENDING ALONG AND JUST SOUTH OF THE
INTERSTATE 80 CORRIDOR. ONGOING PACKAGE GENERALLY HANDLING OVERALL
TRENDS WELL STILL AND ONLY MADE MINOR ADJUSTMENTS THROUGH SUNDAY
NIGHT.


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

$$

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