[LeArc] Forecast Discussion : MLI@ 1/28/03 4:05:01 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 282215
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
414 PM CST TUE JAN 28 2003

SYNOPTIC PICTURE LATE THIS AFTERNOON SHOWS BROAD 500MB TROF OVER THE
EASTERN HALF OF THE COUNTRY WITH A RIDGE WEST...AND A SHORT WAVE
RIDING DOWN THE NORTHWEST FLOW OVER DVN.  AT THE SURFACE THE COLD
FRONT THE SWEPT THRU THE FORECAST AREA THIS MORNING EXTENDS FROM
SOUTHERN MISSOURI INTO CENTRAL ILLINOIS.  A BAND OF MODERATE SNOW
AND SLEET BEHIND THE FRONT IS PROGRESSING SOUTHWARD...WITH THE MAIN
BRUNT NOW MOVING SOUTH OF INTERSTATE 80.  FREEZING RAIN AT THE
ONSET OF THIS PRECIPITATION HAS CAUSING VERY SLIPPERY ROADS ACROSS
THE NORTHERN TWO THIRDS OF THE FORECAST AREA.

A WINTER WEATHER ADVISORY HAS BEEN EXTENDED TIL 7 PM FOR THE I-80
CORRIDOR...WHERE SNOW IS STILL FALLING ON SLICK ROADS.  FURTHER
SOUTH AN INCH OR SO OF SLEET AND SNOW IS EXPECTED.  LACK OF
SIGNIFICANT FREEZING RAIN SOUTH AT ONSET WILL PRECLUDE THE NECESSITY
OF AN ADVISORY.  UP TO AN ADDITIONAL INCH CAN BE EXPECTED SOUTH OF
INTERSTATE 80 THIS EVENING.

THE PRIMARY FORECAST CONCERNS THIS PACKAGE...OTHER THAN THIS
EVENING...ARE COLD FRONTS IN THE FRIDAY AND SUNDAY TIME FRAMES.
500MB FLOW WILL BECOME ZONAL OVER THE NEXT SEVERAL DAYS...WITH
DISTURBANCES EVERY OTHER DAY OR SO.  THIS WILL TEND TO MODERATE
TEMPERATURES. ON THE OTHER HAND...THE INCREASED SNOW COVER WILL
TEND TO SUPPRESS TEMPERATURES A CATEGORY OR TWO.

THE SHORT-TERM MODELS AGREE ON THE COLD FRONT MOVING WELL SOUTH OF
THE AREA THIS EVENING...WITH HIGH PRESSURE MOVING IN.  A HIGH WILL
MOVE OVERHEAD WEDNESDAY...AND SHIFT EAST ON THURSDAY AS WARM AIR
ADVECTION DEVELOPS.  THE MEDIUM-RANGE MODELS AGREE ON A COLD FRONT
FRIDAY...ACCOMPANIED BY A SHARP 500H TROF...AND A SECOND COLD FRONT
SUNDAY OR SUNDAY NIGHT...WITH THE MRF FAVORING SUNDAY EVENING AND THE
UK/EUROPEAN FAVORING MONDAY MORNING.

WILL STAY CLOSE TO CURRENT FORECAST.  THE REPLENISHED SNOW COVER
WILL AFFECT TEMPERATURES...IN A DOWNWARD DIRECTION...OVER THE NEXT
FEW DAYS. THE QUESTION THEN BECOMES WHETHER OR NOT OUR ADVERTISED
WARM-UP IN THE EXTENDED PERIOD WILL BE ENOUGH TO MELT SNOW.

.DVN...
IA...WINTER WEATHER ADVISORY TIL 7 PM FOR KEOKUK...WASHINGTON...
LOUISA...MUSCATINE...AND SCOTT COUNTIES.
IL...WINTER WEATHER ADVISORY TIL 7 PM FOR ROCK ISLAND...MERCER...
HENRY...BUREAU...AND PUTNAM COUNTIES.
MO...NONE.

REA

WWWW