[LeArc] Forecast Discussion : MLI@ 6/3/2003 2:56:05 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 031954
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
250 PM CDT TUE JUN 3 2003

CUT-OFF UPPER LOW AND ASSOCIATED VORT WILL CONTINUE TO GYRATE OVER
THE AREA OVERNIGHT...AND SHOULD KEEP WIDELY SCATTERED SHOWER
ACTIVITY GOING ON ALONG VORT GRADIENT OVER MUCH OF THE
OF THE CWA THROUGH AT LEAST MID EVENING. CLOUD COVER AND SUBSEQUENT
FOG AND LOW TEMP POTENTIAL TO BE MAIN QUESTION TONIGHT. SHORT
RANGE MODELS INDICATE BACKING EAST LLVL FLOW TO THE NORTHEAST...TO
HAVE DRIER INFLUX/SOME SCOURING EFFECT ACRS THE NORTHEAST HALF TO 1/3
OF THE CWA. WOULD EXPECT AT LEAST SOME PARTIAL CLEARING AFTER
INSOLATION LOSS AND THUS LOWER TEMPS IN THESE AREAS(MID UPPER 40S)...
WITH POTENTIAL OF PATCHY GROUND FOG. FEEL FOG POTENTIAL NOT
WIDESPREAD OR SUBSTANTIAL/DENSE ENOUGH FOR ZONE MENTION THOUGH.

WATER VAPOR LOOP SHOWING NEXT UPSTREAM VORT NICELY OVER THE
DAKOTAS...AND APPEARS TO BE ON A TRACK TO ROTATE EAST-SOUTHEAST
OVER THE AREA ON WED. BUT SHORT RANGE MODELS SEEM TO GET
LOST WITH/MISHANDLE THIS WAVE EVOLVEMENT. PORTIONS OF IT GET INGESTED
INTO COMPLEX CURRENTLY OVER THE AREA...WHILE THE BULK OF IT STARTS TO
GET SUCKED BACK NORTH BY APPROACHING AND MUCH MORE VIGOROUS WAVE
DROPPING DOWN ACRS SASKATCHEWAN. IF MODELS ARE WRONG AND UPSTREAM
WAVE MAKES IT ACRS...MAY BE ENOUGH UPPER SUPPORT WITH STEEP LLVL
LAPSE RATES FOR SOME WIDELY SCATTERED SHOWERS BY WED AFTERNOON. IF
SYSTEM DISSOLVES OR HOLDS BACK SUDDENLY...STILL MAY BE ENOUGH EFFECT
OFF WEST LOBE OF SLOWLY MIGRATING MAIN VORT ALREADY IN PLACE FOR A
SHOWER CHANCE. THUS WILL TOY WITH INTRODUCING LOW POPS FOR THIS
POSSIBILITY. WITH STEEP 1000-H85 MB LAPSE RATES AND ENOUGH LINGERING
RH'S...SEEM PARTLY TO MOSTLY CLOUDY SKIES TO REMAIN WITH TEMPS
REMAINING IN THE 60S...UNTIL SOME CLEAR OUT WITH ARRIVAL OF SFC RIDGE
AXIS WED NIGHT. WITH LIGHT/CALM WINDS...BREAK IN SKY COVER...AND ANY
LINGERING SFC MOISTURE...MAY BE BETTER FOG POTENTIAL FOR EARLY THU
MORNING. WILL LEAN TOWARD...OR EVEN UNDERCUT COOLER FWC LOWS FOR THU
MORNING. THE COOL NIGHTS OF JUNE CONTINUE.

AS SFC RIDE RETREATS TO THE SOUTHEAST ON THU...SOME RETURN FLOW TO
DEVELOP AHEAD OF NEXT MAJOR UPSTREAM WAVE(ABOVE MENTIONED
SASKATCHEWAN VORT). WITH SOME MODERATION AND AT LEAST PARTLY SUNNY
SKIES BEFORE NEXT ONSLAUGHT OF CLOUD COVER BY LATER THU AFTERNOON
AHEAD OF APPROACHING SYSTEM...WOULD EXPECT TEMPS TO BREACH THE 70
DEGREE MARK. WITH LLVL RIDGE COMPLEXES TO THE SOUTH OF THE AREA
TEMPORARILY BLOCKING BETTER LLVL MOISTURE FEED/RETARDING ADEQUATE
SATURATION...WOULD THINK PRECIP ASSOCIATED WITH LATE SPRING
CLIPPER WOULD HOLD OFF UNTIL THU NIGHT. ETA SUGGESTING SOME NICE
1000-H85 MB THTA-E ADVECTION AND CONVERGENCE PUSHING ACRS THE WESTERN
CWA BY 00Z FRI. POS OMEGAS EXPLODE AFTER 00Z FRI OVER THE AREA AS
WELL...AND EXTENT OF MID LEVEL LAPSE RATES SUPPORT THUNDER WORDING.

.LONGER RANGE(FRI-TUE)...WILL TAKE GENERAL BLEND OF LATEST ECMWF AND
MRF TO RIDE OUT EXTENDED PERIOD. LOOKS LIKE LIKELY PRECIP EVENT ON
FRI...AS BOTH MODELS CONTINUE TO SPILL UPPER VORT DOWN IN NORTHWEST
FLOW ALOFT ACRS THE UPPER MS RVR VALLEY. EUROPEAN SOLUTION INDICATES
MAIN SFC LOW WILL PASS SOUTH OF THE CWA OVER MO WITH INVERTED TROUGH
TO THE NORTH...WHILE EX. GFS HAS NORTHERN PORTION OF TROUGH WITH MAIN
SFC LOW. ECMWF SOLUTION WOULD SUGGEST MUCH OF THE LOCAL AREA
EXPERIENCING MORE OF A OVERRUNING RAIN EVENT. IF THIS SOLUTION PANS
OUT...PRECIP AND EAST FLOW TO THE NORTH OF THE SYSTEM SUGGEST TEMP
GUIDANCE TOO WARM. XGFS SUPPORTS L0WER 70S EVEN WITH CLOUD COVER AND
PRECIP. WILL TAKE BLEND. TEMPORARY RIDGING BETWEEN UPPER SYSTEMS WILL
THEN MAKE FOR A FAIR SATURDAY. NEXT UPPER SYSTEM OF CONSEQUENCE TO
DROP DOWN OVER IA AND IL FOR ANOTHER PRECIP THREAT SUNDAY. MRF DIGS
THIS SYSTEM FURTHER SOUTH THAN THE EURO OR UKMET...BUT BOTH THESE
MODELS CUT-OFF UPPER LOW SOONER THAN THE MRF...WHICH MAINTAINS OPEN
WAVE UNTIL LATE MONDAY. NORTHWARD PLACEMENT AND TRACK OF SFC SYSTEM
AT QUESTION...AND WOULD OF COURSE ALTER HEAVIER QPF BAND. BIT FURTHER
SOUTH MRF EVEN SUGGESTS POTENTIAL FOR SIGNIFICANT OVERRUNNING EVENT
AS MAIN SFC LOW RIMS THE SOUTH AND EASTERN CWA. WILL KEEP SHOWER/
STORM CHANCE FOR NOW....AND AWAIT FURTHER RUNS. MRF INDICATING
SLOWING/CUTTING OFF OF UPPER SYSTEM TO LINGER SHOWERS INTO MONDAY...
WHILE UKMET AND EURO OPEN UP THE WAVE AND SHUNTING IT QUICKER OFF TO
THE EAST. WILL TREND TOWARD THE SLOWER EVOLVEMENT AND KEEP PRECIP
CHANCE AT LEAST INTO EARLY MONDAY. AS YET ANOTHER NORTHWEST FLOW
SYSTEM ORGANIZES ACRS SOUTH CENTRAL CANADA EARLY NEXT WEEK...IT
SHOULD DRAW WARMER AIR UP OUT AHEAD OF IT FOR REBOUNDING HIGHS
PUSHING THE 80 DEGREE MARK NEXT TUESDAY.

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

$$

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