[LeArc] Forecast Discussion : MLI@ 11/18/02 2:23:55 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 182035
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
235 PM CST MON NOV 18 2002

SYNOPTIC PICTURE THIS AFTERNOON SHOWS WEAKLY COUPLED 100KT JETS OVER
THE FORECAST AREA...WITH ONE JET OVER NORTHERN OKLAHOMA AND THE
OTHER OVER THE CENTRAL APPALACHIANS...CREATING MODERATE UPPER
DIVERGENCE AT 300MB. A STRONG 150KT JET WELL OFF THE WEST COAST...
RIDING UNDERNEATH A GULF OF ALASKA LOW...WILL BE A PLAYER IN THE
MIDWEST IN THE WEDNESDAY TIME FRAME.  AT 500H A SHARP SHORT...FROM
CENTRAL MINNESOTA TO EASTERN NEBRASKA...IS APPROACHING FROM THE WEST.
AT THE SURFACE A THROUGH EXTENDS FROM CENTRAL MINNESOTA THROUGH EAST
CENTRAL IOWA TO A LOW IN WEST CENTRAL MISSOURI...WITH A WEAK WARM
FRONT EXTENDING EAST FROM THIS LOW INTO SOUTH CENTRAL ILLINOIS.
ISENTROPIC LIFT PRODUCED LIGHT SPOTTY LIGHT RAIN FROM INTERSTATE 80
NORTH THIS MORNING...AND NOW UPPER DIVERGENCE IS AIDING IN BRINGING
IN MORE WIDESPREAD LIGHT RAIN THIS AFTERNOON.

THE PRIMARY FORECAST CONCERNS ARE THREE-FOLD.  FIRST IS THE TIMING
OF RAIN ENDING THIS EVENING.  PRECIP TYPE WILL NOT BE A PROBLEM
BECAUSE VERY BRIEF COLD SHOT AFTER TROF PASSAGE WILL BE AT 850MB
AND ABOVE...FOLLOWED BY WARM PLAINS TEMPS FOR TUESDAY.  SECOND
CONCERN IS PRECIP WEDNESDAY WITH ANOTHER SHARP SHORT WAVE...THIS ONE
FOLLOWED BY COLDER AIR FOR WEDNESDAY NIGHT...THURSDAY...AND FRIDAY.
THE THIRD CONCERN IS PRECIP IN THE SATURDAY/SATURDAY NIGHT TIME FRAME
WITH THE NEXT SYSTEM.

THE MODELS INITIALIZED WELL AT 500MB AND AT THE SURFACE...WITH THE
AVN DOING BEST AT 300MB WITH THE DOUBLE JET OVER THE CENTRAL U.S...
AND ALSO WITH THE 300MB JET OVER THE PACIFIC.

THE SHORT-TERM MODELS AGREE ON SURFACE TROF MOVING THRU DVN AROUND
00Z...WITH THE ACCOMPANYING SURFACE LOW MOVING SOUTH OF THE AREA
BETWEEN UIN AND STL.  THE 500H TROF AXIS WILL MOVE OVERHEAD AROUND
05Z.  THE NEXT SURFACE TROF WILL MOVE THROUGH DVN WEDNESDAY AROUND
21Z TO 00Z...WITH THE 500H TROF BETWEEN 00Z AND 06Z WEDNESDAY
EVENING. THE DVN FORECAST AREA WILL BE UNDER THE INFLUENCE OF THE
LEFT FRONT QUAD OF AN INCOMING 150KT JET ON WEDNESDAY FROM MIDDAY
INTO THE EVENING. THE MRF IS STILL INDICATING A COLD FRONT IN THE
SATURDAY/SATURDAY NIGHT TIME FRAME.

WILL STAY CLOSE TO CURRENT FORECAST...ADDING IN A CHANCE OF PRECIP
IN THE WEDNESDAY TIME FRAME...AT LEAST NORTHEAST.  WILL BUMP UP
MAXES FOR TUESDAY...AS WE GET WARM PLAINS DOWNSLOPE AIR.

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

REA