248
FXUS63 KLSX 272002
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
202 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
/1128 AM CST FRI NOV 27 2009/
FOR THE 18Z TAFS...
DRY AND VFR CONDITIONS WITH NO MORE THAN FEW-SCT250 CIRRUS OVER
THE NEXT 24-30 HOURS. EASTERN EDGE OF WARM FRONT EXTENDING FROM
NRN MO NWWD INTO THE DAKOTAS IS CAUSING THE DIFFERENCE BETWEEN
SWLY SFC WNDS OVER CNTRL MO AND SELY WINDS OVER IL. THINK THIS
FRONT WILL MOVE NEWD AND WINDS AT TAF SITES WILL BECOME DOMINATELY
S-SWLY THIS AFTERNOON WITH LIGHT WINDS TONIGHT.
BRITT
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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