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000
FXUS63 KLSX 131709
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1209 PM CDT MON MAY 13 2013

.UPDATE...
ISSUED AT 1043 AM CDT MON MAY 13 2013

UPDATED TO REDUCE CLOUD COVER INTO THE AFTERNOON AND TO ADJUST
WIND...MAINLY FOR DIRECTION AND THE SFC RIDGE CONTINUES TO PULL
EWD OUT OF THE AREA.

&&

.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 352 AM CDT MON MAY 13 2013

WILL LEAVE CURRENT FROST ADVISORY AS IS OVER THE SOUTHERN THIRD OF
THE CWA THROUGH 7 AM.  TEMPERATURES HAVE ALREADY FALLEN INTO THE
MID-UPPER 30S OVER THE EASTERN OZARKS INCLUDING 33 AT A MESONET
STATION IN SOUTHERN CRAWFORD COUNTY.  DEWPOINT DEPRESSIONS ARE 1-2
DEGREES WITH EXCELLENT RADIATIONAL COOLING...SO FROST SHOULD BECOME
MORE COMMON WITH TIME OVER THE EASTERN OZARKS WITH PATCHY FROST
ELSEWHERE.

WINDS WILL TURN OUT OF THE SOUTH TODAY AS SURFACE RIDGE MOVES EAST
OF THE CWA.  AGREEABLE MOS HIGHS ARE SUPPORTED BY MIXING DOWN THE
8-12C 850MB TEMPERATURES THAT WILL ADVECT IN FROM THE WEST THIS
AFTERNOON.

BRITT

.LONG TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 352 AM CDT MON MAY 13 2013

A DRAMATIC WARMING TREND WILL BEGIN MON NGT AS AN UPPER LEVEL RIDGE
SHIFTS EWD INTO MO...AND W-SWLY LOW LEVEL WINDS BRING STRONG LOW-
MID LEVEL WAA TO THE FORECAST AREA WITH 20 DEGREE C 850 MB
TEMPERATURES ADVECTING EWD TO STL TUE MRNG. MID-HIGH LEVEL CLOUDS
WILL ADVECT E OF OUR AREA BY LATE MON NGT ALLOWING PLENTY OF
SUNSHINE FOR TUE. TUESDAY SHOULD BE THE WARMEST DAY WITH HIGHS
ABOUT 15 DEGREES ABOVE NORMAL. LOOKS LIKE ANY CONVECTION WILL HOLD
OFF TIL WED AFTN AS SHORTWAVES OVER THE NRN PLAINS AND GREAT LAKES
REGION FLATTEN THE UPPER LEVEL RIDGE AND A SRN STREAM UPPER LEVEL
TROUGH MOVES SLOWLY EWD THROUGH THE SRN PLAINS. AN E-W COLD FRONT
WILL SAG SWD INTO NRN MO WED AFTN PER THE ECMWF AND GFS MODELS...
THE NAM IS A LITTLE FURTHER S WITH THIS FRONT. AS LOW LEVEL
MOISTURE AND INSTABILITY INCREASES CONVECTION SHOULD DEVELOP
ALONG THIS BOUNDARY WED AFTN. THIS FRONT MAY SAG AS FAR SWD AS
CNTRL MO WED NGT...THEN BECOME MORE NW TO SE ORIENTED ON THU AS A
SFC RIDGE SHIFTS EWD INTO THE GREAT LAKES REGION. CONVECTION WILL
CONTINUE ALONG THIS BOUNDARY WED NGT THROUGH THU NGT...THEN
LIKELY SHIFT N OF OUR FORECAST AREA AS THE FRONT LIFTS N-NE OF OUR
REGION AS THE UPPER LEVEL RIDGE BUILDS OVER THE CNTRL US AGAIN.
HIGH TEMPERATURES WILL LOWER SOME...CLOSER TO NORMAL VALUES BY
THU...BUT THEN SHOULD WARMUP TO ABOVE NORMAL VALUES FOR FRI AND
SAT DUE TO THE PERSISTENT S-SWLY SFC/LOW LEVEL FLOW AND UPPER
LEVEL RIDGING OVER THE AREA. THE GFS MODEL BRINGS AN UPPER LEVEL
TROUGH EWD THROUGH THE NRN PLAINS ON SAT NGT AND SUN WHICH WILL
BRING A COLD FRONT SEWD THROUGH OUR AREA SUN AND SUN EVNG.
CONVECTION IS EXPECTED ALONG AND JUST AHEAD OF THIS FRONT. THE
ECMWF MODEL IS A LITTLE SLOWER WITH THIS UPPER LEVEL TROUGH AND
ASSOCIATED COLD FRONT WITH MOST OF THE CONVECTION IN OUR AREA SUN
AFTN AND NGT.

GKS

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1206 PM CDT MON MAY 13 2013

VFR AND DRY THRU THE PERIOD. SLY WINDS BECOME SWLY TUES MORNING
AND INCREASE TO AROUND 12 KTS.

SPECIFICS FOR KSTL...VFR AND DRY THRU THE PERIOD. SWLY WINDS SHUD
BECOME SSELY EARLY THIS AFTERNOON. WINDS WILL BECOME SWLY TUES
MORNING AND INCREASE TO 12 KTS WITH GUSTS IN THE 20 KT RANGE LATE
IN THE MORNING AND INTO THE AFTERNOON.

TILLY

&&

.CLIMATE...
ISSUED AT 1047 AM CDT MON MAY 13 2013

RECORD HIGHS

              5/14

ST LOUIS    91 (1931)

COLUMBIA    90 (1987)

QUINCY      94 (1915)


&&

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

$$

WFO LSX