Area Forecast Discussion
Issued by NWS St. Louis, MO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLSX 282234
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
534 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 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 524 PM CDT TUE JUL 28 2015

WHAT APPEARS TO BE A GRAVITY WAVE MOVED SOUTHEAST ACROSS EASTERN
MO AS A RESULT OF THE CONVECTION OVER IOWA TODAY. THE CU WOULD
ENHANCE ON THE SATELLITE IMAGERY AS IT MOVED, FINALLY KICKING UP A
FEW THUNDERSTORMS OVER THE STL AREA. NEXT FEATURE WILL BE A COLD
FRONT THAT WILL MOVE ACROSS THE AREA OVERNIGHT AND ON WEDNESDAY.
LOOKS LIKE A SHIFT TO THE NW AT UIN ABOUT 10Z, COU 12Z AND INTO
THE STL AREA 14Z. PLENTY OF INSTABILITY BUT FORCING LOOKS WEAK.
UIN LOOKS TO HAVE THE BEST SHOT AT THUNDER OVERNIGHT. OUTLFOW WILL
MESS WITH THE WIND AT SUS FOR A WHILE BEFORE SETTLING BACK TO
LIGHT SOUTH.

SPECIFICS FOR KSTL: OUTFLOW FROM STORMS IN IL HAS SHIFTED THE WIND
TO THE SE. THIS MAY LAST FOR A COUPLE OF HOURS BUT WILL GO BACK TO
LIGHT SOUTHERLY. WILL HAVE TO KEEP AN EYE ON THE RADAR TO SEE IF
MORE STORMS FORM ALONG THE OUTFLOW, SO A VCTS FOR A COUPLE OF
HOURS SOUNDS PRUDENT. LOOKS LIKE THE FRONT INTIALLY MOVES IN ABOUT
12Z WITH A WEST WIND THEN TO NW ABOUT 14Z. FORCING LOOKS WEEK IN
THE MORNING SO WILL GO DRY FOR NOW BUT WOULD NOT BE SURPRISED TO
SEE THAT CHANGE. DAYTIME HEATING IN THE AFTERNOON AND THE FRONT IN
THE NEIGHBORHOOD COULD KICKED OFF STORMS MONDAY AFTER 18Z. A VCTS
LOOKS TO BE THE WAY TO GO FOR NOW.

JPK

&&

.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


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.