[LeArc] Forecast Discussion : MLI@ 11/9/02 2:55:56 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 092106
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
300 PM CST SAT NOV 9 2002

LATEST SFC AND MSAS ANALYSIS INDICATING RATHER COMPLEX WAVE/TROUGH
SYSTEM OVER THE PLAINS...WITH WIDESPREAD PRESSURE FALLS TO THE EAST
OF IT FROM MN...TO MO. WILL LEAN TOWARD ETA'S PROGRESSION AND
EVOLVEMENT OF THIS SYSTEM TO THE EAST OVERNIGHT...WITH TRAILING SFC
TROUGH PASSING OVER THE MS RVR JUST BEFORE 12Z SUN. CLOUD COVER AND
SOUTH WINDS AHEAD OF THIS TROUGH...AS WELL AS FRESHLY ADVECTED DPTS
IN THE 50S...SHOULD KEEP LOWS UP OVERNIGHT IN REALM OF THE FWC
VALUES. MAIN QUESTION OF FORECAST IS PRECIP OVERNIGHT. BEST LLVL
JET AND MOISTURE FEED...COMBINING WITH CENTRAL PLAINS VORT/FORCING
FROM THE WEST...SHOULD MAKE FOR A BETTER PRECIP MACHINE JUST TO THE
EAST AND SOUTHEAST OF THE CWA OVERNIGHT. DEEP MOISTURE WILL
CONTINUE TO BE A PROBLEM FURTHER TO THE WEST-NORTHWEST OVER THE
LOCAL AREA...BUT ENOUGH OF THE INCOMING PROCESSES TO WARRANT
CHANCE/SCTRD WORDING FOR SHOWERS AND SPRINKLES...WITH HIGHER POPS
ACRS THE EAST. AVN VORT SCENARIO POLLUTED BY FEEDBACK OVERNIGHT
WITH SOUTHERN IA/NORTHERN MO VORT...CREATING HIGHER PRECIP TOTALS
ACRS CENTRAL IL THEN THE ETA. PROGGED CONVERGENT MID LEVEL QG
FIELDS AND POS DEEP LAYER OMEGAS PEAK AROUND 00Z THIS EVENING...BUT
WITH LATE TROUGH PASSAGE WILL MAKE PRECIP MENTION FOR ALL NIGHT. AS
FOR THUNDER...FEEL EXTENT OF THREAT NOT WORTH MENTIONING. WILL GO
WITH JUST SHOWER WORDING OVERNIGHT...ALTHOUGH FORECAST SOUNDINGS DO
SUGGEST THAT SLIGHTLY ELEVATED INSTABILITIES WILL BE LOW ENOUGH FOR
A LITTLE THUNDER NOW AND THEN. AGAIN DEEP AND SUSTAINED CONVECTION
POSSIBILITIES AT QUESTION. AS MAIN SFC LOW SWEEPS ACRS WI LATE
TONIGHT...SOME DRY SLOTTING IN-FEED MAY WHIRL ACRS THE CWA FROM THE
SOUTHWEST FOR LESS OF A PRECIP CHANCE LATE.

SUNDAY HIGH TEMPS WILL BE TRICKY...WITH TIMING OF INCOMING BUT
LAGGING COLD AIR SURGE BEHIND SFC TROUGH. PROBABLY A LATE
MORNING/MIDDAY HIGH BEFORE TEMPS DROP OFF...AND AGAIN LIKE FWC
TEMPS HERE BEFORE CHILL DOWN. DAY LOOKS TO BE MAINLY DRY AS BRISK CAA
IN LOWER LAYERS COMMENCES IN THE AFTERNOON. DAY TO BE MAINLY
CLOUDY AS 130 KT+ H3 JET EXPRESS SURGES JUST TO THE SOUTH ACRS MO
AND SOUTHERN IL. MAIN DIGGING VORT INTO AMPLIFYING TROUGH TO CREATE
ITS MAIN UVV/POS OMEGA PUNCH ACRS TO THE NORTH OVER SOUTHERN MN
AND WI SUNDAY EVENING AND NIGHT. WITH CRASHING CRITICAL THICKNESSES
AND LOWER LAYER TEMPS...THIS FEATURE WILL BE A SNOW PRODUCER...BUT
AGAIN BULK OF THIS TO FALL TO THE NORTH AND NORTHEAST OF AREA OF
CONCERN. WILL BANK ON SOME CVA TO DIP SOUTH ENOUGH TO CREATE LIGHT
SNOW OR AT LEAST FLURRIES OVER THE NORTH HALF OF THE CWA SUNDAY
NIGHT.

MONDAY TO BE DRY AND DECREASING CLOUDS DAY...ALTHOUGH CHILLY WITH
PROGGED LLVL THERMAL PARAMETERS SUGGESTING THAT EVEN SOME AFTERNOON
INSOLATION WON'T HELP TEMPS BREAK THE 40 DEGREE MARK.

.LONGER RANGE(TUE-SAT)...MEDIUM RANGE MODELS SHOWING SOME CONSENSUS
AT BEGINNING OF EXTENDED PERIOD/MID WEEK...AND WILL LEAN TOWARD
ECMWF/UKMET GENERAL BLEND. L/W TROUGH STARTS TO SHIFT EAST ON TUE
FOR LOCAL TEMP RECOVERY TO AROUND 50...EVEN AFTER COLD START TO DAY.
WED STILL LOOKS LIKE WINNER OF THE WEEK AS STRONG RETURN FLOW...AHEAD
OF NEXT RIDGE PUMMELING WAVE FROM THE WEST COAST...BOOSTS TEMPS TO AT
LEAST AROUND 60. MID 60S COULD BE A POSSIBILITY LOOKING AT UKMET AND
EVEN MRF PROGGED LLVL THERMAL PARAMETERS. THIS NEXT WAVE WILL LOOK TO
DIG OVER THE UPPER MS RVR VALLEY ON THU AND FEEL BETTER PRECIP CHANCE
THAN MEX OR FWC POPS INDICATE. ANOTHER ROUND OF STIFF CAA TO SEEP
INTO TROUGH BASE FOR FRI AND SAT. TEMPS MAY NOT GET OUT OF THE 30S AS
IT LOOKS NOW...BUT MAY TREND TO AROUND 40 FOR NOW. ALSO POSSIBILITY
FOR FLURRIES OR LIGHT SNOW FRI AND FRI NIGHT IF ADEQUATE CVA DROPS
ACRS AREA IN AMPLIFYING CYCLONIC FLOW...BUT MAY KEEP DRY FOR NOW.

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

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