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000
FXUS63 KLSX 172354
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
654 PM CDT FRI MAY 17 2013

.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 306 PM CDT FRI MAY 17 2013

SHOWERS HAVE CONTINUED TO PERCOLATE NORTHWARD ACROSS THE CWA THIS
AFTERNOON AS A SLOW MOVING UPPER LOW CONTINUES TO DRIFT TOWARD THE
OHIO VALLEY. WHILE NO REPORTS HAVE BEEN RECEIVED...CANNOT RULE OUT A
RUMBLE OF THUNDER WITH SOME OF THE STRONGER STORMS THIS AFTERNOON
AND THIS EVENING...THOUGH OVERALL EXPECT THE ACTIVITY TO WANE WITH
THE LOSS OF DIURNAL HEATING AND DIMINISH FROM WEST TO EAST AS THE
LOW CONTINUES TO MOVE EAST.

DEWPOINTS TODAY HAVE RISEN TO THE LOW TO MIDDLE 60S AND SHOULD HOLD
IN THE LOW 60S OVERNIGHT. THE COMBINATION OF CALM TO LIGHT WINDS AND
PLENTY OF BOUNDARY LAYER MOISTURE YIELDS CONCERN FOR FOG DEVELOPMENT
TONIGHT. THIS MORNING...OBSERVATIONS IN KANSAS...OKLAHOMA...AND EXTREME
SOUTHWEST MISSOURI INDICATED WIDESPREAD FOG...AND GIVEN THIS AIRMASS
WILL BE MOVING EASTWARD TONIGHT...CANNOT IGNORE THE POTENTIAL FOR
FOG TO DEVELOP DURING THE EARLY OVERNIGHT HOURS. FORECAST SOUNDINGS
INDICATE GREATER POTENTIAL FOR FOG GENERALLY ALONG AND SOUTH OF THE
I-70 CORRIDOR...THOUGH CANNOT RULE OUT SOME LIGHT FOG OR HAZE NEAR
DAYBREAK FOR THE NORTHERN TIER OF THE CWA.

OTHERWISE...AFTER PRECIPITATION TAPERS OFF THIS EVENING ACROSS THE
AREA...A TRANQUIL NIGHT IS EXPECTED WITH OVERNIGHT LOW TEMPERATURES
IN THE LOW TO MIDDLE 60S...SLIGHTLY ABOVE NORMAL FOR THIS TIME OF
YEAR.

PHILLIPSON

.LONG TERM...(SATURDAY THROUGH NEXT FRIDAY)
ISSUED AT 306 PM CDT FRI MAY 17 2013

REMNANTS OF UPPER LEVEL LOW OVER THE OHIO VALLEY COULD STILL
BRING SOME ISOLATED SHOWERS AND A FEW THUNDERSTORMS TO FAR EASTERN
PORTIONS OF FORECAST AREA ON SATURDAY. OTHERWISE...SHOULD SEE MORE
SUNSHINE AND WITH WINDS FROM THE SOUTHEAST TO SOUTH...TEMPERATURES
TO WARM UP INTO THE LOW TO MID 80S.

MILD WEATHER TO PERSIST SATURDAY NIGHT WITH LOWS ONLY IN THE MID TO
UPPER 60S. THERE IS A CHANCE FOR SOME SCATTERED SHOWERS AND A FEW
THUNDERSTORMS LATE...AS A WEAK WARM FRONT LIFTS NORTHWARD THROUGH
FORECAST AREA.

BY SUNDAY...NEXT WEATHER SYSTEM TO APPROACH REGION WITH WINDS
PICKING UP FROM THE SOUTH...GUSTS TO NEAR 25 MPH AT TIMES. LOW LEVEL
MOISTURE WILL BE ON THE INCREASE WITH SOME DECENT CAPES IN THE WARM
SECTOR...SO SHOWERS AND THUNDERSTORMS POSSIBLE...MAINLY OVER
CENTRAL/NORTHEAST MO...WEST CENTRAL IL. HIGHS WILL BE IN THE MID 80S
TO NEAR 90.

AS HAS BEEN THE CASE THE PAST COUPLE OF MODEL RUNS...THE FORWARD
SPEED OF THIS SYSTEM HAS SLOWED DOWN...AS UPPER LEVEL LOW SITS AND
SPINS OVER THE UPPER MIDWEST. SO PCPN WILL SLOWLY INCREASE FROM WEST
TO EAST SUNDAY NIGHT AND MONDAY...BEST CHANCES WITH THIS SYSTEM WILL
BE MONDAY NIGHT AND TUESDAY. CURRENT TIMING HAS FRONT NOT MOVING
THROUGH TIL LATE TUESDAY...EARLY WEDNESDAY...SO PCPN TO LINGER
ACROSS MOST OF FORECAST AREA TIL WEDNESDAY. AS FOR SEVERE CHANCES
WITH THIS SYSTEM...STILL HAVE DECENT CAPES...STRONG DEEP LAYER SHEAR
AND MOISTURE BEGINNING SUNDAY AFTERNOON THROUGH MONDAY EVENING...SO
PORTIONS OF THE FORECAST AREA ARE OUTLOOKED FOR A CHANCE OF SEVERE
WEATHER THROUGH THIS PERIOD.

AS FOR TEMPS...WILL SEE HIGHS IN THE 80S ON MONDAY...EVENTUALLY
COOLING DOWN INTO THE 70S EVERYWHERE THURSDAY AND FRIDAY. LOWS TO
DROP INTO THE 50S BY WEDNESDAY NIGHT AND THURSDAY NIGHT.

BYRD

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 641 PM CDT FRI MAY 17 2013

FEW REMAINING SHOWERS SHOULD DISSIPATE QUICKLY OVER THE NEXT
HOUR...AND AM EXPECTING VFR FLIGHT CONDITIONS TO PREVAIL AT
LEAST INTO EARLY EVENING. EXPECT SOME MVFR FOG TO DEVELOP DURING
THE LATE EVENING...OR EARLY OVERNIGHT HOURS AND STRATUS TO
DEVELOP AFTER THAT. COMBINATION OF IFR STRATUS AND FOG WILL LIKELY
PREVAIL AFTER 07-08Z ACROSS THE AREA THROUGH SUNRISE. EXPECT
CIGS/VSBYS TO GRADUALLY RISE TO HIGH MVFR/VFR BY 14-15Z SATURDAY MORNING.

SPECIFICS FOR KSTL...

EXPECT THE FEW REMAINING SHOWERS TO DISSIPATE QUICKLY THROUGH 01Z.
VFR FLIGHT CONDITIONS WILL PREVAIL AT LEAST THROUGH THE EARLY
EVENING...BUT AM EXPECTING FOG/STRATUS TO DEVELOP LATER TONIGHT.
THINK STRATUS WILL BE THE PRIMARY PROBLEM WITH CIGS BETWEEN
300-500FT FOR LAMBERT TONIGHT...WITH THICKER FOG REMAINING WEST OF
THE TERMINAL. HOWEVER...CANNOT RULE OUT DENSE FOG AND STRATUS WHICH
COULD BRING FLIGHT CONDITIONS DOWN TO AIRPORT MINIMUMS. SHOULD SEE
GRADUAL IMPROVEMENT IN CIGS/VSBYS AFTER 13-14Z SATURDAY MORNING
WITH HIGH-END MVFR/VFR CLOUDS PREVAILING BY LATE MORNING/EARLY AFTERNOON.


CARNEY

&&

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

$$

WFO LSX