[LeArc] Forecast Discussion : MLI@ 6/15/2003 4:22:10 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 150915
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
405 AM CDT SUN JUN 15 2003

AS SFC RIDGE SETTLES FURTHER SOUTHEAST OVER THE GRT LKS...WEAK
MOISTURE CONVERGENT ZONE AND BIT HIGHER SFC DPT POOL...THAT HAS BEEN
THE SPAWNING GROUND FOR THE PAST FEW DAYS OF SPOTTY AFTERNOON
CONVECTION IN THE LOCAL AREA...WILL GET SHIFTED TO THE WEST OF THE
CWA. ZONE WILL LOOK TO LIE MAINLY FROM NORTHEAST IA AND THEN
EXTENDING SOUTH-WESTWARD. THUS BETTER CAPES AND INSTABILITIES DEVELOP
IN THESE AREAS THIS AFTERNOON FOR BETTER CHANCE OF SPOTTY POP-UP
THUNDERSTORMS AND SHOWERS TO THE WEST OF AREA OF CONCERN...MAINLY
ACRS CENTRAL AND SOUTHWEST IA. BETTER DEEP CONVECTION INDICES SHIFT
OUT OF THE DVN CWA AND ACRS THESE AREAS TO THE WEST AS WELL. BUT FEEL
ACTIVITY POTENTIAL CLOSE ENOUGH TO INCLUDE SLIGHT CHANCE ACRS THE
WEST AND NORTHWEST THIS AFTERNOON. FCST SOUNDINGS SUGGEST ANOTHER DAY
OF UNSTABLE LOW TO MID LEVELS DEVELOPING BY AFTERNOON IN MUCH OF THE
CWA(ESPECIALLY WESTERN HALF)...AND WARM WEDGE/INVERSION AT AROUND H6
MB AGAIN KEEPING MORE OF A WIDESPREAD POTENTIAL IN CHECK. WITH
CONTINUING INFLUX OF SOMEWHAT DRIER AIR ON DEEPENING LLVL
NORTHEASTERLY FLOW...EASTERN HALF OF THE CWA MAY BE SPARED OF
NUISANCE CONVECTION. BUT...VORT SEEN ON W/V IMAGERY OVER NORTHWEST
MN...IS SIMILARLY PROGGED BY SHORT RANGE MODELS TO DROP DOWN ACRS THE
MN/IA/WI TRI-STATE REGION THROUGH MIDNIGHT. INCOMING CVA MAY SPAWN
WIDELY SCATTERED CONVECTION IN A HIT-AND MISS FASHION ACRS THE
NORTHERN THIRD(INCLUDING NORTHWEST IL) LATE THIS AFTERNOON AND
EVENING...BEFORE FADING AGAIN AFTER SUNSET. WITH SUNSHINE AND BIT
DRIER AIRMASS TO WARM...FEEL WIDESPREAD MID 80S ON TAP AGAIN FOR THE
AREA. SOME SPOTTY 87'S OR 88'S POSSIBLE ACRS THE WEST.

AS VORT SETTLES OVER THE CWA ON MONDAY...DEVELOPING INSTABILITY MAY
KICK UP MORE THUNDERSTORMS ACRS THE SOUTH ON LEADING EDGE OF VORT
GRADIENT. THERMAL PROFILES WITH SLIGHT MODIFICATION FROM THE
NORTHEAST...SUGGEST MONDAY HIGH TEMPS TO BE NEAR OR SLIGHTLY LOWER
THAN PROJECTED FOR TODAY.  ..12..

EXTENDED (WED-SAT)...
POTENTIAL FOR MCS TO IMPACT PORTIONS OF AREA LATE TUE NGT-WED. ECWMF
IS OUTLIER WITH FASTER FRONTAL MOVEMENT AND BRINGS FRONT THROUGH
DURING DAYTIME ON WED. 00Z RUNS OF UKMET...GFS AND MRF ALL HINTING
AT SLOWER MOVEMENT WITH FRONTAL PASSAGE WED NGT-EARLY THU.
FLOW ALOFT FAIRLY LIGHT...BUT IF GOOD COLD POOL CAN DEVELOP ALLOWING
CONVECTION TO ACCELERATE THEN POTENTIAL FOR OUTFLOW TO SWEEP
THROUGH DAYTIME ON WED WITH IMPACTS BOTH TO POPS AND TEMPS.
CHC POPS LOOK GOOD ATTM...THOUGH WILL NEED TO MONITOR NEXT SEVERAL
SHIFTS FOR POTENTIAL UPGRADE INTO LIKELY CAT EITHER TUE NGT
OR WED. AS FOR MAXES WED...UNCERTAINTIES WITH CONVECTION DEBRIS AND
BOUNDARIES WILL PRECLUDE ANY SIGNIFICANT CHANGES. HOWEVER...
THICKNESS WITH FULL SUN WOULD SUPPORT 85-90 DEGS. 00Z UKMET...GFS...
MRF AND ECMWF IN DECENT AGREEMENT ON THU DEPICTING MAIN FRONTAL ZONE
POSITIONED FROM LOWER MISSISSIPPI VALLEY INTO SOUTHEASTERN STATES.
GFS AND MRF THOUGH HINT AT SECONDARY LAKE ENHANCED FRONT AND GENERATE
QPF ESPECIALLY ACROSS THE SOUTH AND WEST. CURRENT FORECAST HAS POPS
MENTIONED FOR THU AND SEE NO REASON TO REMOVE ATTM...AND WILL LET
LATER MODEL RUNS CLARIFY MESOSCALE FEATURES.   ..MWM..

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

$$

12/MWM