220 
FXUS63 KLSX 162314
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
614 PM CDT TUE JUL 16 2013

.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 259 PM CDT TUE JUL 16 2013

(THROUGH TONIGHT)

WHILE SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER 
SOUTHWESTERN MISSOURI THIS AFTERNOON...CONVECTION HAS STRUGGLED TO 
SURVIVE OVER THE EASTERN OZARKS AND CENTRAL MISSOURI DESPITE AMPLE 
CAPE AND DAYTIME HEATING. ANY STORMS THAT MANAGE TO SURVIVE OVER THE 
CWFA SHOULD QUICKLY DIMINISH ALONG WITH THE DIURNAL CLOUDCOVER 
WITHIN AN HOUR OR TWO OF SUNSET THIS EVENING YIELDING CLEAR SKIES 
AND LIGHT AND VARIABLE WINDS OVERNIGHT. LOW TEMPERATURES ARE 
EXPECTED TO BE IN THE LOWER 70S...WITH UPPER 60S POSSIBLE ACROSS THE 
EASTERN OZARKS AND MID 70S IN THE ST. LOUIS METRO AREA.

JP

.LONG TERM...(WEDNESDAY THROUGH NEXT TUESDAY)
ISSUED AT 259 PM CDT TUE JUL 16 2013

(WEDNESDAY - THURSDAY)

MID/UPPER LEVEL RIDGE WILL CONTINUE TO HOLD STRONG AND DOMINATE THE 
WX PATTERN THROUGH THE DAY ON THURSDAY. EVEN WITH A NEARLY 
VERTICALLY STACKED ANTICYCLONE OVER THE AREA AND ASSOCIATED 
LARGE-SCALE SUBSIDENCE...DUE TO ALMOST NO CAPPING IN PLACE EITHER 
AFTERNOON...HAVE KEPT SCH POPS FOR SHOWERS/STORMS ACROSS THE 
SOUTHERN HALF OF CWFA. BOTH DAYS WILL BE HOT AND HUMID WITH HIGHS IN 
THE LOW TO MID 90S AND AFTERNOON HEAT INDEX READINGS AROUND 100 
DEGREES. 

(FRIDAY - SATURDAY)

FRIDAY WILL LIKELY BE THE HOTTEST DAY OF THE YEAR AS 850-HPA TEMPS 
RISE ABOVE +20C. WIDESPREAD MID 90S ARE FORECAST WITH HEAT INDEX 
VALUES OF 100-105F. A COLD FRONT WILL APPROACH THE AREA FROM THE 
NORTHWEST OVERNIGHT FRIDAY AND INTO SATURDAY. AS PREVIOUS SHIFTS 
HAVE NOTED...THIS IS QUITE A BIT QUICKER THAN IT LOOKED A FEW DAYS AGO. 
HIGHS ON SATURDAY SHOULD BE ABOUT 5F COOLER THAN FRIDAY...AND MAY 
EVEN BE COOLER DEPENDING ON CLOUD COVER/PRECIPITATION. THUS...A HEAT 
ADVISORY PROBABLY WILL NOT BE IN THE OFFING AS SATURDAY WOULD LIKELY 
NEED TO BE THE 4TH DAY OF 100+ HEAT INDICES TO WARRANT AN
ADVISORY. HOWEVER...THE 105+ CRITERIA COULD BE MET ON FRIDAY IF
FORECAST HIGHS ARE WARMER OR DEWPOINTS ARE HIGHER. A WIDESPREAD
MODERATE- HEAVY RAINFALL EVENT LOOKS UNLIKELY AND CHC POPS STILL
SEEM WARRANTED FOR SATURDAY AS SFC CONVERGENCE ALONG THE FRONT
LOOKS FAIRLY WEAK AND BEST UPPER- LEVEL DYNAMICS STAY WELL TO THE
NORTHEAST TOWARD THE GREAT LAKES.

(SUNDAY - TUESDAY)

MEDIUM RANGE NWP GUIDANCE DIVERGES GREATLY BEHIND THE FRONT. GFS HAS 
A STRONGER/DEEPER UPPER-LEVEL TROUGH AND PUSHES THE FRONT ALL THE 
WAY INTO THE DEEP SOUTH WHILE THE ECMWF STALLS THE FRONT NEAR THE 
BOOTHEEL REGION. NEEDLESS TO SAY...NOT MUCH CONFIDENCE WITH RESPECT 
TO SENSIBLE WEATHER CONDITIONS IN THE SUNDAY THROUGH TUESDAY 
TIMEFRAME. IF THE GFS WERE TO BE BELIEVED...MUCH COOLER AND DRIER 
WEATHER WOULD BE IN STORE WITH HIGHS IN THE L/M 80S WHILE THE ECMWF 
WOULD CONTINUE POPS AND HAVE A VERY RAPID WARMUP WITH A HEAT WAVE 
BEGINNING EARLY NEXT WEEK. DID NOT DEVIATE FROM CR INIT WHICH LOOKED 
LIKE A NICE COMPROMISE BETWEEN THE TWO MODELS WITH REGARDS TO 
TEMPS/POPS.


GOSSELIN

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 611 PM CDT TUE JUL 16 2013

VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. DIURNAL CU AND
SPOTTY SHOWERS IN CENTRAL MO WILL DISSIPATE BY 01-02Z...WITH
REDEVELOPMENT OF DIURNAL CU BETWEEN 14-16Z ON WEDNESDAY. SURFACE
HIGH PRESSURE WILL DOMINATE BRINGING LIGHT AND VARIABLE WINDS.

SPECIFICS FOR KSTL...

VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. DIURNAL CU WILL
DISSIPATE BY 01Z...WITH REDEVELOPMENT OF DIURNAL CU BETWEEN
14-16Z ON WEDNESDAY. SURFACE HIGH PRESSURE WILL DOMINATE BRINGING
LIGHT AND VARIABLE WINDS.

GLASS

&&

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

$$

WFO LSX