National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KLSX 141737
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1237 PM CDT TUE MAY 14 2013

.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 300 AM CDT TUE MAY 14 2013

NORTH-SOUTH ORIENTED WARM FRONT THAT IS OVER EASTERN MISSOURI EARLY
THIS MORNING WILL MOVE NORTHEASTWARD SETTING UP FOR A VERY WARM DAY
TODAY. STILL EXPECT DRY WEATHER AS HEIGHTS BUILD AND WARM LAYER
BETWEEN 900-800MB CAPS WHAT INSTABILITY DEVELOPS DURING THE DAY.
STILL EXPECT TEMPERATURES TO CLIMB INTO 85-90 DEGREE RANGE THIS
AFTERNOON GIVEN AMPLE SUNSHINE...STRONG WARM AIR ADVECTION AND
FAVORABLE SOUTHWEST WIND DIRECTION. MODEL FORECAST SOUNDINGS
SUGGESTS THAT WE ONLY MIX UP TO BETWEEN 925-900MB...THOUGH IF WE
WERE TO MIX UP TO 850MB...HIGHS WOULD BE WELL INTO THE 90S ACROSS
CENTRAL AND NORTHEAST MISSOURI BASED ON 20-22C TEMPERATURES AT
THIS LEVEL. FORECAST DEWPOINTS FOR TODAY SEEM TO BE TOO HIGH
BASED ON UPSTREAM READINGS...SO TRIMMED THEM BACK BY A FEW
DEGREES.

BRITT

.LONG TERM...(TONIGHT THROUGH MONDAY)
ISSUED AT 329 AM CDT TUE MAY 14 2013

SWLY SFC/LOW LEVEL WINDS TGT WILL CONTINUE THE WARMING TREND.  THE
THREAT OF CONVECTION WILL BEGIN WED AFTN AS SHORTWAVES MOVING E-SEWD
THROUGH THE NRN PLAINS AND GREAT LAKES REGION FLATTEN THE UPPER
LEVEL RIDGE AND A SLOW MOVING UPPER LEVEL LOW/TROUGH MOVING EWD
THROUGH THE SRN PLAINS BRINGS INCREASING MOISTURE NWD INTO MO.  THE
BEST THREAT FOR CONVECTION ON WED AFTN WILL LIKELY BE ACROSS NERN MO
AND W CNTRL IL ALONG A COLD FRONT WHICH WILL SAG SWD INTO NRN MO AND
CNTRL IL. IT WILL BE QUITE UNSTABLE ALONG AND S OF THIS E-W BOUNDARY
ALTHOUGH THE MODELS MAY BE A LITTLE TOO HIGH ON AFTN SFC DEW
POINTS. HIGH TEMPERATURES ON WED WILL NOT BE AS WARM AS TUE BUT
STILL ABOVE NORMAL. CONVECTION WILL CONTINUE WED NGT PARTICULARLY
N OF I-70 ALONG THE E-W FRONT...WITH MORE SCATTERED ACTIVITY
FURTHER S AHEAD OF THE UPPER LEVEL LOW/TROUGH. HIGHS ON THU WILL
BE CLOSER TO SEASONAL NORMALS DUE TO CLOUD COVER AND AS THE UPPER
LEVEL TROUGH MOVES SLOWLY EWD THROUGH SRN MO AND AR AND EVENTUALLY
INTO THE TN VALLEY REGION. CONVERGENCE ALONG THE FRONT WILL BEGIN
TO WEAKEN AND THE WRN PORTION OF THE FRONT WILL BEGIN TO LIFT NWD
AS A SFC RIDGE MOVES EWD FROM THE NRN PLAINS INTO THE GREAT LAKES
REGION. IT APPEARS THAT THE HIGHEST PROBABILITY FOR CONVECTION
WILL BE ACROSS NERN MO AND IL ON THU. THE CHANCE OF RAIN WILL
DIMINISH THU NGT AS THE FRONT LIFTS N-NE OF OUR FORECAST AREA...AND
THE SRN STREAM UPPER LEVEL TROUGH/LOW SHIFTS SE OF THE REGION.
THE ECMWF AND GFS MODELS WERE FORECASTING A VORT MAX TO MOVE EWD
THROUGH NRN MO ON FRI AND CNTRL IL FRI NGT. THE GFS MODEL APPEARS
TO HAVE SOME FEEDBACK PROBLEMS AND IS TOO STRONG AND SLOW MOVING
WITH THIS FEATURE AND IS OVERDONE WITH ITS QPF BUT THERE COULD
STILL BE SOME CONVECTION AHEAD OF THIS VORT MAX. THE UPPER LEVEL
RIDGE WILL BUILD OVER THE CNTRL US AGAIN INTO THE WEEKEND...AND
THIS ALONG WITH THE PERSISTENT SLY SFC/LOW LEVEL FLOW WILL CAUSE
HIGH TEMPERATURES TO WARM UP WELL INTO THE 80S FOR SAT. MORE
WIDESPREAD AND ORGANIZED CONVECTION IS LIKELY BEGINNING SUN AFTN
AND CONTINUING THROUGH MON AS AN UPPER LEVEL TROUGH AND ASSOCIATED
COLD FRONT APPROACH OUR FORECAST AREA. THE MODELS WERE A LITTLE
SLOWER WITH THIS STORM SYSTEM...NOT MOVING THE COLD FRONT SEWD
THROUGH OUR FORECAST AREA UNTIL MON NGT.

GKS

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1222 PM CDT TUE MAY 14 2013

GUSTY SOUTHWEST WINDS THIS AFTERNOON WILL TAPER OFF AFTER SUNSET
THIS EVENING...THOUGH DO NOT EXPECT MUCH CHANGE IN THE SUSTAINED
WIND SPEEDS ACROSS THE TAF SITES. CLEAR SKIES TONIGHT WILL GIVE
WAY TO INCREASING UPPER AND MID LEVEL VFR CLOUDS BEGINNING ON
WEDNESDAY MORNING AHEAD OF AN APPROACHING SYSTEM. WINDS WILL REMAIN
SOUTHWESTERLY THROUGH THE FORECAST PERIOD...THOUGH KUIN WILL SEE
WINDS VEER TO A MORE WESTERLY DIRECTION AS A FRONTAL BOUNDARY
DRIFTS SOUTHWARD INTO NORTHERN MISSOURI WEDNESDAY MORNING/EARLY
AFTERNOON.

SPECIFICS FOR KSTL...
GUSTY SOUTHWEST WINDS WILL CONTINUE THIS AFTERNOON BEFORE
DIMINISHING AFTER SUNSET THIS EVENING. DO NOT EXPECT MUCH CHANGE
IN SUSTAINED WIND SPEED TO OCCUR DUE TO PERSISTENT RETURN FLOW
ENTRENCHED OVER THE REGION. VFR CONDITIONS WILL PREVAIL THROUGH
THE TAF PERIOD...THOUGH DO EXPECT INCREASING UPPER AND MID LEVEL
CLOUDS BY WEDNESDAY MORNING. THE MAIN QUESTION REVOLVES AROUND
POTENTIAL SHRA/TSRA ON WEDNESDAY AFTERNOON/EVENING AS A FRONTAL
BOUNDARY MOVES INTO NORTHERN MISSOURI...THOUGH TO CURRENT MODEL
VARIANCES...HAVE KEPT KSTL DRY FOR NOW AND WILL DEFER PRECIP
MENTION TO LATER TAF ISSUANCES.

JP

&&

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

RECORD HIGHS FOR TUESDAY (5/14)

ST LOUIS    91 (1932)

COLUMBIA    90 (1987) (1932)

QUINCY      94 (1915)


&&

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

$$

WFO LSX