[LeArc] Forecast Discussion : MLI@ 2/28/03 5:03:44 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 281111
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
455 AM CST FRI FEB 28 2003

VORT COMPLEX...NOW SEEN ON W/V IMAGERY ROUNDING TROUGH BASE OVER THE
GRT BSN...WILL GET BUMPED ALONG BY UPSTREAM WAVES AND EJECT OUT IN
SOUTHERN STREAM TOWARD NORTHERN MO BY LATE TODAY. LATEST SHORT
RANGE MODEL RUNS SIMILAR IN VORT STRENGTH AND TIMING BY NOW...BUT
GFS-AVN PROGGED TO BRING NORTHERN EDGE OF VORT GRADIENT BIT FURTHER
NORTH THAN ETA SOLUTION. MAIN FEATURE/LEAD VORT "EJECTI" SKIRTS ALONG
AND JUST SOUTH OF THE IA/MO BORDER BY LATE TONIGHT AND INTO SAT
MORNING...AND APPEARS TO KICK UP ENOUGH FORCING FOR A PRECIP EVENT
ACRS AT LEAST THE SOUTHERN THIRD OF THE CWA. VERTICAL AND PLAN VIEW
OMEGA AND LMRH FIELDS OVERLAY SUGGEST BEST LIFT AND FORCING FROM
06Z-14Z SAT ACRS THE SOUTH HALF OF THE CWA ON NOSE OF INCOMING CVA...
WITH BEST POS OMEGA PUNCH OUT-RACING DEEPER COLUMN SATURATION. THUS
WOULD SUGGEST LIGHT SNOW/FLURRY EVENT...WITH MINOR ACCUMULATIONS.
MOST AREAS ALONG AND SOUTH OF I-80 TO GET MAINLY A DUSTING THROUGH
MIDDAY SATURDAY...BUT QUICK BURST OF MODERATE ISENTROPIC LIFT(LOOKING
AT 290-295 K SFC ANALYSIS) COMBINED WITH 2-3 G/KG SPECIFIC HUMIDITIES
SUGGEST A LOCALIZED STRIP OF UP TO AN INCH POSSIBLE FROM MEMPHIS
MO...TO SOUTH OF MONMOUTH IL. AM BIT HESITANT WITH ADEQUATE MOISTURE
AT QUESTION...BUT RAISED POPS ACRS THE SOUTH AND MID SECTIONS...AND
INTRODUCE SOME LIGHT ACCUMULATION POSSIBILITIES WHERE WARRANTED. BULK
OF PRECIP SHOW TO BE DONE BY SATURDAY AFTERNOON. INTERESTING LATEST
UKMET AND 06Z META TRENDS WITH BETTER PRECIP BANDS FURTHER NORTH ACRS
THE CENTRAL AND NORTHERN CWA BY LATE TONIGHT AND ON INTO SAT. DAY
CREW WILL HAVE TO ASSES HIGHER POP POTENTIAL FURTHER TO THE NORTH...
IF 12Z FRI MODEL TRENDS CONTINUE THIS WAY.

GETTING BACK TO TODAY...WENT ABOVE GUIDANCE(MID TO UPPER 30S) WHERE
SOME INSOLATION EXPECTED...MUCH LIKE YESTERDAY...WITH TRAJECTORIES
AND LLVL THICKNESS TRENDS SUGGESTING LITTLE AIRMASS CHANGE THROUGH
00Z SAT. BUILDING CLOUD COVER ACRS THE FAR SOUTH AGAIN...TO LIMIT
SFC THERMAL POTENTIAL THERE TO MID 30S.  WAA JUST ALOFT
OVERNIGHT INTO SAT NOT TO BE REALIZED FULLY TO THE SFC FOR SAT
HIGHS...AS CLOUD COVER AND PRECIP KEEP BULK OF CWA IN MID 30S. ANY
BREAKS IN THE STRATOCU ACRS THE NORTH ON SAT...MAY ALLOW THOSE AREAS
TO ATTAIN UPPER 30S AGAIN. VEERING H85/LLVL FLOW TO THE NORTHWEST
LATER SAT NIGHT INTO SUNDAY MORNING TO SIGNAL NEXT COLD AIR INFLUX
INTO THE REGION...AND LOOKING AT ETA THERMAL POTENTIAL...HAVE LOWERED
SUNDAY MORNING MINS TO OR BELOW FWC/MAV LOWS.  HAVE ALSO TRENDED DOWN
SUNDAY HIGHS...AND FEEL INCOMING CANUCK ANTICYCLONE TO LIMIT SNOW
CHANCE ON SUNDAY AND CLEAR THE AREA OUT. LEFT SUNDAY SNOW CHANCE FOR
NOW...BUT MAY NEED TO BE REMOVED BY LATER SHIFT. BEFORE
THEN(SUNDAY)...CYCLONIC FLOW ALOFT AND TRANSITION TO CAA REGIME TO
MILK OUT SOME FLURRIES ACRS THE NORTH HALF OF CWA LATER SAT NIGHT...
BUT LACK OF MOISTURE SUGGESTS DOWNGRADE OF MEASURABLE SNOW CHANCE TO
TRACE EVENT.

NO CHANGES TO LONGER RANGE.

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

$$

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