[LeArc] Forecast Discussion : MLI@ 9/22/02 1:43:01 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 221850
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
150 PM CDT SUN SEP 22 2002

.OVERVIEW...REINFORCING HIGH PRESSURE OVER KANSAS PRODUCING 15 TO 25+
MPH WINDS AND COOLER TEMPS.  SATELLITE SHOWS SOME FAIR WEATHER CUMULUS
CLOUDS WITH NEXT UPSTREAM SYSTEM IN WESTERN CANADA DIVING SOUTHEAST.
JET AXIS OF 100 TO 130+ KTS SUPPORTING VERY BAROCLINIC PATTERN WITH
TROUGH OVER MISSISSIPPI RIVER NOW MOVING EAST AT 15-20 MPH.  SOME CIRRUS
WITH CANADIAN UPSTREAM SYSTEM BUT LIMITED LOW LEVEL MOISTURE AND WITH
JET AXIS SLIDING BACK NORTH SUGGEST LITTLE CHANCE OF POPS WITH DRY
SURFACE DEWPOINTS.

...CHANCE OF FROST TONIGHT AND THEN TEMP CHANGES WITH NEXT DISTURBANCE
AND THEN POPS MIDWEEK WITH NEXT SYSTEM AND POTENTIAL IMPACT OF ISIDORE
AS IT MOVES NORTH INTO GULF COAST AREA.

.DIAGNOSIS AND DAYS 1-3...ALL MODELS TAKE NEXT SYSTEM NORTH OF AREA AND
WITH LITTLE MOISTURE...NO REASONABLE NEED FOR POPS BUT WILL SEE SOME MID
AND HIGH CLOUDS.  IDEAL RADIATIONAL COOLING TONIGHT WITH SFC RIDGE SO
WILL KEEP TEMPS 1-2 CATEGORIES BELOW MAV/FWC WITH UPSTREAM DEWPOINTS
~32-35F SO KEEP MENTION SOME SCATTERED FROST...ESPECIALLY WAPSI RIVER
BASIN INTO NW ILLINOIS.  SW WINDS BY MID DAY TO ALLOW NICE WARM UP 1-2
CATEGORIES ABOVE GUIDANCE BLEND AND PLAN FOR BREEZY PM CONDITIONS AHEAD
OF THIS NEXT SYSTEM.  TEMPS COOL EVEN MORE WITH THE NEXT REINFORCING
SHOT OF COOL AIR THROUGH TUESDAY MORNING WITH REASONABLE CHANCE OF FROST
AND MAYBE SOME FREEZING CONDITIONS. EXPECT AT LEAST A FROST ADVISORY
WILL BE NEEDED WITH THIS SYSTEM.  DRY AIR TO ALLOW TYPICAL EARLY FALL
RAPID WARMUP IN DAYTIME. FOR WEDNESDAY...GOOD WARMUP AND WILL GO 1-2
CATEGORIES ABOVE GUIDANCE WITH GOOD WAA AHEAD OF NEXT SYSTEM AND CHANCE
POPS LATE FOR NW AREAS WITH NEXT FRONT.

.EXTENDED...(THU-SUN)
LATEST MEDIUM RANGE MODELS CONTINUE TO SHOW STRONG...BUT SLOW MOVING
FRONT SLIDING IN FROM NORTHERN PLAINS WITH ISIDORE TO MOVE DUE NORTH
INTO LOWER CENTRAL MISSISSIPPI RIVER VALLEY BY THURSDAY WHICH SYNOPTIC
SCALE PATTERN SUPPORTS...SO HIGH CHANCE POPS NEEDED.  UNLIKELY ANY
MODEL HAS YET TO PROPERLY INCORPORATE JUST HOW ISIDORE AND WESTERN
TROUGH AND FRONT WILL PHASE TOGETHER AS ANTICIPATE NEED ANOTHER 24-36
HOURS TO DISCERN THIS. SO FOR NOW...WILL TREND TOWARD COOLING TREND AND
RAIN INTO EARLY FRIDAY AND COOL TEMPS FOR NEXT WEEKEND.

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

NICHOLS