National Weather Service Weather Forecast Office

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

000
FXUS63 KLSX 162037
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
337 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 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1235 PM CDT THU MAY 16 2013

BELIEVE GREATEST COVERAGE OF CONVECTION THIS AFTERNOON WILL BE IN
UIN AREA...WHERE BEST HEATING/INSTABILITY WILL CO-EXIST IN VICINITY OF
FRONTAL BOUNDARY AND/OR RESIDUAL OUTFLOW FROM LAST NIGHTS
CONVECTION. AMS-TYPE ACTIVITY CERTAINLY POSSIBLE FURTHER S TO THE
I-70 CORRIDOR...BUT BELIEVE THAT THESE STORMS WILL BE MUCH MORE
HIT AND MISS. OUTSIDE OF A TSRA THREAT AT SUS FOR THE NEXT 30-45
MIN OR SO BASED ON LATEST DEVELOPMENT...WILL KEEP COU AND STL AREA
TAFS DRY FOR THE AFTERNOON/EARLY EVENING HOURS. OUTSIDE OF STORMS
EXPECTING A SCT-BKN CU DECK 4-5KFT...WITH BROADER RAIN SHIELD
ASSOCIATED WITH UPPER LOW REMAINING S OF ALL TAF SITES.

WITH LOW LEVEL MOISTURE SPIRALLING AROUND LOW...IN THE STL AREA
HAVE CONTINUED TREND OF EARLIER FORECASTS OF INTRODUCING MVFR CIGS
DURING THE PREDAWN HOURS.  HAVE TRIED TO BE A BIT MORE OPTIMISTIC
AT UIN AND COU...WITH CIGS ALSO DROPPING BUT REMAINING LOW END
VFR.

SPECIFICS FOR KSTL...CURRENT ACTIVITY IN THE METRO AREA WILL MISS STL
TAF TO THE WEST. WHILE CAN`T TOTALLY RULE OUT ADDITIONAL
DEVELOPMENT THIS AFTERNOON...DUE TO ITS SPOTTY NATURE WILL KEEP
STL TAF DRY ATTM AND NOWCAST THIS THREAT AS NEEDED.  OTHERWISE...
EXPECTING A BKN CU DECK 4-5KFT INTO THE EVENING...WITH MVFR CIGS
DEVELOPING DURING THE PREDAWN HOURS.

TRUETT
&&

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

$$
WFO LSX