000 
FXUS63 KLSX 191134
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
634 AM CDT THU MAR 19 2009

.DISCUSSION...
/439 AM CDT THU MAR 19 2009/
BAND OF POST FRONTAL SHOWERS WILL DROP S OF THE CWA BY 12Z THU AS
SFC RDG OVER THE NRN PLAINS BLDS SWD THRU THE CWA...AND AS DRIER
LOW LVL AIR ADVCTS SWD THRU THE AREA BHND THE 850 MB FNT/TROF. THE
LOW LVL CLOUD CVR WILL ALSO CLR OUT OF THE SRN PTN OF THE CWA THIS
MRNG...WITH JUST SOME MID-HI LVL CLOUDS MOVG SEWD ACRS THE CWA
THIS AFTN. WILL FCST MAX TEMPS TDA BLW PERSISTENCE WITH LOW LVL
CAA AS THE MDLS ADVCT THE ZERO DGR C 850 MB ISOTHERM SWD TO JUST
S OF STL BY 00Z FRI. ALTHOUGH IT WILL BE COOLER TDA TEMPS SHOULD
STILL BE NR SEASONAL NORMALS. TEMPERATURES TGT MAY BE SLIGHTLY BLW
SEASONAL NORMALS THOUGH WITH GOOD RADIATIONAL COOLING UNDERNEATH SFC
RDG AXIS ACRS THE CWA DUE TO A MOSTLY CLR SKY...DIMINISHING SFC
WNDS...AND SFC DWPTS ONLY IN THE 20S TO NR 30. SHOWERS SHOULD
RETURN TO AREAS MAINLY W OF THE MISSISSIPPI RVR LT FRI NGT AS A
SWLY LLJ BRINGS LOW LVL WAA AND INCRSG LOW LVL MOISTURE BACK INTO
THE AREA. THE NAM MDL INCRS THE K INDICES TO NR 30 IN CNTRL MO BY
12Z SAT. THESE ELEVATED SHOWERS AND MAYBE ISOLATED THUNDERSTORMS WILL
DROP SEWD THRU MAINLY THE SRN OR SWRN PTN OF THE CWA SAT MRNG. THE
FOCUS FOR CONVECTION SHOULD SHIFT TO THE NRN PTN OF THE CWA SAT
NGT AND SUN AS A WK WRMFNT LIFTS NWD THRU THE REGION. FOLLOWED THE
ECMWF AND GFS FCST SOLUTION OVER THE NAM MDL FOR SAT NGT AND SUN.
THE NAM SHIFTS THE PCPN N OF THE CWA BY THIS TIME PD WHILE THE
ECMWF AND GFS STILL GENERATE QPF MAINLY OVER THE NRN PTN OF THE
CWA. THE GFS MDL MAY BE TOO GENEROUS WITH QPF THOUGH OVER NRN MO
SAT NGT AS IT APRS TO HAVE SOME FEEDBACK PROBLEMS. WARMER
TEMPERATURES ARE EXPECTED ON SUN WITH INCRSG SLY LOW LVL FLOW...AND
WITH A MID-UPR LVL RDG MOVG EWD THRU THE CWA.

GKS

&&

.AVIATION...
/615 AM CDT THU MAR 19 2009/
FOR THE 12Z TAFS...
VFR CONDITIONS EXPECTED THROUGH THE ENTIRE PERIOD AS HIGH PRESSURE
BUILD INTO THE AREA. PRECIP HAS CLEARED ALL BUT EXTREME SE MO.
CLEARING LINE IS WELL SOUTH OF KCOU AND THE STL METRO SITES. EXPECT
AN AREA OF MID CLOUDS 10-12 KFT TO MOVE ACROSS MO AND SOUTHERN IL
DURING THE MID- DAY. WINDS WILL REMAIN OUT OF THE NORTH
TODAY...THEN GRADUALLY SWING AROUND TO THE EAST OVERNIGHT AS
SURFACE HIGH PASSES OFF TO THE NE.

MILLER

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&

$$

WFO LSX