[LeArc] Forecast Discussion : MLI@ 4/12/2003 4:43:11 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 120941
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
430 AM CDT SAT APR 12 2003

HOW WARM OR HOW COOL MAIN FORECAST CHALLENGE OVER NEXT FEW DAYS IN
CONTINUING FAIR WX PATTERN. LATEST MSAS LOOP..SFC OBS AND EVEN IR
IMAGERY INDICATING ARRIVAL OF BACKDOOR COOL FRONT ACRS THE EASTERN
HALF OF THE CWA. LOWER DPTS INFILTRATING THE AREA FROM THE NORTHEAST
AS WELL WITH AIRMASS EXCHANGE. W/V LOOP INDICATING VORT DROPPING
SOUTH OVER THE NORTHERN CWA ATTM...DOING LITTLE IN MOISTURE STARVED
VERTICAL COLUMN. FEATURE WILL CONTINUE TO SHEAR SOUTH AND EAST OVER
THE AREA TODAY AS UPPER RIDGE AXIS SETTLES OVER THE EASTERN PLAINS.
THIS RIDGE WILL CONTINUE TO BUILD OVER THE UPPER MS RVR VALLEY
THROUGH SUNDAY...KEEPING MAIN VORT TRACK SHUNTED WELL TO THE NORTH
ALONG THE CANADIAN BORDER THROUGH MONDAY...FOR CONTINUED BENIGN WX
PATTERN IN THE NEAR TERM.

LIGHT NORTH-NORTHEAST FLOW AT H85 MB WILL GLANCE THE CWA WITH LLVL
COOL POOL OFF GRT LKS RIDGE AXIS TODAY...AND SHORT RANGE MODEL
ENSEMBLE OF LLVL THERMAL PROFILES AND EXPECTED LAKE EFFECT INLAND
FETCH SUGGEST TEMP SPREAD OF AROUND 60 DEGREES ACRS THE NORTHEAST CWA
THIS AFTERNOON...TO AROUND 70-LOWER 70S IN THE FAR SOUTHWEST. BUT
FEEL WITH EXTENT OF DRY AIRMASS...APRIL INSOLATION AND EXPECTED
MIXING...MAY GO A CATEGORY HIGHER THAN THAT GENERAL TEMPERATURE
SPREAD FROM NORTHEAST...TO THE WEST AND THE SOUTH. AS PREVIOUS SHIFT
NOTED THAT GRT LAKE EFFECT LOOKS TO BE MARGINAL TODAY...AND WITH
PREVIOUS TWO DAYS OF TEMP BUSTS ON HIGH SIDE...WILL PLAY WARMER. OF
COURSE YESTERDAY'S PRE-FRONTAL COMPRESSIONAL HEATING HELPED AND THAT
PROCESS WON'T BE A FACTOR TODAY...BUT AGAIN DRY AND WARM-ABLE
AIRMASS...AND MIXING WITH FULL MID APRIL INSOLATION SUGGEST A BLEND
OF WARMER FWC AND MET TEMP GUIDANCE FOR SAT AFTERNOON HIGHS. THE MET
TEMPS HAVE BEEN THE BEST BY FAR OVER THE PAST TWO DAYS IN A WARMING
SCENARIO. IF NORTHEAST WIND AND CAA BECOME MORE ROBUST THAN CURRENTLY
EXPECTED...THAN PACKAGE HIGHS WILL BE TOO WARM IN THE FIRST PERIOD.

SHORT RANGE MODELS SUGGEST THAT H85 FLOW TO FLIP/QUICK-VEER TO THE
WEST-SOUTHWEST BY LATE TONIGHT...AND THEN BACK ON SUNDAY AND
INCREASE. STILL EXPECT COOL NIGHT TONIGHT AT THE SFC THOUGH...WITH
SUNDAY MORNING LOWS POSSIBLY REFLECTING WHAT'S GOING ON NOW ACRS EAST
CENTRAL WI...LOW-MID 30S. AT LEAST THE H85 FLOW SWITCH ALOFT IS THE
INITIALIZATION OF NEXT WARM-UP AND EVENTUAL TAP INTO LLVL WARM
THERMAL POOL THAT WILL BE BUILDING ACRS THE PLAINS. ALTHOUGH LEARY OF
DEVELOPING SOUTHEAST SFC FLOW TAPPING BACK/RECYCLING INTO RIDGE AXIS
AIRMASS PRECLUDING REAL WARM-UP...STILL EXPECT SFC WINDS TO BECOME
SOUTH-SOUTHEAST AND INCREASE TO ALMOST BREEZY STATUS BY MID
AFTERNOON...ESPECIALLY ACRS THE WESTERN CWA. THIS MIXING AND COMBINED
SUNSHINE SHOULD HELP BOOST TEMPS BACK INTO THE 70S...EVEN AFTER COOL
START(BIG DIURNAL SWING).

SOUTH BREEZE MAINTAINED BY INCREASING SFC GRADIENT OVER SUNDAY NIGHT
SHOULD HOLD UP MINS IN THE 50S...AND THERMAL POOL TAP WITH BRISK
MIXING SOUTHERLY SFC WINDS ON MONDAY SUGGESTS RECORD HIGHS WILL
FALL. WILL KEEP ONGOING LOW TO MID 80S AND RECORD WORDING FOR
MONDAY...BUT AGREE WITH PREVIOUS SHIFT THAT THOSE TEMPS MAY BE
CONSERVATIVE.

NO CHANGE TO LONGER RANGE.


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

$$

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