[LeArc] Forecast Discussion : MLI@ 3/11/03 5:03:12 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 111111
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
510 AM CST TUE MAR 11 2003

SYNOPTIC PICTURE THIS MORNING SHOWS WNW FLOW AT 500H ACROSS ENTIRE
U.S...WITH A 120KT JET DIVING SOUTHEAST OVER SOUTHERN MANITOBA.  AT
THE SURFACE...HIGH PRESSURE IS CENTERED OVER THE OHIO AND TENNESSEE
VALLEYS WITH A HIGH PLAINS TROF EXTENDING FROM A SOUTH DAKOTA LOW
INTO THE TEXAS PANHANDLE.

THE PRIMARY FORECAST CHALLENGE IS IN THE SHORT-TERM...WITH THE PLAINS
TROF SAGGING SOUTH ACROSS THE FORECAST AREA TONIGHT...AND REMAINING
IN THE AREA THROUGH WEDNESDAY NIGHT BEFORE BEING KICKED OUT TO THE
EAST.  TEMPERATURES WILL BEGIN A WARMING TREND TODAY...WITH ABOVE
NORMAL READING EXPECTED THURSDAY THRU MONDAY.

THE SHORT-TERM MODELS INITIALIZED MODERATELY WELL...WITH THE AVN
HAVING THE EDGE ON SURFACE FEATURES IN THE PLAINS.

THE MODELS AGREE ON THE TROF MOVING SOUTH THROUGH THE FORECAST AREA
TONIGHT. AFTER THAT THE ETA AND NGM STALL THE FRONT JUST SOUTH OF THE
FORECAST AREA WEDNESDAY...WITH A LOW MOVING OUT OF THE CENTRAL PLAINS
AND EAST ALONG THE FRONT ACROSS NORTHERN MISSOURI WEDNESDAY NIGHT...
WITH THE FRONT KICKING EAST BY 12Z THURSDAY MORNING.  THE AVN NEVER
GETS THE FRONT QUITE SOUTH OF THE FORECAST AREA...SO IT LINGERS
ACROSS THE SOUTH FOR 24 HOURS BEFORE GETTING KICKED EAST. SINCE THE
AVN HAS HANDLED SURFACE FEATURES BEST OVERNIGHT...WILL LEAN TOWARDS
ITS SOLUTION.  MODERATE VV'S AND UPPER DIFFLUENCE ARE OVER THE AREA
THIS EVENING AS THE FRONT SINKS SOUTH...BUT MOISTURE WILL BE
LIMITED.  WEDNESDAY EVENING WILL BE A DIFFERENT CASE...WITH
STRONGER VV'S AND UPPER DIFFLUENCE...DUE TO LEFT EXIT REGION OF A
130KT JET OVER MANITOBA AND MINNESOTA...AND SURFACE DEW POINTS 10
DEGREES HIGHER THAN 24 HOURS BEFORE. BEST CHANCES FOR PRECIP WILL BE
FROM 21Z WEDNESDAY AFTERNOON TIL BETWEEN 06Z AND 09Z WEDNESDAY
NIGHT...WHEN SURFACE LOW PASSES SOUTH THROUGH UIN...AND 500MB TROF
PASSES OVER DVN.

LOOKING FURTHER AHEAD...A RIDGE WILL BUILD BACK INTO THE REGION AT
500MB THURSDAY AND FRIDAY.  AFTER THAT THE MEDIUM-RANGE MODELS ARE
ALL OVER THE PLACE...INDICATING RIDGING OR ZONAL FLOW THROUGH THE
REMAINDER OF THE EXTENDED PERIOD.  TEMPERATURES WILL WARM UP QUITE A
BIT ON A SOUTHWEST FLOW BETWEEN A LARGE SOUTHEASTERN HIGH AND A
PLAINS TROF.  UPPER DISTURBANCES MOVING FROM SOUTHWEST TO NORTHEAST
THROUGH THIS FLOW WILL BRING A CHANCE OF SHOWERS SUNDAY AND AGAIN
MONDAY.

WILL STAY CLOSE TO OUR CURRENT FORECAST...INTRODUCING A CHANCE OF
RAIN ON WEDNESDAY. TEMPS WEDNESDAY AND WEDNESDAY NIGHT WILL BE
TRICKY...BECAUSE IF FRONT DOESN'T MAKE IT ALL THE WAY THRU THE
FORECAST AREA...TEMPS SOUTH COULD BE A CATEGORY OR TWO HIGHER.

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

$$

REA