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000
FXUS63 KLSX 151626
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
1126 AM CDT WED MAY 15 2013

.UPDATE...
ISSUED AT 1112 AM CDT WED MAY 15 2013

COLD FRONT MAKING SLOW PROGRESS INTO FAR NORTHERN REACHES OF
MISSOURI THIS MORING. BOOSTED TEMPERATURES A FEW DEGREES FOR HIGHS
GIVEN RECORD WARM START AND PLENTY OF SUNSHINE SOUTH OF THE FRONT
AND AHEAD OF THE APPROACHING UPPER LEVEL LOW TO OUR SOUTHWEST.
COULD FLIRT WITH RECORD HIGHS AGAIN TODAY AT KCOU AND KSTL.

KCOU RECORD HIGH TEMPERATURE FOR TODAY IS 90F (1944/1941/1911)
KSTL RECORD HIGH TEMPERATURE FOR TODAY IS 94F (1944)

THUNDERSTORM CHANCES TO INCREASE LATE THIS AFTERNOON AND INTO THE
EVENING...WITH TWO POSSIBLE AREAS OF FOCUS. THE FIRST WILL BE FROM
A WAVE OF VORTICITY FROM THE UPPER LOW THAT SPINS OUT AHEAD OF THE
SYSTEM ACROSS THE OZARKS. THIS SHOULD BE DIURNALLY DRIVEN GIVEN
WEAK FORCING...AND HAVE KEPT POPS IN SLIGHT CHANCE CATEGORY. THE
SECOND AND MORE PROMISING FOCUSING FEATURE WILL BE THE COLD FRONT
THAT WILL HAVE BECOME NEARLY STATIONARY ACROSS THE FAR NORTHERN
STRETCHES OF THE CWA. HERE...CONVECTION IS MORE LIKELY TO DEVELOP
AND POPS ARE IN THE CHANCE TO LIKELY CATEGORY INTO THE EVENING HOURS.

CAN`T RULE OUT A FEW WIND GUSTS AND SMALL HAIL REPORTS...BUT
ORGANIZED SEVERE WEATEHR IS NOT EXPECTED GIVEN LACK OF DEEP LAYER
SHEAR.

CVKING

&&

.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 322 AM CDT WED MAY 15 2013

MAIN CONCERN IS THE POTENTIAL FOR A FEW STRONG THUNDERSTORMS THIS
AFTERNOON.  A COLD FRONT CURRENTLY STRETCHES ACROSS EASTERN AND
SOUTHERN IOWA INTO SOUTHERN NEBRASKA.  THIS FRONT WILL BE ABLE TO
MOVE INTO NORTHERN MO/CENTRAL IL THIS AFTERNOON BEFORE IT STALLS
BETWEEN THE STRONG WESTERLIES OVER THE UPPER MIDWEST AND THE UPPER
LOW OVER THE SOUTHERN PLAINS.  THIS FRONT WILL PRODUCE SOME WEAK
CONVERGENCE OVER THE NORTHERN PART OF THE CWA.  AT THE SAME TIME...
THERE WILL BE SOME WEAK ASCENT THAT WILL MOVE INTO THE AREA FROM THE
SOUTHWEST AHEAD OF A VORT LOBE AND ASSOCIATED 925-850MB MOISTURE
CONVERGENCE.

WHILE NONE OF THIS FORCING IS PARTICULARLY IMPRESSIVE...INSTABILITY
WILL BE INCREASING TODAY AS DEWPOINTS INCREASE TO NEAR 60.  THESE
VALUES ARE BELOW THE FORECAST VALUES OF THE MODELS BECAUSE THEY HAVE
HAD A WET BIAS THE PAST FEW DAYS...BUT DO THINK THAT TEMPERATURES
COULD VERY WELL BE A FEW DEGREES WARMER THAN MOS GUIDANCE GIVEN THE
CURRENT READINGS ARE RELATIVELY WARM AND FORECAST SOUNDINGS SHOW
MIXING INTO THE 850-800MB RANGE.  CURRENTLY THINK THAT ANY
THUNDERSTORM DEVELOPMENT WILL BE SCATTERED AS A PROGGED WARM LAYER
BETWEEN 800-700MB WILL LIMIT AREAL EXTENT.  DO NOT EXPECT ORGANIZED
THUNDERSTORMS TODAY...THOUGH WITH MLCAPES AROUND 1500 J/KG AND DEEP
MIXING SUGGEST THAT SOME LOCALLY STRONG WIND GUSTS WILL BE POSSIBLE
WITH A FEW STORMS.

BRITT

.LONG TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 322 AM CDT WED MAY 15 2013

THE HIGHEST PROBABILITY FOR SHOWERS AND STORMS SHOULD OCCUR ACROSS
NERN MO AND W CNTRL IL TGT ALONG AN E-W FRONT. MORE SCATTERED
ACTIVITY IS EXPECTED FURTHER S ACROSS PORTIONS OF SERN MO AHEAD OF
A SLOW MOVING UPPER LEVEL TROUGH/LOW. THIS FRONT SHOULD WEAKEN AND
BECOME MORE NW TO SE ORIENTED THU AS A SFC RIDGE MOVES EWD
THROUGH THE GREAT LAKES REGION WITH THE WRN PORTION OF THE FRONT
LIFTING NWD. THE UPPER LEVEL LOW/TROUGH WILL MOVE EWD THROUGH SRN
MO AND NRN AR. THERE SHOULD BE AT LEAST SCATTERED STORMS OVER MUCH
OF THE FORECAST AREA ON THU. HIGH TEMPERATURES ON THU WILL BE COOLER
...ALBEIT STILL ABOVE SEASONAL NORMALS. MAY GET A BREAK IN THE
CONVECTION THU NGT AS THE FRONT MOVES N-NE OF OUR FORECAST AREA
AND THE UPPER LEVEL TROUGH/LOW SHIFTS SE OF THE REGION. A MID LEVEL
VORT MAX MOVING E-SEWD THROUGH NRN MO MAY LEAD TO SCATTERED
CONVECTION ON FRI...ALTHOUGH IT APPEARS THAT THE GFS MODEL IS TOO
STRONG WITH THIS FEATURE AND OVERDONE WITH ITS QPF. THE UPPER
LEVEL RIDGE WILL BUILD BACK OVER THE CNTRL US FRI NGT INTO THE
WEEKEND. THIS ALONG WITH CONTINUED SLY SFC/LOW LEVEL FLOW WILL
LEAD TO WARMER HIGH TEMPERATURES WELL INTO THE 80S FOR THE
WEEKEND. THE GFS MODEL STILL APPEARS OVERDONE WITH ITS QPF...
ALTHOUGH THERE MAY BE ISOLATED TO WIDELY SCATTERED SHOWERS AND
STORMS MAINLY DURING THE AFTN INTO THE EARLY EVNG ON SAT. THE
POPS SHOULD BEGIN TO RAMP UP BEGINNING SUN AFTN...MAINLY ACROSS
NERN AND CNTRL MO AS SW FLOW SHORTWAVES AHEAD OF AN APPROACHING
UPPER LEVEL TROUGH MOVE NEWD THROUGH THIS REGION. THE MODELS
CONTINUE TO SLOW THE PROGRESSION OF THE UPPER LEVEL TROUGH/LOW
MOVING EWD THROUGH THE NRN PLAINS AND ITS ASSOCIATED COLD FRONT.
WE SHOULD SEE MORE WIDESPREAD AND ORGANIZED CONVECTION MON AND
MON NGT AHEAD OF THIS UPPER LEVEL TROUGH AND ASSOCIATED COLD
FRONT. THE COLD FRONT SHOULD FINALLY MOVE SEWD THROUGH OUR
FORECAST AREA TUE AND TUE EVNG WITH TEMPERATURES DROPPING BACK
DOWN TO SEASONAL NORMALS FOR TUE AND TUE NGT.

GKS

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1112 AM CDT WED MAY 15 2013

VFR CONDTIONS EXPECTED OUTSIDE OF CONVECTION. COLD FRONT CONTINUES
TO SLOWLY SINK SOUTH THIS MORNING AND WILL BECOME NEARLY
STATIONARY BY THIS AFTERNOON ACROSS FAR NORTHERN MISSOURI AND WEST
CENTRAL ILLINOIS. THIS IS THE MOST LIKELY AREAD FOR THUNDERSTORMS
TO DEVELOP LATE THIS AFTERNOON AND THIS EVENING. THIS WOULD HAVE
THE HIGHEST IMPACT ON KUIN TERMINAL. OTHERWISE AND
ELSEWHERE...ISOLATED CONVECTION COULD DEVELOP THIS AFTERNOON AND
EARLY THIS EVENING DUE TO DIURNAL HEATING. SOUTHWEST WIND TO
CONTINUE...WITH BRIEF WIND SHIFT AT KUIN POSSIBLE IF FRONT SINKS
THAT FAR SOUTH.

SPECIFICS FOR KSTL...
VFR CONDITIONS TO CONTINUE. CHANCES OF THUNDERSTORMS AFFECTING
TERMINAL TOO SMALL TO INCLUDE ANYTHING MORE THAN A VCTS IN
FORECAST AT THIS TIME. WEST/SOUTHWEST WIND TO CONTINUE THROUGH
FORECAST.

CVKING

&&

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

$$

WFO LSX