000
FXUS63 KLSX 162323
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
623 PM CDT THU MAY 16 2013

.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 334 PM CDT THU MAY 16 2013

SO FAR THIS AFTERNOON...CONVECTION HAS PRIMARILY BEEN LOCATED OVER
CENTRAL MO IN ADVANCE OF SHORTWAVE ROTATING WWD AROUND THE N SIDE OF
THE UPPER LEVEL LOW...WHICH IS CURRENTLY LOCATED OVER NW AR.
ACTIVE CONVECTION IS ALSO OCCURRING ALONG STALLED FRONTAL BOUNDARY
AND REMNANT OUTFLOW FROM EXTREME SE IA INTO CENTRAL IL...JUST
OUTSIDE OF OUR CWA.

TSRA CHANCES OVER THE NEXT FEW HOURS WILL BE SHIFTING TO S SECTIONS
OF THE CWA...AND TO NEAR THE VICINITY OF THE E-NE DRIFTING UPPER
LEVEL LOW...FOR MOST OF THE EVENING AND INTO THE OVERNIGHT HOURS.
FOR NOW I`VE USED A FAIRLY BROAD BRUSH APPROACH FOR POPS.  ITS
CERTAINLY POSSIBLE THAT THE N EDGE OF THE POP GRADIENT ISN`T TIGHT
ENOUGH...BUT GIVEN THE UNCERTAINLY ON WHERE THE N EDGE WILL SET UP
THIS SHOULD LEAVE SOME WIGGLE ROOM FOR NOWCAST-TYPE TWEEKS DURING
THE EVENING/OVERNIGHT BASED ON RADAR TRENDS.  HIGHEST POPS WILL BE
OVER OUR FAR S COUNTIES...IN THE HIGH CHANCE RANGE...WITH ADDITIONAL
REFINEMENT CERTAINLY POSSIBLE BASED ON RADAR TRENDS.

TEMPS SHOULD BE BOTTOMING OUT IN THE 60S OVER MOST OF THE AREA.

TRUETT

.LONG TERM...(FRIDAY THROUGH NEXT THURSDAY)
ISSUED AT 334 PM CDT THU MAY 16 2013

(FRIDAY THROUGH SUNDAY)

UPPER LEVEL LOW CONTINUES TO WEAKEN AND LIFT OUT OF FORECAST AREA ON
FRIDAY. STILL HAVE DECENT INSTABILITY AND LIFT...SO WILL SEE
SCATTERED SHOWERS AND THUNDERSTORMS OVER SOUTHEAST MO CONTINUE TO
DEVELOP AND SPREAD NORTH ACROSS REST OF THE REGION...WITH BEST
CHANCES OVER EASTERN HALF OF FORECAST AREA. AS FOR HIGH TEMPS...MID
70S TO LOW 80S IS EXPECTED.

SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS MAINLY FRIDAY EVENING FOR
AREAS ALONG AND EAST OF MISSISSIPPI RIVER. OTHERWISE...DRY AND MILD
CONDITIONS TO PERSIST WITH LOWS IN THE LOW TO MID 60S.

STILL DEALING WITH WEAKENING UPPER LEVEL SYSTEM THAT WILL BE OVER
THE OHIO VALLEY BY SATURDAY. COULD SEE SCATTERED SHOWERS AND
THUNDERSTORMS OVER FAR EASTERN PORTIONS OF FORECAST AREA ON BACKSIDE
OF SYSTEM DURING THE DAY ON SATURDAY. OTHERWISE...DRY CONDITIONS FOR
MOST LOCATIONS THROUGH SATURDAY NIGHT. HIGHS WILL BE IN THE LOW TO
MID 80S...WITH LOWS IN THE MID TO UPPER 60S SATURDAY NIGHT.

ON SUNDAY...NEXT WEATHER SYSTEM APPROACHES AREA...BUT MODELS
CONTINUE TO SLOW THIS SYSTEM DOWN. SO BACKED OFF ON POPS A
BIT...WITH LOW CHANCE POPS OVER CENTRAL/NORTHEAST MO...WEST CENTRAL
IL. HIGHS ON SUNDAY WILL REMAIN MILD IN THE MID TO UPPER 80S.

(SUNDAY NIGHT THROUGH THURSDAY)

SLOWLY INCREASED POPS FROM WEST TO EAST SUNDAY NIGHT AND MONDAY AS
COLD FRONT MOVES CLOSER TO THE AREA. BOTH 12Z GFS AND ECMWF NOW HAVE
FRONT PROGGED TO NOT SLIDE THROUGH FORECAST AREA TIL LATE IN THE DAY
ON TUESDAY. SO INCREASED POPS FOR PORTIONS OF THE FORECAST AREA ON
TUESDAY AND TUESDAY NIGHT. AS FOR CHANCE OF SEVERE WEATHER ON MONDAY
AFTERNOON AND EVENING...STILL POSSIBLE AS THERE IS DECENT MU
CAPES...LOW LEVEL MOISTURE AND SHORTWAVE ENERGY...SO WILL KEEP
MENTION IN HWO.

BEYOND THAT...PCPN TO TAPER OFF ON WEDNESDAY...WITH ANOTHER CHANCE
FOR SHOWERS AND THUNDERSTORMS ON THURSDAY AS NEXT SYSTEM APPROACHES
REGION FROM THE SOUTHWEST.

HIGHS NEAR NORMAL IN THE MID TO UPPER 70S TUESDAY THROUGH
THURSDAY...WITH LOWS EACH NIGHT IN THE MID 50S TO LOW 60S.

BYRD

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 622 PM CDT THU MAY 16 2013

WIDELY SCT TSRA NEAR KUIN MOVING AWAY FROM THAT TERMINAL AND
SHOULD DISSIPATE WITHIN THE NEXT COUPLE HOURS...NO IMMINENT THREAT
TO KUIN. AREAS OF UNRESTRICTED VSBY SPRINKLES APPROACHING STL
METRO FROM THE S AND WITH OB SITES INDEED REGISTERING PCPN
REACHING THE GROUND...HAVE ADDED IN A COUPLE HOURS AS A TEMPO FOR
ALL STL METRO TAF SITES. OTHERWISE...LO CIGS ASSOCIATED WITH MORE
OF THE CORE OF THE UPPER LEVEL SYSTEM TO OUR SW WILL EDGE CLOSER
TO CNTRL MO AND STL METRO LATE TONIGHT AND THEN GET SHUNTED OFF TO
THE E...AUGMENTED ON FRIDAY BY DIURNAL INFLUENCES...WITH CLEARING
EXPECTED HEADING INTO FRIDAY EVENING...FOR A TIME. MAY TRIP IFR
CIGS AT KCOU AND STL METRO SITES LATE TONIGHT AND EARLY FRIDAY
MORNING BUT FOR NOW WILL LEAVE OUT AND MONITOR. A BETTER LO
STRATUS AND FOG SETUP APPEARS TO EXIST ON FRIDAY NIGHT...
ESPECIALLY FOR STL METRO SITES...AS MOISTURE NEVER REALLY GETS
SCOURED OUT BEHIND SYSTEM AND WITH SOME CLEARING EXPECTED AND
LIGHT WINDS. ANOTHER ROUND OF SCT TSRA APPEARS IN THE OFFING
FRIDAY AFTERNOON AS UPPER LEVEL SYSTEM WILL STILL BE CLOSE ENOUGH.

SPECIFICS FOR KSTL...VFR CONDITIONS UNTIL LATE TONIGHT WITH SOME
SPRINKLES EARLY ON...DETERIORATING CONDITIONS EXPECTED LATE
TONIGHT AND EARLY FRIDAY MORNING WITH IFR POSSIBLE BUT FOR NOW
HAVE FAVORED THE LO-END MVFR OF THE PREVIOUS TAF...IMPROVEMENT TO
CIGS ABOVE 2KFT EXPECTED ON FRIDAY WITH PARTIAL CLEARING AND
PERHAPS ANOTHER ROUND OF LO STRATUS AND FOG FRIDAY NIGHT. BEST
PCPN CHCS AFTER EARLY THIS EVENING WILL BE FRIDAY AFTERNOON WITH
TSRA DEVELOPING WITH THE HEATING OF THE DAY.

TES

&&

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

$$

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