[LeArc] Forecast Discussion : MLI@ 11/22/02 3:04:21 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 220916
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
310 AM CST FRI NOV 22 2002

UPPER(AND LOWER) RIDGING TO GET SQUEEZED ACRS THE UPPER MS RVR
VALLEY TODAY...AS NEXT WAVE TAKES SHAPE AND DROPS ACRS NORTHERN
SASK./MANITOBA...BEATING DOWN RIDGE AMPLIFICATION IN THE PROCESS.
THUS NEAR TERM CONCERNS TO BE OF FAIR WX VARIETY...SUCH AS CLOUD
COVER AND TEMPS. FIRST CONCERN OF CLOUD COVER...LOOKING AT
STRATUS FIELD ON 11U-3.9U IR FOG LOOP ROTATING DOWN ACRS THE AREA IN
STEEP CYCLONIC FLOW.  SUBSIDENCE BEHIND ELONGATED VORT TAIL
BLOWING BIG HOLES IN THIS DECK...AND EXPECT CLOUD DECREASE TO
CONTINUE TO BUILD ACRS THE WEST HALF OF THE CWA THIS MORNING. WILL
HAVE TO WALK OUT CLOUDS WITH MORNING WORDING EAST OF THE MS RVR
THOUGH. LACK OF STEEP LLVL LAPSE RATES...ALONG WITH INCOMING RIDGE
AND SUBSIDENCE SHOULD KEEP HOLES FROM FILLING IN WITH CU...FOR MUCH
OF CWA SUNNY/MOSTLY SUNNY THIS AFTERNOON. INCOMING RIDGE CENTER AND
LACK OF MIXING MECHANISM SHOULD KEEP MOST OF CWA IN UPPER
30S...AROUND 40 LOOKING AT CURRENT AND EXTRAPOLATED LLVL THERMAL
PARAMETERS...EVEN WITH SOME INSOLATION. LLVL RETURN FLOW AT SFC NOT
TO COMMENCE TIL AFTER 00Z. ONGOING TEMPS IN CURRENT PACKAGE LOOK
GOOD...AND APPEAR TO TAKE ALL THIS INTO ACCOUNT ALREADY. BEFORE
SOUTHERLY SFC FLOW INCREASES LATER TONIGHT...EXPECT QUICK DIURNAL
DROP OFF THIS EVENING UNDER MOSTLY CLEAR SKIES. SFC TROUGH...TRAILING
SOUTHWARD OFF ONTARIO CYCLONE...WILL SWEEP EAST ACRS IA OVERNIGHT.
INCREASING LLVL SOUTHERLY FLOW AHEAD OF THIS FEATURE...AS WELL AS
INCREASING MID TO HIGH LEVEL CLOUDS FROM MID LVL WAA...SHOULD HELP
TEMPS STEADY OUT AND INCREASE LATE...MUCH LIKE PACKAGE ALREADY
ADVERTISING. NICE POS OMEGA FIELD AND CONVERGENT H85-H5 QG FORCING
SWEEP ACRS THE CWA LATE TONIGHT/EARLY SAT MORNING...PROBABLY ENOUGH
FOR PRECIP GENERATION. BUT WILL BANK ON LACK OF DEEP MOISTURE FOR
MOTION PROCESSES TO PRODUCE MUCH MORE THAN CLOUDS.

EXPECT MIDDAY HIGH AROUND AND JUST BEHIND FROPA...BEFORE CANADIAN
AIR SEEPS DOWN FOR ANOTHER ROUND OF SFC CAA SAT NIGHT. THIS SHOULD
ALLOW FOR MID TO UPPER 40S EARLY SAT AFTERNOON WITH BIT OF COLD AIR
LAG BEHIND TROUGH...BEFORE BOTTOM DROPS OUT SAT NIGHT IN INCREASING
NORTHWEST WIND.

ONGOING PACKAGE LOOKS TO BE HANDLING LATEST THINKING AND WILL MAKE
LITTLE OR MINOR ADJUSTMENTS. NO CHANGES TO LONGER RANGE FOR NOW...
ALTHOUGH SUNDAY DIFFERENCES BETWEEN THE AVN-GFS AND ETA SNOW CHANCES
MAY BECOME INTERESTING.

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

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