Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 311722
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1222 PM CDT MON AUG 31 2015

.SHORT TERM:  (THROUGH LATE THIS AFTERNOON)
ISSUED AT 326 AM CDT MON AUG 31 2015

THREAT OF CONVECTION REMAINS THE PRIMARY QUESTION MARK FOR TODAYS
FORECAST.  MODEL GUIDANCE OVER THE LAST FEW DAYS HAS NOT OFFERED ANY
CLEAR ANSWERS TO THIS QUESTION...AND UNFORTUNATELY THE SIGNALS IN
THIS MORNINGS GUIDANCE ISN`T MUCH MORE DEFINITIVE.

OVERNIGHT WATER VAPOR IMAGERY INDICATES MID LEVEL SHEAR AXIS PARKED
FROM THE ARKLATEX REGION INTO THE LOWER GREAT LAKES...WITH THE
ANIMATION OF THE IMAGERY INDICATING A WEAK CIRCULATION CENTER HAS
WORKED ITS WAY NE FROM WESTERN AR TO JUST EAST OF UNO BY 08Z.
MEANWHILE...SUBTLE DRYING OVER S IL SUGGESTS SOME VERY WEAK
SHORTWAVE MIGRATING SW THRU STL AREA ON THE NORTH SIDE OF THE SHEAR
AXIS.  OBVIOUSLY THIS IS A FAIRLY CHAOTIC UA PATTERN, AND SINCE
FEATURES ARE FAIRLY WEAK MODELS ARE HAVING A TOUGH TIME RESOLVING
SENSIBLE WEATHER TRENDS.

HOWEVER...ALMOST ALL GUIDANCE...INCLUDING THE HI-RES EXPLICIT
OUTPUT...SUGGESTS SOME THREAT OF CONVECTION OVER SOUTHEAST SECTIONS
OF THE CWA TODAY.  WHILE CURRENT RADAR DATA INDICATES NO PRECIP
IN/NEAR OUR AREA WOULD NOT BE SURPRISED TO SEE SOME SUNRISE SURPRISE
OVER THE NEXT FEW HOURS AHEAD OF UPPER LOW AS IT SPINS ITS WAY INTO
SOUTHERN IL (WHICH SEEMS TO BE A TREND HINTED AT BY MUCH OF THE HI-
RES GUIDANCE)...WITH ADDITIONAL SPOTTY STORMS ATTEMPTING TO FLAIR UP
DURING THE HEAT OF THE AFTERNOON IN THE VICINITY OF THE SHEAR AXIS.
FOR NOW HAVE PRIMARY FOCUS OF AFTERNOON DEVELOPMENT OVER S IL AND SE
MO IN THE VICINITY OF THE AFOREMENTIONED SHEAR AXIS.

SLOW MOVING STORMS COULD ONCE AGAIN POSE A THREAT OF SPOTTY HEAVY
DOWNPOURS...SIMILAR TO THE STORM THAT PRODUCED 2.57" @ KFAM ON
SUNDAY AFTERNOON/EVENING.

HIGHS TODAY SHOULD BE SIMILAR TO THOSE OF YESTERDAY.

TRUETT

.LONG TERM:  (TONIGHT THROUGH SUNDAY)
ISSUED AT 326 AM CDT MON AUG 31 2015

EVEN THOUGH SHEAR AXIS WILL SHIFT FURTHER SOUTHEAST, COULD STILL SEE
SOME ISOLATED ACTIVITY THIS EVENING, BUT CONFIDENCE IS LOW SO KEPT
MENTION OUT FOR NOW. DAY CREW WILL NEED TO KEEP AN EYE OUT.
OTHERWISE, WARMER WEATHER IS EXPECTED THROUGH THE REST OF THE
FORECAST PERIOD WITH HIGHS IN THE UPPER 80S TO LOW 90S AND OVERNIGHT
LOWS IN THE UPPER 60S TO LOW 70S.

AS WE GET INTO THE HOLIDAY WEEKEND, UPPER LEVEL RIDGE BEGINS TO
WEAKEN ALLOWING NEXT WEATHER SYSTEM TO MOVE CLOSER TO FORECAST AREA.
WILL SEE AN INCREASE IN LOW LEVEL MOISTURE AND INSTABILITY BY SUNDAY
SO KEPT SLIGHT CHANCE POPS IN FOR PORTIONS OF THE FORECAST AREA.

BYRD

&&

.AVIATION:  (FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1208 PM CDT MON AUG 31 2015

ISOD TSRA ARE POSSIBLE AGAIN THIS AFTERNOON. HOWEVER...WITH
VERY LOW CHANCES OF IMPACTING A TERMINAL...HAVE KEPT TAFS DRY FOR
NOW. LATEST GUIDANCE SUGGESTS CU FIELD THIS AFTERNOON MAY BECOME
BKN RATHER THAN SCT. WILL CONTINUE TO MONITOR TRENDS. TSRA ARE
POSSIBLE AGAIN AROUND SUNRISE TUES MORNING...BUT ARE CURRENTLY
EXPECTED TO REMAIN E OF UIN/SUS/CPS. OTHERWISE...WINDS WILL BECOME
SWLY TUES MORNING WITH SCT CU FORMING WITH BASES AROUND 5 KFT.

SPECIFICS FOR KSTL: ISOD TSRA MAY DEVELOP THIS AFTERNOON. CU FIELD
MAY BECOME BKN THIS AFTN BUT SUBSIDENCE FROM THIS MORNINGS CONVECTION
MAY LIMIT THIS. TSRA ARE POSSIBLE AGAIN TUES MORNING AROUND
SUNRISE...BUT ARE EXPECTED TO REMAIN E OF TERMINAL.
OTHERWISE...WINDS WILL BECOME SWLY TUES MORNING WITH SCT CU
FORMING WITH BASES AROUND 5 KFT.

TILLY

&&

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

$$

WFO LSX



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