[LeArc] Forecast Discussion : MLI@ 9/19/02 2:24:09 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 190731
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
230 AM CDT THU SEP 19 2002

SYNOPTIC PICTURE THIS MORNING SHOWS FULL LATITUDE 500H TROF FROM
NEW MEXICO TO THE EASTERN DAKOTAS...WITH CLOSED LOW OVER NORTHERN NM.
AT THE SURFACE A COLD FRONT EXTENDS FROM CENTRAL OKLAHOMA THRU WESTERN
IOWA INTO WESTERN MINNESOTA...WITH LOWS ALONG THE FRONT IN OKLAHOMA AND
WESTERN MINNESOTA...AND A HINT OF A LOW IN SOUTH CENTRAL IOWA.
WIDESPREAD CONVECTION THRU EASTERN IOWA INTO SOUTHERN WISCONSIN IS ON
NOSE OF LOW-LEVEL JET...WITH UPPER SUPPORT FROM 100KT JET STREAK. PRECIP
EXTENDS ALONG AXIS OF LLJ SOUTHWEST TO THE OKLAHOMA LOW.

THE PRIMARY FORECAST CONCERN THIS PACKAGE IS PRECIPITATION TODAY...
TONIGHT...AND FRIDAY. THERE ARE SIGNIFICANT DIFFERENCES IN SHORT-RANGE
MODELS IN HANDLING OF THIS EVENT.  THE NGM AND ETA HAVE HANDLED THE COLD
FRONT BEST THRU 06Z...ESPECIALLY WITH REGARD TO OKLAHOMA LOW...WHICH
COULD BE A PLAYER IN OUR WEATHER IN THE NEXT 24 HOURS.  THE ETA HAS
DONE BEST THRU 06Z WITH QPF.

THE AVN BRINGS THE COLD FRONT THRU DVN THURSDAY EVENING...WITH A WAVE
LIFTING NORTH ALONG THE FRONT DURING THE DAY TODAY...AND BRINGS A
SECONDARY FRONT THRU SATURDAY MORNING.  THE ETA HANGS THE COLD FRONT
UP IN EASTERN IOWA THRU TONIGHT AND FRIDAY...AND THEN KICKS IT
EAST FRIDAY EVENING...TIMING A SHORT WAVE NORTH ALONG THE FRONT IN THE
TONIGHT AND FRIDAY MORNING TIME FRAME.  THE NGM IS A MIX OF THE TWO...
BUT IS CLOSER TO THE ETA.  AT 500H THE AVN BRINGS THE PRIMARY TROF AXIS
OVER DVN FRIDAY EVENING...WITH A SECONDARY TROF ON SUNDAY.  THE ETA AND
NGM ARE NOT TOO FAR OFF OF THIS TIMING...PERHAPS A FEW HOURS SLOWER.
THE MODELS AGREE MODERATELY WELL ON VV'S THIS AFTERNOON AND EVENING...
WITH 250MB DIVERGENCE THRU 06Z TONIGHT.  AFTER 06Z TONIGHT...THE
DYNAMICS BEGIN SHIFTING EAST...AND MAIN PRECIP AXIS LATE TONIGHT...
FRIDAY...AND FRIDAY IS EAST INTO CENTRAL ILLINOIS.

WILL LEAN TOWARDS ETA/NGM SOLUTION...WHICH HANGS ONTO PRECIP LONGER
THAN AVN. THIS AGREES PRETTY WELL WITH OUR ONGOING FORECAST. WILL BE
TWO COLD PUNCHES...THE FIRST TONIGHT INTO FRIDAY...AND THE SECOND LATE
FRIDAY NIGHT AND SATURDAY.  WILL STAY CLOSE TO CURRENT TEMP FORECASTS...
PER SLIGHTLY SLOWER COOLING TREND...BUT MAY LOWER TEMPS INTO EARLY
NEXT WEEK PER PEAK AT NEW FMR/MEX.

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

REA