[LeArc] Forecast Discussion : MLI@ 8/14/02 1:31:40 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 141834
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
130 PM CDT WED AUG 14 2002

.OVERVIEW...UPPER TROUGH HAS MOVED INTO EASTERN ILLINOIS WITH WEAK SFC
RIDGE BRINGING SEASONABLY COOL AIR WITH LOWER HUMIDITIES INTO REGION.
UPPER AIR SHOWS TROUGH SHEARING WITH NEXT UPSTREAM ENERGY MOVING INTO
NORTHERN PLAINS WITH LEE SIDE TROUGHING WELL UNDERWAY.  RIDGE AXIS NOW
NEAR I-380 CORRIDOR SO RETURN FLOW TO START BY EVENING MOST AREAS.
LIMITED SFC MOISTURE AND UPSTREAM TRIGGER FOR PRECIPITATION AS SUPPORTED
BY SATELLITE AND RADAR NEXT 24+ HOURS.  STRONG JET ALONG CANADIAN/US
BORDER PORTENDS CONTINUED CHANGEABLE PATTERN NEXT SEVERAL DAYS.

.DIAGNOSIS AND DAYS 1-3...SURFACE TEMPS SHOW ETA-2M AGAIN 3-6 DEGREES
TOO WARM HERE AND ALSO UPSTREAM.  OTHERWISE...BLEND MAV/FWC REASONABLE
WITH SOME INPUTS FROM PERSISTENCE...OR LOW SIDE FOR LOWS TONIGHT WITH
CLEAR SKIES AND THEN DECENT WARMUP TOMORROW AS SW WINDS OF 10-20KTS KICK
IN. WEAK FRONT ARRIVES LATE EVENING BUT LIMITED SFC MOISTURE AND UPPER
FORCING ALONG WITH DIFFUSE NATURE WILL PUT IN LOW CHANCE POPS AS DEPENDS
ON STRENGTH OF NOCTURNAL JET WHICH FOR NOW APPEARS MARGINAL. VERY WEAK
SURFACE HIGH FRIDAY SUGGEST MAX TEMPS ON HIGH SIDE OF MAV/FWC DUE TO
LIMITED COOLING.  MOST SIGNIFICANT FEATURE IS STRONGER UPSTREAM TROUGH
PRODUCING DECENT LOW LEVEL JET FRIDAY NIGHT AHEAD OF SEASONABLY STRONG
FRONT SO WILL GO ON WARM SIDE OF LOW TEMPS DUE TO GOOD WAA...SOME
CLOUDS AND DECENT MIXING.  FOR NOW NO COHERENT TRIGGER TIL FRONT ARRIVES
SO WILL HOLD OFF ON POPS TIL SATURDAY PM WITH HIGH CHANCE FOR NOW WITH
MODERATE RISK OF SOME SEVERE AND LOCALLY HEAVY RAINS INTO EVENING. LARGE
SCALE PATTERN SUGGEST SYSTEM TO BE AS STRONG IF NOT A TAD STRONGER AS
MONDAY SYSTEM SO RAISING POPS AND ADDING SEVERE/HEAVY RAIN WORDING MAY
BE NECESSARY NEXT FEW SHIFTS AS TIMING AND SMALLER SCALE FEATURES BECOME
MORE COHERENT. TEMPS ON SATURDAY WITH PRE-FRONTAL COMPRESSION AND GOOD
WAA AND SUNSHINE WILL GO 1-2 CATEGORIES ABOVE GUIDANCE AS NORMAL WITH
DECENT FROPA.

.EXTENDED (SUN-WED)...MODELS SIMILAR ON SUN/MON FOR COOL DOWN SUNDAY
AS NEXT SURFACE HIGH MOVES IN.  THEN...AS WARM FRONT APPROACHES POPS
STILL REASONABLE MONDAY INTO EARLY TUESDAY.  WARM AND HUMID CONDITIONS
FOR LATE TUE/WED AHEAD OF NEXT SYSTEM.

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

NICHOLS