[LeArc] Forecast Discussion : MLI@ 9/16/02 2:33:43 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 160741
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
235 AM CDT MON SEP 16 2002

LATEST MSAS INDICATING LIGHT MOISTURE CONVERGENCE ACRS WEST CENTRAL
IL INTO SOUTH CENTRAL IL...ON LEE SIDE OF RIDGE AXIS NOW SETTLING
OVER WEST CENTRAL IA...INTO SOUTHERN WI. THIS CONVERGENCE...ALTHOUGH
SUBTLE...IS COMBINING WITH CLEAR SKIES AND LINGERING AREA OF HIGHER
SFC DPTS IN COOLING REGIME ENOUGH TO FORM PATCHY DENSE FOG ACRS
CENTRAL IL INTO SOUTHEAST CWA. WILL WATCH TRENDS TOWARD ISSUANCE TIME
ON IR FOG LOOP AND SFC OBS...BUT FOR NOW WILL PLAN ON COVERING WITH
EARLY MORNING WORDING IN SOUTHERN ZONES AS OPPOSED TO AN ADVISORY.

OTHERWISE...TEMPORARY SHARP UPPER RIDGING TO PROVIDE FAIR STRETCH OF
WX(LIKE WE HAVEN'T HAD ENOUGH THIS MONTH) THROUGH TUE...BEFORE
VIGOROUS WEST COAST L/W TROUGH PROGRESSES INLAND FOR A MORE UNSETTLED
MID TO LATE WEEK PERIOD. THIS WAVE WILL EVENTUALLY TRY TO BUCK MID
CONUS RIDGE BY TUE NIGHT...AND SHORT RANGE MODELS SUGGEST IN DOING SO
BECOMING NEG TILTED. SHORT RANGE MODELS ALSO SUGGEST FIRST GOOD BOUT
OF CVA TO ROLL ACRS THE CWA FROM THE SOUTHWEST BY LATE TUE NIGHT.
BEFORE THEN...MAIN FORECAST CONCERNS IN THE NEAR TERM  IN BENIGN WX
PATTERN WILL BE TEMPS. BACKING H85 FLOW TO TAP INTO WARMER THERMAL
POOL TO THE WEST ACRS THE HIGH PLAINS TODAY...WITH H85 TEMPS
CONSERVATIVELY RECOVERING TO AROUND THE +15 C RANGE. WITH INSOLATION
AND EVEN WEAK MIXING...LOW 80S SHOULD BE REACHED. BUT COOL START TO
DAY MAKES FOR LARGE DIURNAL JUMP TO HURDLE TO REACH THESE VALUES...
AND MAY KEEP UPPER 80S OR AROUND 80. DEEP DRY COLUMN DOES SUPPORT
POTENTIAL FOR DIURNAL SURGE TO BE MADE...AND WOULD NOT BE SURPRISED
IF A FEW LOW 80S OR EVEN AN 83 REACHED SOMEWHERE ACRS THE CWA. WILL
GO WITH MAV/FWC BLEND FOR LOWS TONIGHT...THE'RE CLOSE ANYWAY AND LOOK
REASONABLE. MAY STILL HAVE TO UNDERCUT SOME OF THOSE LOWS ACRS THE
FAR EAST THOUGH...DUE TO THE SAME DRY AIRMASS REASONING MENTIONED
ABOVE.

BETTER SHOT TO BREACH WELL INTO THE 80S ON TUE...AND WILL GO ABOVE
GUIDANCE WHICH GENERALLY KEEPS CWA IN UPPER 70S AGAIN. H85 WARM FRONT
PUSHES UP TOWARD IA/MO BORDER BY 12Z WED...AND WITH EXTENT OF H85
THTA-E ADVECTION AND CONVERGENCE PROGGED TO BUILD TOWARD SOUTHERN CWA
BY LATE TUE NIGHT...COMBINED WITH UPPER VORT SUPPORT...MAY THROW LATE
NIGHT CHANCE IN FOR ELEVATED CONVECTION IN SOUTHERN ZONES. REST OF
LONGER RANGE WILL NOT BE TOUCHED FOR NOW...BUT IF MODELS KEEP TREND
OF SWEEPING STRONG FORCING EVENT/NEG TILTED WAVE OVER THE CWA WED
NIGHT...AT LEAST LIKELY POPS WILL NEED TO BE INTRODUCED BY LATER
SHIFTS.

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

JDH