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000
FXUS63 KLSX 180455
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1155 PM CDT FRI MAY 17 2013

.UPDATE...
ISSUED AT 750 PM CDT FRI MAY 17 2013

EARLY THIS EVENING...ISOLATED SHRA SLOWLY DISSIPATING ACROSS THE
FA EARLY THIS EVENING...BUT WHERE WE MAY SEE THE DISSIPATION BE
THE MOST STUBBORN WILL BE IN NERN MO-W CNTRL IL WHERE AN UPPER
LEVEL DISTURBANCE IS SLOWLY WORKING ITS WAY THRU AND WILL MAINTAIN
SOME SORT OF LIFT IN A REGION OF SMALL CAPE. SFC TEMPS ARE IN THE
70S...BUT DWPT DEPRESSIONS ARE ALREADY 10F OR LESS FOR MANY
LOCATIONS AROUND STL METRO AND TO THE S AND E.

WILL MAINTAIN A TOKEN SLIGHT CHANCE OVER THE NRN FA INTO THE EARLY
PART OF THE OVERNIGHT WHILE ENDING ELSEWHERE BY 9PM. LOOK FOR
VSBYS TO BEGIN DROPPING BEGINNING LATE THIS EVENING BUT THE DROP
MAY NOT BE AS DRAMATIC GIVEN HOW WE ARE STILL DEALING WITH
EXTENSIVE CLOUD CIGS OVER THE AREA WHICH WILL MAKE THINGS DEVELOP
MORE SLOWLY. THEREFORE...FOR NOW...HAVE JUST ADDED IN PATCHY FOG.
ONCE THESE CLOUDS BREAK UP MORE WILL RE-EVALUATE...BUT LOOKS TO BE
WIDESPREAD 2-3SM VSBYS EXPECTED WITH POCKETS OF VSBYS BELOW 1SM WITH
LO CLOUD DEVELOPMENT AFTER MIDNIGHT.

MIN TEMPS STILL LOOK ON TARGET.

TES

&&

.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 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1137 PM CDT FRI MAY 17 2013

STILL EXPECTING IFR CIGS/VSBYS TO DEVELOP TONIGHT...THO IT SEEMS
LIKE IT`S TAKING A LITTLE LONGER THAN EXPECTED. JUST STARTING TO
SEE SOME VSBYS DROP INTO MVFR RANGE OVER THE PAST HOUR OR SO...AND
KFAM IS NOW DOWN TO 2SM. EXPECT THIS TREND TO CONTINUE...WITH MOST
OF THE AREA EXPERIENCING IFR CIGS/VSBYS BEFORE DAYBREAK SATURDAY
MORNING. LATEST MODEL GUIDANCE HAS BACKED OFF ON THE LOW END...SO
HAVE TWEAKED TAFS TO GO A BIT HIGHER AND DELAY THE ONSET OF IFR
CONDITIONS AS WELL. STILL EXPECTING FLIGHT CONDITIONS TO IMPROVE
TO VFR BY LATE MORNING ACROSS THE AREA.

SPECIFICS FOR KSTL...

STILL EXPECTING IFR CIGS/VSBYS TO DEVELOP AT LAMBERT TONIGHT...THO
IT SEEMS LIKE IT`S TAKING A LITTLE LONGER THAN EXPECTED. JUST
STARTING TO SEE SOME VSBYS DROP INTO MVFR RANGE IN THE STL METRO
AREA OVER THE PAST HOUR OR SO...AND KFAM IS NOW DOWN TO 2SM.
EXPECT THIS TREND TO CONTINUE...WITH THE VSBY DROPPING TO MVFR
BETWEEN 08Z AND 10Z...AND IFR CIGS DEVELOPING A LITTLE LATER AS WELL.
LATEST MODEL GUIDANCE HAS BACKED OFF ON THE LOW END...SO HAVE
TWEAKED THE TAF TO GO A LITTLE HIGHER THAN PREVIOUSLY FORECAST. STILL
EXPECTING FLIGHT CONDITIONS TO IMPROVE TO VFR BY LATE MORNING.

CARNEY

&&

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

$$

WFO LSX