[LeArc] Forecast Discussion : MLI@ 3/1/03 5:02:37 AM

Sat, 01 Mar 2003 05:02:37 -0600

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

FXUS63 KDVN 011110
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
459 AM CST SAT MAR 1 2003

LOCAL AND REGIONAL 88D LOOPS INDICATING LIGHT SNOW/FLURRIES SPREADING
NORTH ACRS THE CWA ATTM...BUT BARK WORSE THAN THE BITE WITH SFC
OBS INDICATING ACTIVITY HAVING TROUBLE REACHING THE SFC...OR TOO
LIGHT TO MEASURE. THIS ACTIVITY BLOSSOMING ON NORTH END OF NORTHEAST
MO/CENTRAL IL VORT...AND WILL GO LIKELY POPS OVER MOST OF THE CWA...
ALTHOUGH SHOULD BE LIGHT/MINIMAL PRECIP EVENT WITH MOST OF AREA JUST
GETTING A TRACE TO A FEW HUNDREDTHS OF AN INCH OF SNOWFALL. AS VORT
SHEARS EAST...ACTIVITY SHOULD WANE ACRS THE SOUTH BY LATE MORNING...
AND THE EAST/NORTHEAST CWA BY EARLY AFTERNOON. AFTER PRECIP ENDS...
PROJECTED SOUNDINGS SUGGEST LIGHT SOUTH BREEZE AND SOME MIXING
SHOULD HELP TEMPS CLIMB INTO THE MID TO UPPER 30S THIS AFTERNOON...
EVEN WITH CLOUD COVER HANGING ON. MAV AND FWC TEMP GUIDANCE MAY
FINALLY BE WARM ENOUGH TODAY AND LOOKS REASONABLE.

SHORT RANGE MODELS NOW FURTHER NORTH THAN LAST NIGHTS 00Z RUNS WITH
EJECTION PROCESS OF SECONDARY VORT...NOW SEEN ON W/V IMAGERY ROUNDING
TROUGH BASE OUT OF THE GRT BSN. MODELS NOW GENERALLY SWING THIS
FEATURE JUST TO THE SOUTH AND EAST OF THE CWA THIS EVENING...BUT
BEST POS OMEGA PUNCH AND FORCING TO OCCUR ON FEATURES' NOSE AND SOUTH
VORT GRADIENT SIDE...WHICH WOULD KEEP SNOW BANDING TO THE SOUTH OF
THE CWA FROM JUST NORTH OF KLSX...AND INTO CENTRAL IL. WILL STILL GO
WITH LOWER POPS FOR LIGHT SNOW POSSIBILITY IN WEST CENTRAL IL/FAR
SOUTHEAST CWA THIS EVENING IN CASE NORTHERN PORTION OF VORT GRADIENT
KICKS UP SOME PRECIP. AS CYCLONIC FLOW DIGS ACRS THE MIDWEST
OVERNIGHT...ELONGATED VORT STRUCTURE EMBEDDED IN THIS FLOW WILL
ACCOMPANY INCOMING CAA SURGE IN THE LOWER LEVELS AND STILL LOOK TO
WRING OUT A FEW FLURRIES OVERNIGHT...ESPECIALLY AFTER THE BEWITCHING
HOUR.

INCOMING COLD SURGE AT SFC TO INDUCE STEEP LLVL(1000-900 MB) LAPSE
RATES ON SUNDAY...ESPECIALLY ACRS THE EAST HALF OF THE CWA. SHOULD
SET UP OPTIMUM MIXING SCENARIO FOR BRISK/WINDY CONDITIONS...AND
ENOUGH LINGERING RH FOR CU GENERATION. AM UNSURE OF EXTENT OF
INSTABILITY SNOW FLURRIES/SHOWERS THAT COULD BE GENERATED THAT
PREVIOUS SHIFT INITIATED...ESPECIALLY WITH INCOMING DRYING AND
SUBSIDENCE ADVERTISED BY MODELS AND LOW SFC DPTS. BUT LIKE PREVIOUS
SHIFT STATED THAT THIS BRISK MIXING AND THERMAL MICRO FLUX NOT
HANDLED BY MODELS AND CAN'T ARGUE AGAINST AT THIS POINT...THUS HAVE
ELECTED TO LEAVE PARTLY CLOUDY WITH SCATTERED FLURRIES FOR NOW FOR
SUNDAY.

INTERESTING TO NOTE STRONG CONVERGENT QG FORCING PUSHING OVER THE
CWA IN THE H85-H5 LAYER BY LATE SUNDAY NIGHT IN BUILDING WAA ALOFT.
STILL LOOKS LIKE "CLIPPER'S AWAY" FOR LATER MONDAY.

NO CHANGE TO LONGER RANGE

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

$$

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