[LeArc] Forecast Discussion : MLI@ 5/2/2003 4:59:40 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 020957
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
450 AM CDT FRI MAY 2 2003

VORT SEEN ON LATEST W/V LOOP PUSHING ACRS IA KICKING UP SCATTERED
SPRINKLES AND LIGHT SHOWERS ON ITS NORTHERN GRADIENT FRINGE OVER
NORTHEAST IA...INTO FAR NORTHERN IL AND SOUTHERN WI. ALTHOUGH NOT
MUCH SEEN TRANSLATING TO THE GROUND IN SFC OBS...WILL MENTION AT
LEAST SPRINKLES THIS MORNING OVER THE NORTHERN THIRD OF THE CWA.
INCREASING DRY NORTHEAST SFC/LLVL FETCH WILL ALSO BATTLE ANY
PRECIP FROM REACHING THE SFC. THIS NORTHEAST FLOW WILL ALSO SHUNT
WEAK SFC WAVE AND INVERTED TROUGH(SFC REFLECTION OF VORT ALOFT) NOW
OVER EAST IA TO THE SOUTH AS SFC HIGH BUILD ACRS THE GRT LKS. DRY
LOW DPT AIR FROM SFC TO H85 FROM NORTHEAST SHOULD HELP ERODE SOME OF
THE CLOUDS ACRS THE NORTHEAST CWA THIS AFTERNOON...BUT THIS MAY BE
OPTIMISTIC. MOST OF THE CWA TO REMAIN CLOUDY/MOSTLY CLOUDY WITH
ENOUGH LINGERING RH IN THE H85-H7 MB LAYER TIL THIS EVENING. TEMPS
IN THE 60S MAY BE ALSO OPTIMISTIC...AND HAVE UNDERCUT MOST
GUIDANCE...OR LEANED TOWARD THE COOLER MAV GUIDANCE HIGHS FOR TODAY
WITH CLOUD COVER AND INCREASING GRT LKS FETCH OVER/INTO THE
LOCAL FORECAST AREA. WET GROUND FROM RECENT RAINS ALSO A THERMAL
ROBBING FACTOR.

WILL BANK ON DRY SUBSIDING AIRMASS BEHIND EXITING VORT TO THE
SOUTHEAST...TO HELP THINGS CLEAR OUT TONIGHT. WITH SFC RIDGE AXIS
DROPPING OVER THE MID LAKES CONTINUING TO SQUEEZE COOL DRY AIR
INTO THE AREA FROM THE NORTHEAST...STILL LOOKS LIKE A CHILLY NIGHT
IN-STORE FOR THE CWA AND HAVE UNDERCUT MOST GUIDANCE. FEEL AIRMASS
AND TEMPERATURES OVER EAST CENTRAL AND NORTHEAST WI ATTM(MID TO
UPPER 30S)...IS GIVING HINT AT WHAT'S POSSIBLE FOR SAT MORNING LOWS
OVER THE NORTHEAST 2/3'S OF THE CWA. FAR NORTHEAST IA AND NORTHWEST
IL STILL MAY BE OPEN TO SOME PATCHY FROST...BUT WILL NOT GO WITH
HEADLINES/ADVISORY JUST YET WITH WIDESPREAD LOWER 30S NOT
ANTICIPATED. DAY SHIFT WILL HAVE TO FURTHER ASSESS.

BRIEF BOUT OF UPPER RIDGING TO BRING ABOUT FAIR WX DAY ON SAT. SOME
SLIGHT THERMAL RECOVER EXPECTED WITH BACKING LLVL FLOW TO EAST-
SOUTHEAST. STILL NOT THE WARMEST OF FLOWS...AND EXPECT MAINLY LOW TO
MID 60S EVEN WITH SOME SUNSHINE. FAR SOUTHWEST CWA MAY APPROACH THE
70 DEGREE MARK THOUGH.

FIRST WAVE OUT OF WEST COAST L/W TROUGH IS PROJECTED BY SHORT RANGE
MODELS TO PROPAGATE INLAND AND ROLL ACRS THE CENTRAL PLAINS IN NEG
TILTED FASHION BY LATE SAT NIGHT/SUNDAY MORNING. LIKE GFS AND
UKMET SOLUTION OF DEEPENING SFC LOW AND MOVING IT TO THE NORTHEAST
NE/FAR NORTHWEST IA VCNTY BY 00Z MON...ALTHOUGH UKMET MATCHES UP
BETTER WITH H5 FEATURES AND CLOSED OFF UPPER LOW WITH ETA.
INTENSIFYING LOW TO INDUCE BRISK SOUTHEAST GRADIENT OVER THE CWA
FOR AT LEAST BREEZY CONDITIONS SUNDAY. ETA MAY BE OVERDOING SFC WIND
STRENGTH COMPARED TO GFS AND UKMET...BUT STILL LOOKS BRISK. FIRST
VORT COMPLEX TO SWEEP UP FROM THE SOUTHWEST OVER THE CWA FROM LATE
SAT NIGHT AND SUNDAY...ACCOMPANIED BY LLVL THERMAL GRADIENT AND
ELEVATED THTA-E ADVECTION AND CONVERGENCE. IMPRESSIVE SSE 40-50 KT
H85 FLOW THERMAL ADVECTING AND CONVERGING AS IT PUSHES AND BUILDS
NORTH SUNDAY OVER THE AREA. THIS WOULD SUGGEST AN ELEVATED BAND OF
RAIN AND EMBEDDED THUNDER TO PUSH ACRS THE CWA ON SUNDAY...BUT BRISK
SOUTHEAST SFC FLOW TAPPING BACK INTO SOMEWHAT DRIER AIR MAY RETARD
PRECIP APPROACH. WILL STILL BUMP UP TO HIGH CHANCE POPS FOR SUNDAY.
WARM FRONT...OR EVEN MORE LIKE OCCLUDED FRONT TO WRAP UP OVER THE CWA
LATER SUNDAY NIGHT. BEFORE IT DOES...INTERESTING EXTENT OF STORM REL
HELICITIES PAINTED BY FORECAST SOUNDINGS SUNDAY AFTERNOON OVER THE
SOUTH HALF.

NO CHANGES TO LONGER RANGE(SUNDAY NIGHT ON) FOR NOW...

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

$$

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