[LeArc] Forecast Discussion : MLI@ 2/7/03 4:42:43 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 071051
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
445 AM CST FRI FEB 7 2003

LARGE ELONGATED VORT COMPLEX TO CONTINUE TO PUSH SOUTH OF THE AREA
TODAY...WITH DRYING AND SUBSIDENCE REGIME TO FOLLOW IN BEHIND IT
WITH ARCTIC AIRMASS. THUS SUNNY BUT COLD DAY IN STORE FOR THE CWA
TODAY. FAR NORTHEAST CWA MAY GET CLIPPED BY SOME CU OUT OF WI EARLY
THIS MORNING...BUT GENERALLY CLOUDS NOT TO BE A FACTOR.  CONCERN
RIGHT OFF THE BAT IS PORTIONS OF THE NORTHWEST CWA APPROACHING OR
EXCEEDING WIND CHILL ADVISORY CRITERIA OF -20 F ATTM. EXPECT WIND TO
DIP BELOW SUSTAINED 10 MPH CRITERIA THROUGH 13Z OVER MOST OF NORTHERN
CWA THROUGH SUNRISE WHERE COLDEST AMBIENT TEMPS ARE OCCURRING...THUS
EXPECT SEVERE WIND CHILL THREAT/APPROPRIATE WIND SPEEDS TO NOT BE
WIDESPREAD ENOUGH AND SHORT LIVED TO WARRANT AN ADVISORY. WILL STILL
HIT HARD IN HWO AND HAVE ALREADY ADDED EARLY MORNING WIND CHILLS IN
FIRST PERIOD.

CWA STARTS OFF THIS MORNING UNDER -20 C H85 COLD POOL...BUT BACKING
LLVL FLOW AS DAY PROGRESSES TO SHUNT THIS TO THE EAST. THERMAL
RECOVERY TO BE SLOW AT THE SFC THOUGH...AS RIDGE AXIS SETTLES ACRS
CWA FOR MOST OF DAY FOR MINIMAL MIXING. SOUTHWEST RETURN FLOW MAY
KICK IN BY LATE AFTERNOON ACRS THE WEST...BUT NOT REALLY ENOUGH TO
HELP TEMPS GET MUCH HIGHER THAN LOW TO MID TEENS...EVEN WITH FULL
INSOLATION AND MINIMAL SNOW COVER. NEXT MAIN WAVE OF CONCERN TO SHEAR
DOWN ACRS THE GRT LKS SAT AFTERNOON AND NIGHT...IN RE-AMPLIFYING
NORTHWEST FLOW AS REX BLOCK CONTINUES TO SETTLE OFF THE WEST COAST.
LLVL BAROCLINIC AND RH RIBBON ASSOCIATED WITH THIS FEATURE...WILL
LOOK TO SWEEP DOWN SOUTH ACRS THE AREA ON SAT. BEFORE IT DOES...SHOT
OF LLVL WAA TO INCREASE AHEAD OF IT OVERNIGHT AND INTO SAT MORNING.
THUS EXPECT BRIEF TEMP DROP OFF JUST AFTER SUNSET THIS EVENING...
BEFORE INCREASING GRADIENT AND SOUTHWEST WINDS AHEAD OF INCOMING COLD
FRONT ALLOW TEMPS TO RECOVER OVERNIGHT AND INTO SAT MORNING. MIDDAY-
EARLY AFTERNOON HIGHS ON SAT MAY STRIVE INTO THE UPPER 20S TO LOWER
30S BEFORE FROPA.

SAT PRECIP THREAT:ISENTROPIC ANALYSIS OF THE 285K SFCS SUGGEST BRIEF
BOUGHT OF LIFT SAT MORNING FOLLOWED BY DOWNSLOPING REST OF DAY...THUS
NOT VERY IMPRESSIVE. LOOKING AT EXTENT OF CONDENSATION PRESSURE
DEFICITS...AVN-GFS MUCH MORE BULLISH ON SATURATION ON SAT THAN ETA...
AND CREATES MORE QPF. ETA AND NGM QUICKER WITH PROCESS OF SWEEPING
FORCING AND BAROCLINIC RIBBON SOUTH THROUGH THE CWA THAN THE GFS...
BUT ALL SUGGEST ENOUGH POS OMEGAS...MID LEVEL CONVERGENT QG
FORCING...AND FRONTOGENETICAL FORCING IN LOWER LEVELS TO MILK OUT
LIGHT SNOW OR FLURRIES...EVEN THOUGH LACK OF MOISTURE TO BE A PLAYER.
WILL UP FLURRY WORDING TO CHANCE POPS OF LIGHT SNOW ACRS THE NORTHERN
2/3'S...ALTHOUGH EXPECT MINIMAL ACCUMULATIONS OF DUSTING TO A FEW
TENTHS. SOME LINGERING FLURRIES SAT EVENING...BEFORE NEXT BOUT OF
SUBSIDENCE AND SOME CAA FILTERS IN FROM THE NORTHERN PLAINS. SHOULD
BE BRIEF...AS IT STILL LOOKS LIKE NEXT DISTURBANCE/CLIPPER TO RIDE IN
ON MERIDIONAL FLOW FOR NEXT SNOW CHANCE SUNDAY AFTERNOON.

NO CHANGES TO LONGER RANGE.

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

$$

12