[LeArc] Forecast Discussion : MLI@ 9/24/02 3:02:03 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 242010
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
305 PM CDT TUE SEP 24 2002

ISENTROPIC ANALYSIS AND FORECAST SOUNDINGS SUGGEST ENOUGH LIFT AND
COLUMN SATURATION ON EDGE OF ELEVATED WAA...TO BRING MID DECK ACRS AT
LEAST NORTHERN THIRD OF CWA LATER TONIGHT. VIRGA AND SPRINKLES MAY
TRY TO SPREAD EAST OUT OF NORTH CENTRAL IA...BUT SHOULDN'T BE A
ENOUGH OF A FACTOR WORTHY OF ZONE MENTION. MUCH OF IT SHOULD DRY UP
AS IT HEADS EAST ANYWAY. WITH SOME CLOUD COVER AND ENOUGH OF SFC
GRADIENT TO THE WEST OF RIDGE AXIS FOR A LIGHT SOUTHEAST BREEZE...
TEMPS WILL BE MILDER TONIGHT THAN LAST NIGHTS BOTTOM OUT. STILL...
ACRS EAST CENTRAL AND SOUTHEAST CWA CLOSER TO RIDGE CENTER INFLUENCE
AND CLEARER SKIES...FEEL TEMPS WILL DIP BELOW GUIDANCE...ESPECIALLY
WITH A QUICK SLIDE AFTER SUNSET WITH WINDS STILL LIGHT AND VARIABLE.
WOULDN'T BE SURPRISED FOR A FEW UPPER 30S ACRS FAR EAST.

LINGERING WAA CLOUDS SHOULD DIMINISH ON WED FOR MOSTLY SUNNY
AFTERNOON. FORECAST SOUNDINGS SUGGEST FULL MIXING POTENTIAL WON'T BE
REACHED...OTHERWISE TEMPS COULD REACH THE 80S. EVEN LIMITED MIXING
SUPPORT UPPER 70S WITH INSOLATION...WITH SOUTH WINDS GETTING TOWARD
BREEZY CONDITIONS 15-20 MPH SUSTAINED. BUT EXTRAPOLATING CURRENT
TEMPS IN PORTION OF WESTERN RIDGE GRADIENT AXIS THAT WILL BE ACRS THE
CWA TOMORROW/NORTHEAST KS/...TEMPS HAVING TROUBLE REACHING MID 70S.
BUT UPPER 70S AND LOWER 80S NOT THAT MUCH FARTHER WEST...AND WILL
PLAY COOLER EAST-TO-WARMER WEST ZONE GROUPING AND INCORPORATE UPPER
70S ACRS SOUTHWEST HALF.

MODELS CONTINUE TO SLOW FROPA OF NEXT MAIN SFC BOUNDARY ACRS THE CWA
THU MORNING WITH ISIDORE INFLUENCE. IN DRY AIRMASS...LLVL FORCING
AND ISENTROPICS OVER FRONT CREATING SHRIVELING POST-FRONTAL PRECIP
PATTERN. MODELS NOW BARELY MAKE DECAYING RAIN/SPRINKLES ACRS THE CWA
FROM 18Z THU-06Z FRI...AS ISIDORE MAKES AS A MOISTURE HOG ACRS MOUTH
OF THE MISSISSIPPI. WILL PLAY DOWN CHANCES AND ADJUST LIMITED PRECIP
THREAT FOR THU AND THU NIGHT. THU HIGHS RANGING FROM LOWER TO UPPER
60S...FROM NORTHWEST TO SOUTHEAST.

.LONGER RANGE(FRI-TUE)...MEDIUM RANGE MODEL ENSEMBLE GENERALLY SWEEPS
ISIDORE REMNANTS TOWARD EASTERN TN/KY THROUGH SAT MORNING...AS
DIGGING WAVE DROPS ACRS THE NORTHERN ROCKIES. MRF QUICKEST TO DO
THIS....WHILE LATEST UKMET/ECMWF STILL HAS TROPICAL STORM SPIRALING
OVER NORTHERN MS/AL/TN REGION AT 12Z SAT...BEFORE RACING DECAYING
STORM UP THE APPALACHIANS. IN ANY CASE...THIS STORM DOES NOT LOOK
LIKE IT WILL BECOME A FACTOR TO LOCAL AREA BESIDES POSSIBLY WHIRLING
SOME HIGH CLOUDS ACRS SOUTHEAST CWA FRI AFTERNOON. INCOMING RIDGE AT
SFC TO BE IMPLANTED ACRS UPPER MS RVR VALLEY AND WESTERN GRT LKS FOR
WEEKEND...MAYBE. INTERESTING DIFFERENCES HERE FROM UKMET/MRF WHICH
ARE SIMILAR...AND THE EURO. THE UKMET/MRF MAINTAINS SFC RIDGE AXIS
ACRS EAST NE...TO LOWER MI THROUGH SUNDAY...SETTING UP BAROCLINIC
ZONE JUST TO THE SOUTH. VIGOROUS WAVE TO THEN DROP SOUTHEAST ACRS THE
AREA GENERALLY AROUND SAT NIGHT...WITH ENOUGH FORCING AND ADJACENT
BAROCLINICITY TO PRODUCE A LIGHT OVER-RUNNING PRECIP EVENT SAT NIGHT
AND POSSIBLY INTO SUNDAY. UKMET HAS TRENDED SLOWER WITH WAVE AND
WOULD LINGER LIGHT RAIN INTO SUNDAY AFTERNOON...WHILE MRF WOULD END
IT BY NOON. THE WORLD ACCORDING TO THE ECMWF WOULD DUMP SFC RIDGE
FURTHER WEST AND SOUTH INTO SOUTHERN PLAINS...ARCHING BAROCLINIC
HIGHWAY UP THROUGH THE CWA. THE EURO ALSO DEVELOPS STRONGER SFC WAVE
WHICH WOULD RIPPLE UP ALONG LEE SIDE OF RIDGE AXIS TO THE WEST FOR
MORE OF A SIGNIFICANT PRECIP EVENT SAT NIGHT AND SUNDAY FOR THE CWA.
WILL SIDE WITH UKMET...LEAVING OUT PRECIP MENTION FOR DAYTIME SAT FOR
NOW...AND INTRODUCE LIGHT RAIN FOR SUN. ANY CHANGES IN WAVE TIMING IN
FUTURE MODEL RUNS WILL MEAN ADJUSTMENT FOR WEEKEND OUTLOOK. WITH
CLOUDS AND LIGHT RAIN...HIGHS MAY STRUGGLE ON SUNDAY TO REACH UPPER
50S. WILL SLOW TEMP MODERATING TREND INTO EARLY NEXT WEEK...WITH 70S
NOT TO RETURN TIL NEXT TUESDAY.


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

JDH