[LeArc] Forecast Discussion : MLI@ 5/25/2003 1:51:46 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 251850
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
145 PM CDT SUN MAY 25 2003

.OVERVIEW...PERSISTENT MILD NORTHEAST FLOW WITH TEMPERATURES NOW INTO
THE LOWER 70S AS OF 18Z UNDER FULL SUNSHINE. SOME CUMULUS NOW FORMING
WITH HEATING.  EVIDENCE OF LAKE MICHIGAN ENHANCED BOUNDARY NOW FROM
NEAR AURORA TO JUST EAST OF MADISON A BIT MORE VIGOROUS THAN PAST 2
DAYS.  UPPER AIR ANALYSIS SUPPORTS LITTLE CHANGE IN PATTERN BESIDES SLOW
MODIFICATION OF AIRMASS WITH STRONG LATE MAY SUNSHINE.

...TEMPERATURES AND AMOUNTS OF CLOUDS REMAIN FORECAST ISSUE THROUGH
EARLY WEDNESDAY...THEN INCREASING CHANCE OF STORMS...

.DIAGNOSIS...DAYS (1-3)...PERSISTENCE BEST TOOL AS NO SIGNIFICANT CHANGE
IN PATTERN NEXT TWO DAYS EXCEPT FOR GRADUAL MODIFICATION OF AIRMASS WITH
RISING TEMPS AND DEWPOINTS A FEW DEGREES A DAY.  THIS SUGGESTS SOME
ISOLATED SHOWERS ALONG LAKE BOUNDARY FORMING ABOUT 4-5PM ALONG I-55 IN
ILLINOIS TOMORROW THAT MAY MIGRATE INTO FAR EAST SECTIONS TOWARD SUNSET.
TUESDAY...AN EVEN BETTER CHANCE ALONG BOUNDARY...BUT AGAIN PASS TO LATER
SHIFTS.   A DIFFERENCE OF A FEW DEGREES WILL RESULT IN EITHER JUST A
LINE OF HEAVY CUMULUS VERSUS A BROKEN LINE OF LIGHT TO BRIEFLY MODERATE
STRENGTH SHOWERS THAT COULD DROP A TENTH OF AN INCH OR SO OF RAIN TIL
SUNSET.  TEMPERATURES WILL GO A CATEGORY BELOW NEXT 2 DAYS FOR LOWS AND
NEAR TO SLIGHTLY ABOVE FOR MAX TEMPS INTO WEDNESDAY...OR PERSISTENCE.
NEXT DISTURBANCE FROM NW ARRIVES LATE PM AND EVENING WITH SFC DEWPOINTS
REBOUNDING TO AROUND 60. THIS WILL CAUSE LOW END OF MODERATE STRENGTH
INSTABILITY BY AFTERNOON AND COMBINED WITH MODERATE TO WEAK FORCING WILL
LIKELY TRIGGER SOME STORMS AND SHOWERS BUT SCALE OF THIS EVENT WILL TAKE
AT LEAST ANOTHER 24-36 HOURS TO BETTER RESOLVE TOWARD MORE SPECIFICS.
APPEARS ONLY A SLIGHT RISK OF SOME STORMS REACHING MARGINAL SEVERE
STRENGTH...BUT AGAIN...KNOW BETTER BY TUESDAY.

.EXTENDED (THU-SUN)...MODERATE VARIANCE IN MODEL SOLUTIONS REMAINS FOR
FRIDAY INTO SATURDAY SYSTEM WITH STRENGTH AND TO LESSER EXTENT TIMING
ISSUES.  LITTLE REASON TO CHANGE CURRENT PACKAGE OF CHANCE POPS BOTH
DAYS.  LATE SPRING CONVECTIVE PATTERN STILL REASONABLE FRIDAY INTO
SATURDAY FOR MCS EVENT(S) AHEAD OF OR WITH THIS NEXT COLD FRONT.
SHEAR...ESPECIALLY MOISTURE AND FORCING CONTINUE TO SUGGEST SOME BOWING
SEGMENTS...POSSIBLY MCC/DERECHO DEPENDING ON TIMING AND EVOLUTION STAGE
OF STORMS.  BETTER CLARITY SHOULD BE EVIDENT BY MONDAY PM...CURRENT BEST
ESTIMATE IS SOME SEVERE WEATHER TO OCCUR WITH LATE WEEK COLD FRONT.

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

$$

NICHOLS