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000
FXUS63 KLSX 241753
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
1253 PM CDT FRI MAY 24 2013

.UPDATE...
ISSUED AT 1252 PM CDT FRI MAY 24 2013

GOING FORECAST STILL LOOKING GOOD FOR THIS AFTERNOON.

TRUETT

&&

.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 315 AM CDT FRI MAY 24 2013

THE ELONGATED SURFACE HIGH CURRENTLY STRETCHING THROUGH THE UPPER-
MIDDLE MS VALLEY WILL CONTINUE TO DOMINATE THE SENSIBLE WEATHER AS
IT SLOWLY MOVES EASTWARD. THIS SYSTEM WILL CONTINUE TO BRING BELOW
AVERAGE TEMPERATURES...BUT UNLIKE YESTERDAY...TODAY THERE WILL BE
ABUNDANT SUNSHINE RESULTING IN WARMER TEMPERATURES.

GLASS

.LONG TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 315 AM CDT FRI MAY 24 2013

THE UPPER AIR PATTERN WILL UNDERGO PROGRESSION AND DEAMPLIFICATION
OVER THE WEEKEND INTO MONDAY RESULTING IN AN EXTENDED PERIOD OF
UNSETTLED WEATHER FOR PARTS OF THE CWA. THE PLAINS UPPER RIDGE
WILL PROGRESS EASTWARD INTO THE MS VALLEY TODAY AND THEN FLATTEN
BEGINNING TONIGHT AS A SERIES OF WEAK SHORT WAVES TOP THE RIDGE AND
SPILL NEWD WITHIN THE WEAK WNW FLOW ALOFT ON THE DOWNSTREAM SIDE.
THE BIGGEST PROBLEM IS THE MODELS SHOW A FAIR AMOUNT OF SPREAD IN
THE TIMING/POSITION OF THESE WAVES TONIGHT THROUGH MONDAY. THE LOW
LEVEL WAA REGIME WILL GET UNDERWAY TONIGHT IN THE WAKE OF THE
RETREATING SURFACE HIGH/LOW LEVEL ANTICYCLONE...HOWEVER MOISTURE
RETURN LOOKS TO BE DELAYED A BIT UNTIL SATURDAY. WITH THIS IN
MIND...I HAVE TO BELIEVE THE ECMWF IS A BIT AGGRESSIVE WITH QPF
EARLY ON. HOWEVER BY MIDDAY SATURDAY...AN INTENSIFYING WAA REGIME
AND SWLY LLJ SHOULD ACCELERATE THE MOISTURE TRANSPORT AND ASCENT
ACROSS THE AREA INTERACTING WITH THE MIGRATORY SHORT WAVES...
RESULTING IN MULTIPLE WAVES OF SHOWERS AND THUNDERSTORMS FROM
SATURDAY INTO MONDAY. THE HIGHEST THREAT AREA LOOKS LIKE THE
NORTHERN THIRD TO HALF OF THE CWA. FINALLY ON TUESDAY THE WARM
FRONT LIFTS NORTH OF THE AREA AS THE UPPER RIDGE BUILDS FROM THE
LOWER MS VALLEY INTO THE EASTERN U.S. BRINGING MUCH WARMER
TEMPERATURES AND LESSER PRECIPITATION CHANCES UNTIL LATE NEXT
WEEK.

GLASS

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1252 PM CDT FRI MAY 24 2013

SURFACE RIDGE AXIS EXTENDING FROM E WI TO SE MO WILL CONTINUE TO
SLIDE EAST THIS AFTERNOON AND TONIGHT. THIS WILL MEAN THAT VFR
CONDITIONS WILL PREVAIL THROUGH 06Z...WITH CLOUDS LIMITED TO A BIT
OF CI AND EAST-SE SURFACE WINDS PRIMARILY AOB 10 KTS.  ATTENTION
THEN TURNS TO THREAT OF NOCTURNAL CONVECTION.  THERE SEEMS TO BE
SOME CONSENSUS IN THE LATEST SHORT RANGE THAT THETA-E ADVECTION ON
NOSE OF LOW LEVEL JET WILL BE WELL TO OUR N...CAUSING THE
DEVELOPMENT AND CENTROID OF THE MCS TO TRACK ACROSS IOWA AND THEN
EITHER ADVECT OR ATTEMPT TO DEVELOP A BIT SOUTH INTO N SECTIONS OF
THE CWA DURING THE PREDAWN HOURS. BASED ON THIS TREND HAVE
INTRODUCED VCTS IN UIN BY 12Z..BUT ELSEWHERE HAVE HELD OFF
MENTIONING THUNDER ATTM AS SOLUTIONS ARE LITERALLY ALL OVER THE
PLACE WITH CONVECTIVE TRENDS DURING THE DAY ON SATURDAY. DETAILS
FOR SATURDAY SHOULD BECOME A BIT MORE CLEAR ONCE TONIGHTS
CONVECTIVE TRENDS BECOME ESTABLISHED.

SPECIFICS FOR KSTL...VFR CONDITIONS WILL PREVAIL THROUGH 15Z
SATURDAY...WITH NE WINDS AOB 8 KTS THIS AFTERNOON BECOMING
EASTERLY TONIGHT AND SE ON SATURDAY. SHOULD SEE AN INCREASE IN MID
AND HIGH LEVEL CLOUDS LATE TONIGHT AND SATURDAY MORNING AS CLOUD
DEBRIS STREAMS DOWNSTREAM FROM IOWA/N MO CONVECTION...BUT THESE
SHOULD BE AOA 10KFT.

TRUETT

&&

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

$$

WFO LSX