National Weather Service Weather Forecast Office

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

000
FXUS63 KLSX 150458
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1158 PM CDT TUE MAY 14 2013

.UPDATE...
ISSUED AT 914 PM CDT TUE MAY 14 2013

FORECAST LOOKS ON TRACK AT THIS TIME. WIND IS STAYING FAIRLY
STRONG THIS EVENING WHICH IS KEEPING TEMPERATURES A LITTLE HIGHER
THAN PREVIOUSLY THOUGHT...BUT THERE`S STILL PLENTY OF TIME TO COOL
TONIGHT SO AM NOT ADJUSTING WEDNESDAY MORNING LOWS AT THIS TIME.
IF ANYTHING...MAY HAVE TO BUMP UP A COUPLE OF DEGREES...BUT MAJOR
CHANGES DO NOT APPEAR LIKELY.

CARNEY

&&

.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 320 PM CDT TUE MAY 14 2013

THE UNSEASONABLY WARM CONDITIONS WE WERE EXPECTING FOR THE LAST FEW
DAYS HAVE BEEN ON THE MARK TODAY WITH TEMPERATURES MORE TYPICAL OF
LATE JUNE/EARLY JULY. ST LOUIS HAS SET A RECORD SO FAR AT 92 DEGREES
AND THERE ARE STILL A FEW MORE HOURS OF HEATING TO GO. AS DISCUSSED
THE LAST FEW DAYS AS WELL...THE MODEL DEW POINT FORECASTS WERE WAY
OVERDONE. A MILD AND GENERALLY CLOUD-FREE NIGHT IS ON TAP AS LOW
LEVEL SOUTHWESTERLY FLOW PERSISTS.

GLASS

.LONG TERM...(WEDNESDAY THROUGH NEXT TUESDAY)
ISSUED AT 320 PM CDT TUE MAY 14 2013

THERE ARE SEVERAL FEATURES TO WATCH OUT FOR IN THE WED-THURS PERIOD
THAT WE HAVE BEEN DISCUSSING...FIRST THE ELONGATED SRN STREAM LOW
PRESSURE TROF CENTERED THROUGH EL PASO AND THE COLD FRONT NOW
STRETCHING FROM MINNESOTA THRU NW IOWA INTO NEBRASKA. THE GUIDANCE
IS IN PRETTY DECENT AGREEMENT WITH THE EAST-WEST FRONT BRINGING THE
FRONT INTO NRN MO-CENTRAL IL ON THURSDAY WHILE THE SRN STREAM
LOW/TROF RESULTS IN INCREASING MOISTURE. THE SURFACE DEW POINTS
ALONG/AHEAD OF THE FRONT STILL APPEAR TO BE OVERDONE GIVEN OBSERVATIONS
TODAY AND LOW LEVEL TRAJECTORIES FOR THE NEXT 24 HOURS. RATHER
THAN DEW POINTS IN THE UPPER 60S...LOWER 60S SEEMS MORE REALISTIC
WHICH WOULD YIELD MODERATE INSTABILITY WITH SBCAPES IN THE
2000-2500 J/KG RANGE RATHER THAT 3500+ AT PEAK AFTERNOON HEATING.
AT THIS TIME EXPECTING SCATTERED SHOWERS AND THUNDERSTORMS TO
DEVELOP IN THE ZONE ALONG/AHEAD OF THE FRONT IN RESPONSE TO
FRONTAL CONVERGENCE. I EXPECT THE COVERAGE OF STORMS TO DECREASE
AWAY FROM THE FRONTAL ZONE AND THINK THE MODELS ARE A BIT OVERDONE
WITH QPF EXTENT OWING TO THE OVERDONE INSTABILITY. I HAVE ALSO
GONE ON THE WARM SIDE OF GUIDANCE FOR HIGHS THINKING THERE WILL BE
QUITE A BIT OF SUN THROUGH THE FIRST HALF OF THE DAY.

THE HIGHEST POPS REMAIN IN THE VICINITY OF THE BOUNDARY WED NIGHT
INTO THURSDAY GIVEN IT IS THE PRIMARY FOCUS...BUT SCATTERED
ACTIVITY COULD OCCUR JUST ABOUT ANYWHERE GIVEN THE MIGRATING
SOUTHERN STREAM UPPER LOW/TROF. THE BOUNDARY ACTUALLY WAVERS NORTH
OF THE AREA BY THURSDAY AFTERNOON AND THE SOUTHERN STREAM UPPER
TROF WILL PASS TO THE EAST OF THE CWA AS WELL. THIS SHOULD RESULT
IN A DECREASING PROBABILITY OF CONVECTION LATE THURS/THURSDAY
NIGHT. ANOTHER WEAK LOW AMPLITUDE SHORT WAVE WILL TRACK ACROSS THE
TOP OF THE UPPER RIDGE ACROSS NORTHERN MO INTO WEST CENTRAL IL
FRIDAY/FRIDAY NIGHT BRINGING A BETTER CHANCE OF SHOWERS AND
THUNDERSTORMS TO NORTHERN SECTIONS OF THE CWA. IN THE WAKE OF THIS
FEATURE...HEIGHTS RISE ALOFT AS THE UPPER RIDGING INTENSIFIES ON
SATURDAY BRINGING WARMER TEMPERATURES. BEGINNING ON SUNDAY WE WILL
BEGING TO COME UNDER THE INFLUENCE OF A PROGRESSIVE UPPER TROF.
THE MODELS DIFFER ON THE STRUCTURE OF THE TROF WITH THE ECMWF
SHOWING MORE POSITIVE TILT. THESE VARIANCES IMPACT THE EASTWARD
COLD FRONT POSITION/MOVEMENT AND THE ASSOCIATED THUNDERSTORM
PROBABILTY...LONGEVITY AND ANY SEVERE WEATHER THREAT. CURRENT
INDICATIONS ARE THE THREAT OF SHOWERS AND THUNDERSTORMS SHOULD
RAMP UP CONSIDERABLY SUNDAY NIGHT INTO MONDAY.

GLASS

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1157 PM CDT TUE MAY 14 2013

VFR CONDITIONS WILL PREVAIL THRU THE VALID TAF PERIOD. DRY
CONDITIONS ARE ALSO EXPECTED THRU AT LEAST MIDDAY WEDNESDAY. A
CDFNT WILL EDGE INTO NEAR THE KUIN WEDNESDAY AFTERNOON AND IS
EXPECTED TO ULTIMATELY ACT AS A FOCUS FOR TSRA DEVELOPMENT BY LATE
AFTERNOON AND CONTINUE INTO THE EVENING. MAINTAINED VCTS AT THE
KUIN TAF DURING THIS TIME PERIOD. TSRA CHCS FOR THE OTHER TAF
SITES LOOKS MORE UP IN THE AIR AND HARD TO GET A FIRM HANDLE ON
FOR INCLUSION IN THE TAF AS THE COVERAGE SHOULD BE MORE SPARSE.
WHAT DOES DEVELOP S OF THE CDFNT LATE WEDNESDAY AFTERNOON SHOULD
DISSIPATE BY MID EVENING WITH LITTLE TO SUSTAIN IT. GUSTY SW SFC
WNDS WILL DIMINISH AROUND OR SHORTLY AFTER SUNSET. 50KT LO LEVEL
JET IN PROGRESS THE REST OF THE OVERNIGHT...AND LLWS WITH A LO
BASE JET AROUND 1100FT AND MAGNITUDE OF 40-45KTS OR MORE IS
JUSTIFIED.

SPECIFICS FOR KSTL...VFR THRU THE PERIOD...TSRA A POSSIBILITY LATE
WED AFTERNOON AND EARLY EVENING BUT PROBS TOO LO TO INCLUDE AT
THIS TIME...GUSTY SW SFC WNDS TO DIMINISH SHORTLY AFTER SUNSET...
LLWS ADDED WITH 40-45KT LO BASE JET MOVING THRU.

TES

&&

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

$$

WFO LSX