[LeArc] Forecast Discussion : MLI@ 3/4/03 5:08:27 PM

Tue, 04 Mar 2003 17:08:27 -0600

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

FXUS63 KDVN 042318
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
517 PM CST TUE MAR 4 2003

THE SYNOPTIC PICTURE LATE THIS AFTERNOON SHOWS NEAR ZONAL FLOW AT
500MB ACROSS THE MID-SECTION OF THE COUNTRY...WITH A TROF EXTENDING
FROM THE CANADIAN PLAINS INTO THE NORTHERN ROCKIES.  AT THE
SURFACE...THE COLD FRONT THAT MOVED THRU OUR AREA LAST NIGHT
EXTENDS FROM A 995MB LOW IN SOUTHWEST OKLAHOMA THRU NORTHERN
MISSOURI INTO CENTRAL ILLINOIS. MOISTURE OVERRUNNING THE RECEDING
FRONT...COMBINED WITH STRONG UPPER-LEVEL DIVERGENCE IN THE
REAR ENTRANCE REGION OF A 150KT JET OVER THE GREAT LAKES...IS
PRODUCING EXTENSIVE HEAVY SNOW ACROSS THE REGION...WITH 2 TO 3
INCHES ALREADY IN NORTHWEST PORTIONS OF THE FORECAST AREA.
ISENTROPIC UPSLOPE IS ALSO PROVIDING LIFT FOR SNOW.

THE PRIMARY FORECAST CONCERN THIS AFTERNOON IS IN THE NEAR TERM...
WITH THE ONGOING WINTER STORM.

THE SHORT-TERM MODELS AGREE ON A SURFACE WAVE MOVING FROM SOUTHWEST
TO NORTHEAST ALONG THE FRONT OVERNIGHT...PASSING SOUTH OF UIN IN
THE 06Z TIME FRAME.  UPPER SUPPORT WILL QUIT RATHER SHARPLY FROM
NORTHWEST TO SOUTHEAST AFTER THIS...WITH FLURRIES FINISHING OFF THE
NIGHT.  THE MODELS ARE CONSISTENT WITH A MAX QPF AXIS OF 0.5 TO 0.6
INCHES ACROSS THE FORECAST AREA FROM SIGOURNEY TO THE QUAD CITIES...
WITH 0.3 TO 0.4 INCHES FAR NORTH...AND FAR SOUTH.  CONDITIONS ARE
FAVORABLE FOR DENDRITIC SNOW...WITH COLD SURFACE TEMPERATURES IN THE
TEENS...STRONG VV'S AND FAVORABLE -13 TO -17 TEMPS BETWEEN 700MB
AND 600MB.  WINDS WILL BE OUT OF THE NORTH AT 15 TO 25 MPH...
PRODUCING BLOWING AND DRIFTING SNOW.  DRIFTING WILL BE ESPECIALLY
PREVALENT ON EAST-WEST ORIENTED ROADWAYS.

LOOKING FURTHER AHEAD...HIGH PRESSURE WILL BUILD OVER THE AREA
WEDNESDAY...AND MOVE EAST THURSDAY AS ANOTHER COLD FRONT APPROACHES
FROM THE WEST. THE AVN...ETA...AND MEDIUM-RANGE MODELS AGREE ON
THE FRONT MOVING THROUGH ON FRIDAY...WITH CHANCE POPS.  AFTER THAT...
THE NEXT FRONT IS IN THE TUESDAY TIME FRAME.

STAYED CLOSE TO CURRENT FORECAST...FAVORING TEMPS BELOW GUIDANCE DUE
TO NEW SNOW COVER.

THANKS TO DMX...LOT...ILX...ARX FOR COORDINATION.

.DVN...
IA...WINTER STORM WARNING TONIGHT.
IL...WINTER STORM WARNING TONIGHT.
MO...WINTER STORM WARNING TONIGHT.

$$

REA