FXUS63 KLSX 272343
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
543 PM CST FRI NOV 27 2009

.DISCUSSION...
/200 PM CST FRI NOV 27 2009/

MAIN FCST CONCERN WILL BE CHC OF PRECIP FOR SUN INTO SUN NGT ASSOC 
WITH A SYS ALONG THE WRN COAST. 

SFC RIDGE REMAINS IN CONTROL FOR ANOTHER DAY...ALLOWING SLY WINDS TO 
PERSIST UNDER CLEAR SKIES. THESE CONDITIONS WILL PERSIST AGAIN TMW 
AS STRONG WAA HELPS RAISE TEMPS INTO THE 60S ACRS OF THE REGION. 

MDLS AGREE WELL WITH TIMING OF THE APPROACHING CDFNT ON SUN. MDLS 
DEPICT SCHROEDER RULE IN EFFECT ACRS PORTIONS OF SRN MO SUN AND SUN 
NGT. THIS IS ALSO WHERE THE BETTER FORCING WILL BE DURING THIS 
TIMEFRAME. TRIMMED BACK POPS A LITTLE AS THINKING PRECIP WILL BRUSH 
AGAINST OUR SRN CWA BORDER. STILL...GIVEN MDL UNCERTAINTY...WILL 
KEEP POPS AT HIGH END CHC. 

TRENDED TEMPS FOR SAT ABV HIGHEST MOS GUIDE...WITH ONLY MINOR 
CHANGES FROM PREV FCST. THEN...AS THE CDFNT PASSES...TRENDED TEMPS 
TWD THE COOLER MOS OR EVEN BLW FOR SUN INTO MON. 

FOR THE EXTD...MADE ONLY MINOR CHANGES TO THE PREV FCST FOR THIS 
TIME PERIOD. SOME VARIATION IN MDLS...ESP WITH REGARD TO UPR LVL 
TROF CURRENTLY JUST OFF THE WRN COAST. ECMWF/GFS/GEM AGREE WITH THIS 
TROF BCMG CUT OFF ACRS SWRN US AND MOVING ACRS TX EARLY WED. MDLS 
ALSO PLACE A DEEP TROF ACRS THE NRN PLAINS BY THURS. 

HOWEVER...MDLS DISAGREE IN SOLNS WITH THE SRN CUT OFF LOW...AND THE 
MDLS HAVE NOT BEEN CONSISTENT FROM ONE RUN TO THE NEXT. HAVE 
THEREFORE LOW CONFIDENCE IN ANY ONE SOLN FOR WED AND BEYOND. THAT 
SAID...ECMWF/GEM/GEFS ARE IN FAIRLY GOOD AGREEMENT FOR THURS AND 
BEYOND. WILL KEEP THE PREV SILENT 20 POPS GOING DURING THIS TIME AND 
WAIT FOR FUTURE MDL RUNS TO PIN DOWN TIMING. THIS TROF SHUD BE 
COMING ONSHORE AROUND 00Z THIS EVE...GIVING TNGTS MDL RUNS A BETTER 
HANDLE WITH MORE UPR AIR DATA. 

AS FOR TEMPS...TRENDED TWD THE COOLER GUIDANCE THRU WED AS ENSEMBLE 
DATA SUGGESTS GOING COOLER THAN THE EXPLICIT MDLS. TRENDED TWD 
PERSISTENCE FOR THURS AND BEYOND GOING A COUPLE OF DEGREES COOLER 
FOR EACH DAY.

TILLY

&&

.AVIATION...
/540 PM CST FRI NOV 27 2009/

FOR THE 00Z TAFS...HIGH PRESSURE OVER THE OHIO VALLEY WILL MOVE
EAST. WARM FRONT DRAPED ACROSS NORTH CENTRAL MO THEN SE ALONG THE
MISSISSIPPI RIVER WILL DRIFT NORTH. WINDS WILL TRANSITION FROM
LIGHT SOUTHEAST TO LIGHT SOUTH OVERNIGHT THEN TURM MORE SOUTHWEST
SATURDAY MORNING. VFR CEILINGS WITH ONLY CIRRUS APPEARING IN THE
LATTER PART OF THE FORECAST PERIOD. 

JPK

&&

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

$$

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