[LeArc] Forecast Discussion : MLI@ 5/24/02 2:15:46 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 241914
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
210 PM CDT FRI MAY 24 2002

LEAD VORT SEEN ON W/V IMAGERY OVER SOUTHEAST NE AND NORTHEAST KS...
ASSOCIATED WITH DECAYING MCS IN THAT VCNTY...WILL CONTINUE TO PULL
ACRS CENTRAL IA THIS EVENING. WILL WATCH INCOMING PRECIP TRENDS...BUT
EXPECT DECAYING SYSTEM TO BRING CHANCE TO MUCH OF CWA BY MID TO LATE
EVENING. SECONDARY BUT MORE VIGOROUS VORT ALREADY FORMING NEXT MCS
OVER CO...WILL FOLLOW QUICKLY ON HEELS OF THIS EVENINGS WAVE AND ROLL
ACRS IA THROUGH SAT MORNING. VARIOUS VORT PATH ENSEMBLE SUPPORTS
MIDDLE OF ROAD UKMET PATH ALONG H85 BAROCLINIC HIGHWAY ACRS WEST
CENTRAL AND THEN NORTHERN PORTION OF CWA BY LATE TONIGHT/EARLY SAT
MORNING...WITH SFC LOW PATH TO THE SOUTH ACRS NORTHERN MO AND
CLIPPING SOUTHEAST CWA BY 12Z SAT. VORT TO INDUCE IMPRESSIVE BOUT OF
POS OMEGAS RIGHT OVER THE CWA AROUND 12Z SAT...AND COMBINE CONCEPTUAL
MODEL IDEA WITH VORT PATH...LOOKS LIKE HEAVIER PRECIP THREAT ACTUALLY
TO BE ACRS THE NORTH HALF OF THE CWA...ALONG AND NORTH OF THE I-80
CORRIDOR. INHERENT ENHANCED LLVL CONVERGENCE ALONG INVERTED TROUGH
AND TO LEE SIDE OF MAIN SOUTHWARD SFC COLD POOL SEEPAGE TO NORTHWEST
OF SYSTEM ALSO SUPPORTS HEAVIER PRECIP PLACEMENT ACRS THE NORTH HALF.
FEEL BULK OF DEF ZONE PRECIP WITH SECONDARY/MAIN SYSTEM TO FALL ACRS
THE LOCAL CWA FROM 07Z TO 14Z SAT...WITH EXTENT OF PW'S AND OMEGAS
SUPPORTING WIDESPREAD HALF TO 1 INCH TOTALS BY MID SAT MORNING. WILL
NOT GO WITH FLOOD WATCH HEADLINES FOR TONIGHT...AS ABOVE ARGUMENT
SUGGESTS HEAVY PRECIP BANDS WILL OCCUR FURTHER TO NORTH OF SATURATED
AREA OF CONCERN ACRS NORTHEAST MO...SOUTHEAST IA...AND WEST CENTRAL
IL. THE COUNTIES OF HENRY IL...BUREAU AND PUTNAM HAVE LOWER FFG
GUIDANCE AND MAY BE ON FENCE OF HEAVIER RAINFALL. WILL LET SHORT TERM
ADVISORIES OR WARNINGS COVER ANY WATER TROUBLE THAT MAY OCCUR IN THIS
LIMITED CWA COVERAGE LATE TONIGHT OR SAT MORNING.

WITH COOL AND DRY NORTHEAST FLOW OUT OF WI...INCOMING ACTIVITY WILL
HAVE TO OVER-RIDE IT. THUS ACTIVITY MAY BE MORE OF AN OVER-RUNNING
RAIN EVENT WITH SOME EMBEDDED THUNDER. FCST SOUNDINGS SHOW ELEVATED
INSTABILITY MARGINAL BY LATE TONIGHT FOR THUNDER...BUT EXTENT OF POS
OMEGAS WILL MAKE UP FOR IT...AT LEAST ACRS THE SOUTH HALF OF THE CWA.
WITH COOL SFC INFLUX FROM NORTHEAST OF LOW WET BULB ZERO AIRMASS/LOW
DPTS...ANY PRECIP INTO IT WILL SUPPORT COOLER MAV LOWS FOR TONIGHT...
AND MAY EVEN UNDERCUT THOSE VALUES ACRS THE EAST.

LINGERING RAIN WILL TAPER OFF AND SHOULD END AROUND NOON ACRS THE
EAST. SFC WINDS SWINGING AROUND TO THE WEST-NORTHWEST...AND SOME
DECREASE IN CLOUDS WILL MAKE FOR A LATE AFTERNOON AND EVENING HIGH
TEMPERATURE FOR THE DAY...BUT MAV AND FWC STILL LOOK A TAD WARM. MOST
OF CWA MAY BE IN MID 60S RANGE FOR SAT HIGHS...WITH COOLEST READINGS
IN SOUTHEAST CWA/WEST CENTRAL IL WHERE AFTERNOON CLEAR OUT
QUESTIONABLE AND LAST AREA FOR PRECIP TO END...FOR LINGERING WET
GROUND THERMAL ABSORPTION EFFECT.

SOUTHWEST RETURN FLOW TO MAKE FOR GOOD WARM-UP ON SUNDAY...WITH
PROGGED H85 TEMPS AND INSOLATIVE DRIVEN MIXING SUPPORTING AT LEAST
UPPER 70S...EVEN AN 80. NEXT BOUNDARY SAGS ACRS MN AND WI SUNDAY
NIGHT...AND EXTENT OF SFC TO H85 THTA-E ADVECTION AND CONVERGENCE SO
CLOSE TO THE CWA MAKE UNEASINESS FOR DRY FORECAST ACRS THE NORTH.
CHANNELED VORT PUNCH IN TIGHTENING WESTERLIES JUST TO THE NORTH MAY
ALSO HELP LIGHT WEAK SHOWER AND THUNDERSTORMS...WHICH UKMET DRIFTS
DOWN ACRS THE NORTHERN CWA BY 12Z MON. MAY ADD LOW POPS FOR NOW ACRS
THE NORTHERN THIRD FOR THIS POSSIBILITY.

.LONGER TERM(MON-FRI)...WITH PROGRESSIVE ZONAL FLOW PATTERN USHERING
OCCASIONAL WAVES ACRS THE AREA THROUGH AT LEAST MID WEEK...MAY BE
MORE OF A DIFFICULT TASK TO NARROW DOWN DRY DAYS. MONDAY STILL LOOKS
DRY...BUT INDICATIONS THAT NEXT UPSTREAM WAVE WILL CREATE NOCTURNAL
CHANCE THAT NIGHT.  WILL THEN KEEP DAILY CHANCE THROUGH FRIDAY....
POSSIBLY WEEDING OUT WEDNESDAY AS A DRY-LOWER PRECIP CHANCE DAY. MAIN
STORM TRACK SHIFTS ACRS WESTERN CONUS/CANADIAN BORDER BY THU...WITH
UPPER RIDGE FOLDING OVER AREA. THIS MAY MAKE FOR ANOTHER DRY DAY...
BUT MEDIUM RANGE MODEL INDICATIONS DIFFLUENT FLOW ON LEE SIDE MAY
USHER DECAYING MCS DOWN ACRS AREA ON THU OUT OF MN/NORTHERN PLAINS.
LIKE TOUCH COOLER MEX TEMPS UNTIL THU...WHEN THERMAL RIDGE APPROACHES
FROM WEST FOR 80 DEGREE POTENTIAL.

COORDINATED WITH ILX...THANX!


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

12/ERVIN