[LeArc] Forecast Discussion : MLI@ 3/20/03 3:14:46 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 200922
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
315 AM CST THU MAR 20 2003

UPPER LOW CHURNING OVER EASTERN KS AND WESTERN MO PER PROFILERS AND 
REGIONAL RADAR TAKING ON MORE N-S ORIENTATION. MODELS SIMILAR IN 
OPENING IT INTO WAVE AND LIFTING IT E/NE INTO MISS VALLEY NEXT 24 HRS
WHICH IS SUPPORTED BY MID/UPPER LEVEL PRESSURE FALLS CENTERED
FROM EASTERN IA SOUTH THROUGH CENTRAL IL PER 00Z ANALYSIS. SHORTWAVE 
OVER SASKATCHEWAN DIVING SOUTH INTO NORTHERN PLAINS WILL DEEPEN 
AS IT DIGS INTO LONGWAVE TROUGH OVER MIDWEST BY FRI. WELL DEFINED WARM
FRONT ARCING FROM SURFACE WAVE NEAR JOPLIN MO NORTHEAST TO 
NEAR A LINE FROM KIRKSVILLE TO QUAD CITIES...TO FREEPORT. WIDESPREAD DENSE 
FOG TO WEST/NORTHWEST OF THIS BOUNDARY IS REDUCING VISIBILITIES TO
NEAR ZERO AT TIMES. FRONTAL ZONE MAY MOVE BIT FURTHER WEST...BUT OVERALL
LITTLE CHANGE WITH WEAK FLOW...WET GROUND AIDING FOG. 
THUS...WILL GO AHEAD AN ISSUE DENSE FOG ADVISORY FOR LOCATIONS MAINLY 
WEST OF A LINE FROM FREEPORT...TO WASHINGTON AND MEMPHIS MO.
FOG SHOULD BEGIN TO LIFT MID-LATE MORNING (OR SOONER ON EASTERN FRINGES
OF ADVISORY) AS WINDS INCREASE. RADAR FAIRLY QUIET ATTIM WITH
FEW SHOWERS MAINLY EAST OF MISSISSIPPI RIVER. WILL EVALUATE PCPN CHCS
BEFORE ZONE ISSUANCE. EARLIER THINKING WAS TO MAINTAIN 
LIKELY POPS FOR MAINLY THIS AFTERNOON AS SEVERAL WEAK SHORTWAVES ROTATE
NORTHWARD AHEAD OF UPPER LOW. LAPSE RATES FAIRLY STEEP ALONG AND
EAST OF MISSISSIPPI RIVER THIS AFTERNOON. LOW LEVEL MOISTURE LIMITED
BUT POTENTIAL EXISTS FOR FEW STORMS TO DEVELOP ALONG AND
EAST OF FRONTAL ZONE...WITH INCREASING INSTABILITY AND STEEPENING LAPSE
RATES. COULD SEE SOME HAIL GIVEN PROXIMITY TO COLD POOL AND EVEN
GUSTY WINDS WITH INVERTED V TYPE SOUNDINGS. OVERALL...ORGANIZED SEVERE
CONVECTION UNLIKELY WITH LACK OF SIGNIFICANT TRIGGER AND DEEP MOISTURE.
TEMPS AGAIN CHALLENGING TODAY. ETA TEMPS LOOK A BIT WARM GIVEN
WET GROUND AND STRONG SHALLOW INVERSION...SO WILL LEAN TOWARD MIDDLE
OF ROAD FWC GUIDANCE. POTENTIAL FOR SIGNIFICANT BUST ON TEMPS IF FEW HOURS
OF SUNSHINE ARE REALIZED.  

WILL MAINTAIN PCPN MENTION TONIGHT WITH HIGHEST POPS EAST AHEAD OF FRONTAL
ZONE. NORTHERN STREAM SHORTWAVE TO DIVE THROUGH MIDWEST LATE
TONIGHT AND FRI. MAIN SHOT OF PVA 06Z-15Z...AND FOCUSED MAINLY ACROSS THE
NORTH. STEEP LAPSE RATES...UPPER DIFFLUENCE AND COLD POCKET WILL
RESULT IN SLGT CHC POPS FOR FRI AFTN WITH POTENTIAL FOR MODERATE TO 
STRONG CONVECTIVE SHOWERS WITH SOUNDINGS DEPICTING SMALL POSITIVE AREA OF CAPE
AND WBZ >2500' AGL...THUS CAN/T RULE OUT SOME SLEET MAINLY NORTH
WITH ANY SHOWERS THAT MAY FORM. SYSTEM EXITS FRI NIGHT WITH CYCLONIC LLVL
FLOW AND COLD POCKET POSSIBLY PRODUCING FEW FLURRIES NORTH.

MODELS INDICATE ZONAL FLOW DEVELOPING OVER WEEKEND...WITH MODERATING
TEMPS. BY EARLY NEXT WEEK TEMPS TO BE 10-15 DEGS ABOVE NORMAL.

DMX...THANX FOR COORDINATION. 

.DVN...
IA...DENSE FOG ADVISORY TIL 10 AM ROUGHLY ALONG AND WEST OF A DUBUQUE TO
WASHINGTON. 
IL...DENSE FOG ADVISORY TIL 10 AM JO DAVIESS COUNTY.
MO...DENSE FOG ADVISORY TIL 10 AM SCOTLAND COUNTY.

$$

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