[LeArc] Forecast Discussion : MLI@ 11/19/02 2:32:47 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 192044
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
244 PM CST TUE NOV 19 2002

SYNOPTIC PICTURE THIS AFTERNOON SHOWS AMPLIFIED PATTERN AT 300MB...
WITH A TROF FROM CENTRAL ONTARIO INTO THE LOWER MISSISSIPPI VALLEY
WITH TWO SPOKES...THE FIRST INTO THE OHIO VALLEY AND THE SECOND INTO
THE SOUTHERN PLAINS.  TO THE WEST A SHARP RIDGE IS ALONG THE WEST
COAST.  A 160KT JET RIDING UP OFF THE PACIFIC OVER THIS RIDGE WILL
BE A WEATHER MAKER FOR OUR AREA WEDNESDAY AND THURSDAY.  THE 500H
PATTERN IS SIMILAR...WITH A VORT MAX OVER NORTH CENTRAL KANSAS AND
ANOTHER OVER NORTH DAKOTA.  AT THE SURFACE A TROF ASSOCIATED WITH
THE WESTERN SPOKE OF THE UPPER TROF EXTENDS FROM A LAKE SUPERIOR LOW
INTO CENTRAL IOWA.

THE PRIMARY FORECAST CONCERN IS THE STRONG JET ENERGY THAT WILL
ROUND THE TOP OF THE RIDGE TONIGHT AND DIVE IN CENTRAL IOWA ON
WEDNESDAY...BRINGING A CHANCE OF RAIN...WITH SNOW POSSIBLE
WEDNESDAY NIGHT INTO THURSDAY.

THE SHORT-TERM MODELS AGREE ON BRINGING A LEADING VORT MAX THRU THE
FORECAST AREA BETWEEN 09Z TONIGHT AND 18Z WEDNESDAY...WITH A SURFACE
TROF BETWEEN 12Z AND 15Z. BUT LITTLE MOISTURE TO WORK WITH. UPPER
DIVERGENCE ASSOCIATED WITH THE JET COMES INTO PLAY DURING THE DAY AND
CONTINUES THRU WEDNESDAY NIGHT.  THE 500H TROF MOVES IN OFF THE
PLAINS AND OVER DVN AROUND 18Z...WITH THE TROF DEEPENING DRAMATICALLY
THRU THURSDAY AND INTO THURSDAY NIGHT AS IT SHIFTS SLOWLY EAST.  A
SURFACE TROF SWINGS THRU WEDNESDAY NIGHT...AROUND 06Z...WITH COLD
AIR ADVECTION BEGINNING IN EARNEST AND CONTINUING THRU FRIDAY
NIGHT.  1000-500 AND 1000-850 THICKNESSES DROP QUICKLY BELOW 540 AND
1312 RESPECTIVELY WEDNESDAY NIGHT.  THE TRACK OF A STRONG VORT MAX
WEDNESDAY NIGHT/THURSDAY MORNING WILL BE KEY AS TO SNOW POTENTIAL.
SOME DISAGREEMENT IN MODELS ON TRACK BUT NORTHERN COUNTIES WILL BE
FAVORED FOR AT LEAST SOME MEASURABLE SNOW WEDNESDAY NIGHT AND
THURSDAY MORNING...TAPERING TO FLURRIES THURSDAY.

WILL DEFOCUS THE TIMING FOR RAIN ON WEDNESDAY...AS COULD BE MORNING
OR AFTERNOON. WILL MENTION CHANCE OVER TO SNOW WEDNESDAY NIGHT AND
KEEP A CHANCE OF SNOW EARLY THURSDAY...TAPERING TO FLURRIES.
LOOKING FURTHER AHEAD MEDIUM-RANGE MODELS AGREE ON THE NEXT COLD
FRONT SATURDAY AFTERNOON OR EVENING...WITH COLD AIR ADVECTION
SUNDAY AND MONDAY.  MAY LOWER TEMPS A NOTCH IN LATER DAYS OF THE
FORECAST.

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

REA