Friday, September 24, 2010

Area Forecast Discussion - South Central/Southwest Missouri

FXUS63 KSGF 240735
AFDSGF

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

DISCUSSION...

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.

TERRY
&&

AVIATION...

FOR THE 06Z TAFS...RAIN HAS BEEN SLOWER TO PUSH INTO THE CWA THIS
EVENING BUT WAS BEGINNING TO SHIFT INTO THE WESTERN CWA AS OF 04Z.
ALMOST NO LIGHTNING DETECTED ON LDS. WILL STILL SEE POCKETS OF
HEAVIER RAINFALL DURING THE OVERNIGHT BUT HAVE TAKEN THUNDER OUT
OF THE TAFS FOR NOW. WILL KEEP PREDOMINANT VISIBILITY IN THE VFR
RANGE WITH A 4 HOUR TEMPO GROUP OF MVFR VISIBILITY. EXPECTING
CEILINGS WITH THE RAIN AND INITIALLY BEHIND THE FRONT TO BE IN THE
MVFR RANGE. CLEARING SHOULD TAKE PLACE BY MID TO LATE MORNING AT
ALL 3 LOCATIONS.

LINDENBERG

&&

SGF WATCHES/WARNINGS/ADVISORIES...
MO...FLASH FLOOD WATCH UNTIL 10 AM CDT THIS MORNING FOR MOZ055>058-
068>071-077>081-088>091-093>095-101>103.

KS...FLASH FLOOD WATCH UNTIL 10 AM CDT THIS MORNING FOR KSZ101.

&&

$$


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