Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 282053
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
353 PM CDT TUE JUL 28 2015

.SHORT TERM:  (THROUGH LATE TONIGHT)
ISSUED AT 349 PM CDT TUE JUL 28 2015

DANGEROUS HEAT INDICES ARE CURRENTLY IN THE 105-117F RANGE OVER
THE AREA WITH TEMPERATURES WELL INTO THE 90S. LAMBERT IS CURRENTLY
REPORTING 100. THESE VALUES SHOULD FALL OFF BELOW CRITERIA BY 9
PM. ISOLATED THUNDERTORMS ARE BEGINNING TO DEVELOP OVER THE AREA
AS ATMOSPHERE IS CURRENTLY UNCAPPED AND MLCAPES ARE BETWEEN
3000-4000 J/KG. ANY STORMS THAT DO DEVELOP THIS AFTERNOON MAY
BECOME STRONG AND MAY PRODUCE GUSTY WINDS AND HEAVY DOWNPOURS
BEFORE THE STORMS DIMINISH AROUND SUNSET. THERE WILL BE A BETTER
CHANCE OF STORMS LATER TONIGHT AS A COLD FRONT MOVES INTO THE
NORTHERN PART OF THE CWA. HAVE KEPT WITH BEST CHANCES OF
THUNDERSTORMS NORTH OF I-70 WHERE THERE WILL BE THE BEST
COMBINATION OF ASCENT FROM PASSING TROUGH TO THE NORTH WITH LOW
LEVEL MOISTURE CONVERGENCE.

.LONG TERM:  (WEDNESDAY THROUGH NEXT TUESDAY)
ISSUED AT 349 PM CDT TUE JUL 28 2015

(WEDNESDAY THROUGH FRIDAY)

HAVE EXTENDED THE HEAT WARNING FOR THE FAR SOUTHERN PART OF THE CWA
INTO THE TOMORROW AFTERNOON.  EVEN THOUGH THE COLD FRONT WILL MOVE
THROUGH THE AREA EARLY IN THE DAY...THERE WON`T BE A STRONG PUSH OF
COOLER AND DRIER AIR INTO SOUTHEAST MISSOURI AND SOUTHERN ILLINOIS
UNTIL WEDNESDAY NIGHT.  BECAUSE OF THIS, DEWPOINTS WILL STILL BE IN
THE MID 70S WITH HIGH TEMPERATURES CLIMBING INTO THE LOW 90S WHICH
WILL ALLOW HEAT INDEX READINGS TO CLIMB TO AROUND 105 DEGREES DURING
THE AFTERNOON.  COOLER AND DRIER WEATHER WILL MOVE INTO THE AREA FOR
THURSDAY AND FRIDAY.

SCATTERED THUNDERSTORMS WILL MOVE ACROSS WITH THE FRONT ON WEDNESDAY
MORNING.  THESE STORMS WILL BE MAINLY CONFINED ALONG AND SOUTH OF I-
44 IN MISSOURI AND ALONG AND SOUTH OF I-70 IN ILLINOIS DURING THE
AFTERNOON.  THURSDAY AND FRIDAY LOOK DRY AT THIS POINT.

(SATURDAY THROUGH TUESDAY)

ECMWF AND GFS CONTINUE TO ADVERTISE NORTHWESTERLY UPPER FLOW FOR EARLY
NEXT WEEK WITH A LARGE HIGH OVER THE SOUTHWESTERN CONUS AND LARGE
MEAN TROUGH OVER EASTERN NORTH AMERICA.  THE OPERATIONAL GFS BEGINS
TO FLATTEN THE FLOW OVER THE RIDGE BY TUESDAY WHEREAS THE ECMWF
KEEPS THE FLOW OVER MIDWEST MORE NORTHWESTERLY.  THE ECMWF HAS BEEN
MORE CONSISTENT AND HAS SUPPORT FROM THE GFS ENSEMBLE MEAN, SO WILL
KEEP WITH IT`S SOLUTION.  WILL KEEP WITH A DRY FORECAST OVER THE
WEEKEND INTO MONDAY AS HIGH PRESSURE MOVES ACROSS THE AREA.  BY LATE
ON TUESDAY A FRONT WILL BEGIN TO APPROACH THE AREA FROM THE NORTH
WHICH WILL INCREASE THUNDERSTORMS CHANCES AS THE ATMOSPHERE BECOMES
MORE UNSTABLE LATE IN THE DAY.  TEMPERATURES WILL BE CLOSE TO LATE
JULY NORMALS WITH 850MB TEMPERATURES BETWEEN 18-22C.

BRITT

&&

.AVIATION:  (FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1241 PM CDT TUE JUL 28 2015

PRIMARY CONCERN FOR THIS AFTERNOON IS THUNDERSTORM TRENDS. AT THIS
TIME, IT STILL LOOKS LIKELY THAT THERE WILL BE WIDELY SCATTERED
THUNDERSTORMS OVER MUCH OF EASTERN MISSOURI AND WESTERN ILLINOIS
THIS AFTERNOON. TIMING AND COVERAGE IS YET UNCERTAIN...BUT AM
BEGINNING TO NOTICE CUMULUS STARTING TO FORM OVER PARTS OF THE
OZARKS WHICH DOES BODE WELL FOR THUNDERSTORM DEVELOPMENT. STORMS
COULD BE STRONG WITH GUSTY WINDS AND VERY HEAVY RAIN, REDUCING THE
VISIBILITY TO IFR CONDITIONS. OTHERWISE EXPECT VFR FLIGHT
CONDITIONS TO CONTINUE. A COLD FRONT WILL MOVE INTO THE AREA
OVERNIGHT WHICH WILL BRING ANOTHER CHANCE OF THUNDERSTORMS WITH
POTENTIAL FOR LOWERED CONDITIONS AS WELL AS LOCALLY GUSTY WINDS.

SPECIFICS FOR KSTL:

PRIMARY CONCERN CONTINUES TO BE THE POSSIBILITY FOR THUNDERSTORMS
THIS AFTERNOON AT THE TERMINAL. THINK STORMS WILL DEVELOP OVER THE
EASTERN OZARKS LATER THIS AFTERNOON, WITH OUTFLOW BOUNDARIES
MOVING NORTH INTO THE METRO AREA TO PRODUCE ADDITIONAL STORMS
BETWEEN 21-00Z. TIMING AND COVERAGE IS STILL UNCERTAIN THOUGH SO I
DID NOT WANT TO HIT IT HARDER THAN VCTS AT THIS TIME. STORMS
SHOULD DISSIPATE DURING THE EARLY EVENING, AND EXPECT VFR
CONDITIONS TO PREVAIL FOR THE REST OF THE NIGHT INTO WEDNESDAY
MORNING. THERE WILL BE ANOTHER CHANCE OF STORMS DURING THE LATE
MORNING/AFTERNOON AS A COLD FRONT MOVES THORUGH THE AREA.

CARNEY

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...EXCESSIVE HEAT WARNING UNTIL 9 PM CDT THIS EVENING FOR BOONE MO-
     CALLAWAY MO-COLE MO-CRAWFORD MO-FRANKLIN MO-GASCONADE MO-
     JEFFERSON MO-LINCOLN MO-MONITEAU MO-MONTGOMERY MO-OSAGE MO-
     ST. CHARLES MO-ST. LOUIS CITY MO-ST. LOUIS MO-WARREN MO-
     WASHINGTON MO.

     EXCESSIVE HEAT WARNING UNTIL 9 PM CDT WEDNESDAY FOR IRON MO-
     MADISON MO-REYNOLDS MO-ST. FRANCOIS MO-STE. GENEVIEVE MO.

     HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR AUDRAIN MO-KNOX MO-
     LEWIS MO-MARION MO-MONROE MO-PIKE MO-RALLS MO-SHELBY MO.

IL...EXCESSIVE HEAT WARNING UNTIL 9 PM CDT THIS EVENING FOR CALHOUN
     IL-JERSEY IL-MADISON IL-MONROE IL-ST. CLAIR IL.

     EXCESSIVE HEAT WARNING UNTIL 9 PM CDT WEDNESDAY FOR RANDOLPH IL.

     HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR ADAMS IL-BOND IL-
     BROWN IL-CLINTON IL-FAYETTE IL-GREENE IL-MACOUPIN IL-MARION
     IL-MONTGOMERY IL-PIKE IL-WASHINGTON IL.

&&

$$

WFO LSX



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