[LeArc] Forecast Discussion : MLI@ 6/16/2003 4:42:20 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 160934
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
415 AM CDT MON JUN 16 2003

WELL DEFINED VORT SEEN ON W/V IMAGERY DROPPING DOWN OVER WI ATTM...
WILL LOOK TO CONTINUE TO SPIRAL DOWN ACRS NORTHERN IL THROUGH THIS
AFTERNOON. THUS MAIN FCST QUESTION IN NEAR TERM IS IF FEATURE WILL
BE ABLE TO KICK UP ISOLATED SHOWERS AND THUNDERSTORMS OVER THE LOCAL
AREA. EASTERLY FLOW IN THE LOWER LEVELS OFF GRT LKS RIDGE WILL
CONTINUE TO DRY ADVECT INTO THE CWA TODAY...WITH MSAS LOOP
ALREADY INDICATING LOW TO MID 60 SFC DPT POOL HAS BEEN SHUNTED TO
WESTERN IA. BEST CAPES AND DEEP CONVECTION INDICES WITH DAYTIME
HEATING ALSO TO DEVELOP WELL TO THE WEST OVER WESTERN IA TODAY...
AND THUS FEEL INCOMING CVA WITH UPPER WAVE PROBABLY WON'T PRODUCE
PRECIP CHANCE WORTH MENTIONING IN THE ZONES. STILL WOULDN'T BE
SURPRISED IF AN ISOLATED POP-UP STORM OCCURS SOMEWHERE OVER THE SOUTH
HALF OF THE CWA THIS AFTERNOON...BUT AGAIN RISK RIGHT NOW APPEARS
TOO LITTLE TO MENTION.

WITH ABUNDANT INSOLATION AND APPROPRIATE MIXING IN STEEP LOW TO MID
LEVEL LAPSE RATES...INDICATED ONCE AGAIN ON FCST SOUNDINGS...SEE NO
REASON NOT TO GO WITH PERSISTENCE AND WIDESPREAD MID 80S FOR HIGHS
THIS AFTERNOON.

WITH RIDGE CONTINUING TO INFLUENCE THE AREA ON TUESDAY AND NOT MUCH
CHANGE IN THERMAL PARAMETERS...ANOTHER MOSTLY SUNNY MID 80 DAY
SEEMS TO BE ON TAP.

LOOKING TO UPPER FEATURES...RIDGE IS SIMILARLY PROGGED BY SHORT
RANGE MODELS TO SHARPEN OVER THE CANADIAN ROCKIES TUE NIGHT.
NORTHWEST TERRITORIES VORT COMPLEX WILL THEN LOOK TO SHEAR DOWN IN
AMPLIFYING NORTHWEST FLOW OVER CENTRAL CANADA AND HEAD FOR THE
NORTHERN GRT LKS ON WED. MODELS SUGGEST SOME LEAD VORT PIECES TO
SWIPE DOWN ACRS THE NORTHERN CWA LATER TUE NIGHT...AND 65 KT H25 SUB
JETLET STREAKING OVER WI TO INDUCE SOME RIGHT REAR DIVERGENT
INFLUENCE OVER NORTHEAST IA. ETA/ META SUGGEST EVEN SOME POS OMEGAS
DEVELOPING OVER THE NORTHERN CWA AS TUES NIGHT PROGRESSES. WITH THESE
FACTORS...WILL INTRODUCE LATE NIGHT POPS ACRS THE NORTHWEST CWA WITH
POTENTIAL OF UPSTREAM ACTIVITY FROM APPROACHING FRONTAL SYSTEM TO
BLEED INTO THE CWA.  ..12..

ON WED ECMWF REMAINS OUTLIER WITH QUICKER FRONTAL PASSAGE. EXPECT
NORTHERN END OF FRONT TO BE MORE PROGRESSIVE BEING CLOSER TO MAIN
WESTERLIES. CAPPING INVERSION AND WEAK SURFACE CONVERGENCE SHOULD
LIMIT PCPN TO MAINLY POST FRONTAL. POTENTIAL FOR SEVERE WX APPEARS
LIMITED DUE TO LACK OF COHERENT MID LEVEL TRIGGER...EVEN THOUGH MID
LEVEL FLOW AND SHEAR WILL BE INCREASING A BIT. TEMPS WILL BE SOMEWHAT
CHALLENGING AND DEPENDENT ON 1) EXTENT OF CONVECTIVE DEBRIS AND 2)
TIMING OF FRONTAL PASSAGE. SLOWER FRONTAL PASSAGE AND/OR MORE
SUNSHINE WOULD SPELL WARMER READINGS WITH POTENTIAL TO BE NEAR 90
DEGS IN SOME LOCATIONS BASED ON LLVL THICKNESS.

EXTENDED (THU-SUN)...HIGH PRESSURE SETS UP OVER GREAT LAKES EARLY ON
AND THEN DRIFTS INTO OHIO VALLEY BY WEEKEND. THIS SHOULD SET THE
STAGE FOR VERY COMFORTABLE CONDITIONS LATE WEEK AND TO START THE
WEEKEND WITH LOW HUMIDITIES AND TEMPS NEAR TO BELOW NORMAL.
REMOVED PCPN FROM FORECAST ON THU WITH SURFACE RIDGE OVERHEAD
SUPPRESSING MAIN SYNOPTIC BOUNDARY INTO LOWER MISSISSIPPI VALLEY AND
SOUTHEASTERN STATES. IN THIS PATTERN...GUIDANCE TYPICALLY TOO WARM
ON MINS THUS HAVE LOWERED FROM PREVIOUS FORECAST. 00Z/16 MEX
GUIDANCE PLAYING CATCH UP AND IS 5 DEGS COOLER ON MINS BOTH THU AND
FRI MORNINGS. OF CONCERN...AND SOMETHING FOR LATER SHIFTS TO
MONITOR...WILL BE POTENTIAL FOR LOW CLOUDS AND COOLER MAXES. SIMILAR
SITUATION TO JUST UNDER A WEEK AGO...WHERE LAKE ENHANCED
NORTHEAST FETCH GENERATED LOW CLOUDS AND KEPT TEMPS WELL BELOW
NORMAL FOR A FEW DAYS. SURFACE HIGH PROGGED FOR THE LATE WEEK IS EVEN
STRONGER THAN LAST WEEK/S...SO POTENTIAL WOULD APPEAR TO BE
QUITE HIGH...NO PUN INTENDED. NEXT CHC OF PCPN LOOKS TO BE LATE IN
THE WEEKEND AND EARLY NEXT WEEK AHEAD OF APPROACHING FRONT AND MID
LEVEL WAVE. COULD BE A DECENT PCPN EVENT GIVEN THE AMOUNT OF FORCING
AND MOISTURE RETURN.  ..MWM..


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

$$

12/MWM