Severe Thunderstorm Warning 253, NWS St. Louis, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
115 PM CDT THU AUG 19 2004

.DISCUSSION...

A SLOW MOVING COLD FRONT SAGGING SOUTHWARD ACROSS BISTATE REGION
DURING THE MORNING HAS NOW BECOME STATIONARY ACROSS THE OZARKS
REGION...ALIGNING FROM NEAR SPRINGFIELD MISSOURI TO JUST SOUTH OF
THE ST. LOUIS METRO AREA NORTHEAST TO MATTOON ILLINOIS. BKN
STRATUS NORTH OF THE FRONT HAS KEPT TEMPERATURES 10 TO 20 DEGREES
BELOW NORMAL (LOW TO MID 60S)...WHILE TO THE SOUTH ABUNDANT SUNSHINE
HAS ALLOWED TEMPERATURES TO CLIMB INTO THE MID AND UPPER 80S.

AN AREA OF LOW PRESSURE IS FORECAST TO RIDE NORTHEAST ALONG THE
FRONTAL BOUNDARY TONIGHT AND FRIDAY. THE POTENTIAL OF HVY RAINFALL
EXISTS TONIGHT AND TOMORROW MORNING ACROSS THE AREA. ETA CONTINUES
TO KEEP BEST QPF ACROSS NORTHERN HALF OF MISSOURI...WHILE GFS QPF
BULLSEYE IS ALIGNED ACROSS CENTRAL CWA. AT THIS TIME IT SEEMS
REASONABLE THAT BEST CHANCES OF PRECIPITATION WILL BE ALONG AND
SOUTH OF FRONTAL BOUNDARY...WHERE BEST INSTABILITY AND DYNAMICS WILL
EXIST.

AS HIGH PRESSURE BUILDS ACROSS THE CENTRAL UNITED STATES THIS
WEEKEND...ONE CAN EXPECT ANOTHER COOLER THAN NORMAL WEEKEND WITH
HIGH TEMPERATURES IN THE LOWER 80S UNDER A MOSTLY SUNNY SKY.

A PATTERN CHANGE ALOFT IS INDEED FORECAST BY ALL MODELS TO START
TAKING SHAPE BY THE END OF THIS WEEKEND AND CONTINUE THROUGH EARLY
NEXT WEEK. UNCERTAINTY IN THE EXTENDED PERIOD FOCUSES AROUND THE
AMPLITUDE AND PROGRESSION OF THE MID LEVEL TROF THAT IS FORECAST TO
DIG ACROSS THE WESTERN CONUS. THE GFS AND UKMET KEEP THE TROF
PROGRESSIVE AND LESS AMPLIFIED...WHILE THE ECMWF DIGS THE TROF SOUTH
TO THE THE BAJA OF CALIFORNIA.  OBVIOUSLY THE AMPLITUDE OF THE TROF
OUT WEST WILL DICTATE THE STRENGTH OF THE RIDGE THAT WILL BUILD
ACROSS THE EASTERN CONUS. ULTIMATELY...TEMPERATURES WILL BE ON THE
RISE THROUGH THE EXTENDED PERIOD WITH LITTLE CHANCE OF SIGNIFICANT
PRECIPITATION...OR IN SIMPLER TERMS...SUMMER RETURNS TO THE MIDWEST.
&&

.LSX WATCHES/WARNINGS/ADVISORIES...

MO...NONE.
IL...NONE.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ST LOUIS MO
400 PM CDT THU AUG 19 2004

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-201200-
ADAMS IL-AUDRAIN-BOND IL-BOONE-BROWN-CALHOUN IL-CALLAWAY-CLINTON IL-
COLE-CRAWFORD-FAYETTE IL-FRANKLIN-GASCONADE-GREENE IL-IRON-JEFFERSON-
JERSEY IL-KNOX-LEWIS-LINCOLN-MACOUPIN IL-MADISON-MADISON IL-MARION-
MARION IL-MONITEAU-MONROE-MONROE IL-MONTGOMERY-MONTGOMERY IL-OSAGE-
PIKE-PIKE IL-RALLS-RANDOLPH IL-REYNOLDS-SHELBY-ST CHARLES-
ST CLAIR IL-ST FRANCOIS-ST LOUIS-ST LOUIS CITY-STE GENEVIEVE-WARREN-
WASHINGTON-WASHINGTON IL-
400 PM CDT THU AUG 19 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND EASTERN MISSOURI
AS WELL AS SOUTHWEST ILLINOIS.

.DAY ONE...TONIGHT

SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP
ACROSS THE AREA TONIGHT...STORMS WILL BECOME MORE NUMEROUS
LATE THIS EVENING INTO THE OVERNIGHT HOURS.

IN ADDITION THERE IS A THREAT FOR LOCALLY HEAVY RAINFALL ACROSS
NORTHEAST AND CENTRAL MISSOURI AS WELL AS WEST CENTRAL ILLINOIS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

A STRONG SYSTEM WILL CONTINUE TO MOVE EAST ACROSS OUR AREA ON FRIDAY
CONTINUING THE THREAT FOR THUNDERSTORMS AND LOCALLY HEAVY RAINFALL
FOR THE ENTIRE AREA.  THESE HAZARDS WILL DIMINISH FRIDAY EVENING AS
THE SYSTEM PULLS AWAY TO THE EAST.  THUNDERSTORMS ARE NOT EXPECTED
TO REACH SEVERE LIMITS.

.SPOTTER ACTIVATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TONIGHT.