[LeArc] Forecast Discussion : MLI@ 2/19/03 4:02:48 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 192207
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
407 PM CST WED FEB 19 2003

SYNOPTIC PICTURE THIS AFTERNOON SHOWS BROAD 500H TROF OVER EASTERN
HALF OF COUNTRY...A RIDGE WEST...AND A SHARP TROF DIGGING ONTO THE
WEST COAST.  AT THE SURFACE...HIGH PRESSURE IS CENTERED OVER
SOUTHWEST IOWA...WITH A TROF EXTENDING FROM AN ALBERTA LOW INTO
WESTERN NEBRASKA.  SKIES ARE SUNNY AND TEMPERATURES THIS AFTERNOON
ROSE TO AROUND 40...EXCEPT A FEW DEGREES COOLER OVER THE SNOW FIELD.
SIGNIFICANT MELTING OCCURRED ON THE FRINGES OF THE SNOW...BUT THE
FIELD IS STILL MODERATELY INTACT IN MOST AREAS SOUTH OF INTERSTATE 80
IN ILLINOIS...AND SOUTH OF A CEDAR RAPIDS TO MUSCATINE LINE IN IOWA.

THE PRIMARY FORECAST CONCERNS THIS PACKAGE ARE WEAK NORTHERN
STREAM WAVES THURSDAY AND FRIDAY...AND A STRONGER SOUTHERN
STREAM STORM FRIDAY NIGHT AND SATURDAY.  ALSO OF SIGNIFICANCE IS
500H TROFING IN THE SUNDAY-MONDAY TIME FRAME.  PRIMARY SIGNAL THE
NEXT SEVERAL DAYS IS MAINLY ZONAL FLOW WITH MODERATE TEMPERATURES
THROUGH FRIDAY...WITH SATURDAY BEING A TRANSITION DAY...AND SUNDAY
BACK DOWN INTO WINTER.  SIGNIFICANT PRECIP WILL BE HARD TO COME BY
OVER THE NEXT 7 DAYS.

THE SHORT TERM MODELS AGREE ON SHORT WAVES THURSDAY AND FRIDAY
BEING OF NO CONSEQUENCE...EXCEPT PULLING SLIGHTLY COOLER AIR INTO
THE AREA FOR FRIDAY.  SIGNIFICANTLY COLDER AIR WILL BEGIN COMING ON
THE BACKSIDE OF THE SOUTHERN STORM ON SATURDAY.  THE AVN...ETA...
AND MEDIUM-RANGE MODELS AGREE ON THIS STORM LIFTING INTO THE CENTRAL
APPALACHIANS ON SATURDAY...WITH SIGNIFICANT...POSSIBLY EXPLOSIVE...
DEEPENING.  THIS WILL PRODUCE CLOUDS AND A CHANCE OF LIGHT RAIN OR
SNOW SATURDAY...AND A CHANCE OF LIGHT SNOW SATURDAY NIGHT. OF MORE
INTEREST IS A SECONDARY LOW...FOLLOWING ON THE TRAIL OF THE MAIN
ONE..THAT WILL MOVE OUT OF THE SOUTHERN PLAINS AND ALONG THE
MISSOURI-ARKANSAS LINE SUNDAY...WITH A SHARP INVERTED TROF OVER OUR
FORECAST AREA. A STRONG TRAILING 500H TROF SWINGS THRU THE AREA
BEHIND THIS SYSTEM ON MONDAY. THE DYNAMICS MAY BE MODERATE SUNDAY
AND MONDAY...BUT MOISTURE...IN THE WAKE OF THE PRIMARY LOW MAY BE
LIMITED.

WILL STAY WITH THE CURRENT FORECAST FOR ABOVE GUIDANCE TEMPS ON
THURSDAY.  WILL ALSO INTRODUCE A CHANCE OF SNOW MONDAY. OTHERWISE
LITTLE CHANGE IN THE FORECAST.

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

$$

REA