Friday, September 24, 2010

Area Forecast Discussion - South Central/Southwest Missouri

FXUS63 KSGF 241135
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
635 AM CDT FRI SEP 24 2010

..UPDATE TO AVIATION...

DISCUSSION...
/ISSUED 235 AM CDT FRI SEP 24 2010/

A NARROW BAND OF MODERATE TO HEAVY RAIN SHOWERS HAS DEVELOPED
AHEAD OF AN ADVANCING COLD FRONT ON THE NORTHWEST EDGE OF THE
FORECAST AREA EARLY THIS MORNING. THE SHOWERS WERE FORMING WITHIN
A FETCH OF DEEPER MID LEVEL MOISTURE EVIDENCED BY WATER VAPOR
IMAGERY WHICH SHOWED A PLUME CONNECTED TO THE TROPICS BUT TAKING A
RATHER LONG WAY ACROSS NORTHERN MEXICO AND WEST TEXAS BEFORE
REACHING THE OZARKS. THE 00Z SOUNDING FROM TOPEKA WHICH SAMPLED
THE AIR MASS WELL SHOWED PRECIPITABLE WATER VALUES OVER TWO INCHES.
OVER THE PAST COUPLE OF HOURS...CLOUD TOPS HAVE COOLED SLIGHTLY
BUT OVERALL RAIN INTENSITIES HAVE BEEN LESS THAN IMPRESSIVE. THE
COLD FRONT HAS BEEN MAKING FAIRLY STEADY EASTWARD PROGRESS AND HAS
CLEARED BOURBON...VERNON AND ST. CLAIR COUNTIES...SO WE PLAN TO
REMOVE THESE AREAS FROM THE GOING FLASH FLOOD WATCH. WE WILL BE
MAKING A LAST MINUTE CALL ON OTHER COUNTIES TO REMOVE BASED ON
SATELLITE/RADAR TRENDS OVER THE NEXT HOUR OR SO.

OVERALL TRENDS IN THE FORECAST FOR THE SHORT TERM WILL BE TO
MAKE SOME MINOR ADJUSTMENTS TO TIMING OF ENDING PRECIP FROM WEST
TO EAST...AND WIND SHIFT ALONG THE ADVANCING COLD FRONT. THE
CURRENT PLAN IS TO SPEED BOTH THE FROPA AND PRECIP ENDING UP A
BIT BUT WILL CONTINUE TO MONITOR RADAR TRENDS.

A DECENT COOL DOWN IS STILL EXPECTED OVER THE WEEKEND AS AN UPPER
LEVEL TROUGH DIGS SOUTHEASTWARD ACROSS THE NORTHERN PLAINS AND
UPPER MIDWEST THROUGH SATURDAY AND THEN DROPS SOUTHWARD INTO
MISSOURI SATURDAY NIGHT AND SUNDAY MORNING. NAM/GFS/ECMWF ARE ALL
GENERATING SOME LOWER END PRECIP AMOUNTS WITH THIS FEATURE IN
ADDITION TO TRANSPORTING A REINFORCING SHOT OF CANADIAN AIR AND
DROPPING TEMPERATURES INTO THE UPPER 40S AND LOWER 50S SUNDAY
MORNING. WILL INCLUDE ISOLATED THUNDER WITH THIS FEATURE AS COOLER
TEMPS ALOFT MAY DESTABILIZE THE AREA ENOUGH FOR A FEW
THUNDERSTORMS TO DEVELOP.

THE ECMWF BRINGS ANOTHER SLUG OF LIGHT PRECIP OVER THE AREA SUNDAY
NIGHT AND EARLY MONDAY. FOR NOW WILL KEEP SOME LOWER CHANCES OVER
OUR SOUTHEAST COUNTIES SINCE THEY WILL BE CLOSER TO THE CENTER OF
THE CLOSED LOW...AND KEEP A LITTLE EXTRA CLOUD COVER ELSEWHERE TO
ACCOUNT FOR PERIOD SPOKES OF ENERGY ROTATING AROUND THE BACK SIDE
OF THE UPPER TROUGH.

&&

AVIATION...
/ISSUED 616 AM CDT FRI SEP 24 2010/

MVFR CEILINGS WILL LIKELY IMPACT AREA TERMINALS EARLY THIS MORNING
AS COLD FRONT MOVES ACROSS THE AREA. IMPROVING FLIGHT CONDITION
CAN BE EXPECTED DURING THE MORNING AS DRIER AIR FILTERS INTO THE
AREA. LOW LEVEL WIND SHEAR WILL IMPACT THE AREA EARLY THIS
MORNING. OTHERWISE SURFACE WINDS WILL SHIFT TO THE NORTHWEST THE
COLD FRONT MOVES EAST OF THE AREA.

FOSTER

&&

SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

$$


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