[LeArc] Forecast Discussion : MLI@ 10/22/02 2:42:49 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 220751
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
250 AM CDT TUE OCT 22 2002

SYNOPTIC SCALE THIS MORNING SHOWS RIGHT REAR QUAD OF 95KT JET OVER
SOUTH DAKOTA.  AT 500H...A SHARP TROF EXTENDS FROM A NOVA SCOTIA LOW
ALONG THE U.S.-CANADIAN BORDER INTO NORTHERN MONTANA.  AT THE SURFACE A
LARGE HIGH IS CENTERED OVER SASKATCHEWAN...EXTENDING SOUTHEAST INTO
NEBRASKA AND IOWA.  SNOW IS FALLING OVER NORTHERN SOUTH DAKOTA IN
RESPONSE TO NORTHERN 500H TROF AND JET SUPPORT.

PRIMARY FORECAST CONCERNS THIS PACKAGE ARE FOR PRECIP CHANCES TODAY...
WEDNESDAY...THURSDAY...AND INTO FRIDAY...AS SURFACE HIGH DIGS INTO
HIGH PLAINS...PRODUCING TROFING INTO THE MISSISSIPPI VALLEY. PRECIP
TYPE WILL BE AN ISSUE...ESPECIALLY NORTH OF INTERSTATE 80.

IN THE SHORT TERM THE SOUTH DAKOTA PRECIP WILL WORK EAST TODAY...
PERHAPS PRODUCING A FEW SPRINKLES NORTH THIS AFTERNOON. THE SURFACE LOW
WILL BUILD SOUTH INTO THE PLAINS THRU 48 HOURS...WITH SIGNIFICANT
DIFFERENCES BETWEEN MODEL SOLUTIONS.  THE AVN DIVES THE COLDER
STRAIGHT SOUTH INTO THE HIGH PLAINS...WITH TROFING DEVELOPING IN THE
MISSISSIPPI VALLEY THURSDAY.  THE ETA AND NGM BRING THE SURFACE HIGH
FURTHER EAST INTO THE LOWER PLAINS...SUPPRESSING ANY TROFING THRU 72
HOURS SOUTH OF THE FORECAST AREA.  THE CANADIAN IS IN BETWEEN...WITH
SLOWER TIMING...LIFTING A WAVE THRU CENTRAL ILLINOIS IN THE FRIDAY TIME
FRAME.  THE MAIN FORCING THRU THIS PERIOD WILL BE FROM THE JET LEVEL
WITH THE RIGHT REAR QUAD OF A 110KT NORTHERN TIER JET OVER THE FORECAST
AREA WEDNESDAY AND WEDNESDAY NIGHT.  A SOUTHERN 90KT BRANCH OF THE
JET WILL BE JUST SOUTHEAST OF THE FORECAST AREA FRIDAY.  VV'S WILL BE
MODERATE WEDNESDAY AND WEDNESDAY NIGHT...BUT ISENTROPIC LIFT WILL NOT
BE A SIGNIFICANT FACTOR.  1000-500MB AND PARTIAL THICKNESSES ARE
MARGINAL FOR NORTHERN SECTIONS THRU THE NEXT 72 HOURS...ESPECIALLY
DURING THE LATE NIGHT AND MORNING HOURS.

LOOKING FURTHER AHEAD...NEW MRF RUN INDICATES A STRONG 500H WAVE IN
THE MONDAY TIME FRAME.

CURRENT FORECAST IS ON TRACK.  WILL MAKE ONLY MINOR ADJUSTMENTS.

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

REA