[LeArc] Forecast Discussion : MLI@ 5/28/2003 4:26:44 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 282116
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
416 PM CDT WED MAY 28 2003

SYNOPTIC PICTURE THIS AFTERNOON SHOWS A SURFACE TROUGH EXTENDING
FROM AN ONTARIO LOW INTO CENTRAL ILLINOIS AND EASTERN MISSOURI.  A
STRONG PRESSURE GRADIENT BEHIND THIS TROUGH AND AHEAD OF INCOMING
HIGH PRESSURE CENTERED OVER NEBRASKA IS PRODUCING SUSTAINED WINDS
AT 20 TO 30 MPH WITH OCCASIONAL GUSTS TO 40 MPH.

THE PRIMARY FORECAST CONCERN OVER THE NEXT SEVEN DAYS IS A COLD
FRONT FRIDAY. ALSO OF INTEREST IS A TROUGH IN THE MONDAY NIGHT-
TUESDAY TIME FRAME.  THE MAIN CHARACTER OF THE WEATHER OVER THE NEXT
SEVERAL DAYS WILL BE COOLER THAN NORMAL TEMPS...AFTER TOMORROW...
ESPECIALLY IN THE SATURDAY THROUGH MONDAY TIME FRAME.  THE FORECAST
AREA WILL BE ON THE WESTERN EDGE OF A NORTHWEST FLOW REGIME THAT WILL
BE BRINGING UNSEASONABLY COOL WEATHER TO THE OHIO VALLEY.

THE SHORT-TERM MODELS AGREE ON THE WINDS DYING DOWN BY MID EVENING
AS THE TROUGH MOVES RAPIDLY EAST AND THE PRESSURE GRADIENT EASES.
THE MODELS ARE IN MODERATE AGREEMENT ON FRIDAY'S COLD FRONT...WITH
THE AVN AND UK BEING FASTER IN BRINGING THE FRONT THROUGH DVN THAN
THE ETA AND NGM...20Z VERSUS 16Z.  THIS DIFFERENCE IN TIMING COULD
BE CRITICAL...AS THE EARLIER TIMING WOULD RETARD CONVECTIVE
DEVELOPMENT UNTIL THE FRONT CROSSES THE MISSISSIPPI...SOMEWHAT
ANALOGOUS TO WHAT HAPPENED TODAY...WITH THE EXCEPTION THAT THIS
NEXT FRONT WILL BE STRONGER AND WILL BE FOLLOWED BY SIGNIFICANT
COLD AIR ADVECTION.  THAT HAVING BEEN SAID...IT LOOKS LIKE THE BEST
DYNAMICS MAY BE IN THE MORNING...WITH A BRIEF SHOT OF STRONG 700MB
VV'S AND 300MB DIVERGENCE...ALSO OUT OF SYNCH WITH DIURNAL HEATING
WHICH COULD PRODUCE CAPES UP TO 2000 IN ILLINOIS IN THE AFTERNOON...
MAINLY NEAR THE EXTREME EASTERN AND SOUTHEASTERN BOUNDARY OF THE
FORECAST AREA.

LOOKING FURTHER AHEAD...A SURFACE TROUGH IN THE MONDAY NIGHT-TUESDAY
TIME FRAME WILL PRODUCE THE NEXT CHANCE OF PRECIP.

WILL STAY CLOSE TO CURRENT FORECAST...EXCEPT WILL REMOVE CHANCE OF
PRECIP FRIDAY NIGHT AND SATURDAY MORNING NORTHEAST HALF.  DUE NOT
BELIEVE PVA IN THIS TIME PERIOD WILL BE SUFFICIENT TO PRODUCE
PRECIP.



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

$$

REA