Tuesday, September 7, 2010

Area Forecast Discussion - South Central/Southwest Missouri

FXUS63 KSGF 080016
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
716 PM CDT TUE SEP 7 2010

..MESOSCALE CONVECTIVE DISCUSSION...
..UPDATE TO AVIATION...

UPDATE...

SHOWERS AND A FEW THUNDERSTORMS HAVE DEVELOPED DURING THE LATE
AFTERNOON AND EARLY EVENING HOURS ACROSS SOUTHWEST MISSOURI. THESE
ARE EFFICIENT RAIN PRODUCERS WITH PRECIPITABLE WATER VALUES AROUND
1.75 INCHES. STORM MOTIONS ARE ALSO ONLY AROUND 10 KNOTS...SO
INCLUDED A FLASH FLOOD THREAT IN THE HAZARDOUS WEATHER OUTLOOK.

MODELS ARE NOT ALL THAT BULLISH ON QPF FOR THE REMAINDER OF
TONIGHT. NOT SO SURE THAT WILL BE THE CASE WITH A HANDFUL OF
LIFTING MECHANISMS COMING INTO PLAY. WE WILL CONTINUE TO HAVE THAT
FRONTAL BOUNDARY ACROSS SOUTHERN MISSOURI...WITH SHORT RANGE
MODELS ALSO INDICATING SOME WEAK PRESSURE ADVECTION DEVELOPING
LATER TONIGHT. WE WILL ALSO CONTINUE TO BE ON THE NORTHERN EDGE OF
MOISTURE TRANSPORT. HAVE THEREFORE INCREASED POPS TONIGHT ACROSS
SOUTHERN MISSOURI. WILL NEED TO CONTINUE WATCHING THE THREAT FOR
FLASH FLOODING AS PRECIPITABLE WATER VALUES APPROACHING 2.00
INCHES IMPINGE ON SOUTHERN MISSOURI. UPDATED PRODUCTS ALREADY
SENT.

SCHAUMANN

&&

DISCUSSION...

SHORT TERM (TONIGHT THROUGH TOMORROW NIGHT)...

SHOWERS AND A FEW THUNDERSTORMS THAT DEVELOPED ALONG 850 MB FRONT OVER
THE NORTHWESTERN CWA THIS MORNING HAVE SINCE DISSIPATED...WITH MORE
ORGANIZED SHRA/TSRA DEVELOPMENT IN NORTHERN ARKANSAS ALONG AND SOUTH
OF THE SFC FRONT. WITH FRONT ACROSS SOUTHERN CWA...WOULDN'T BE TOO
SURPRISED TO SEE A FEW SHOWERS AND THUNDERSTORMS DRIFT INTO THE
SOUTHERN HALF OF THE CWA THIS EVENING AND OVERNIGHT TONIGHT AS A
BROAD AND MODEST LOW LEVEL JET IMPINGES ON THE FRONT.

HEADING INTO WEDNESDAY...TROPICAL MOISTURE AHEAD OF HERMINE IS
EXPECTED TO BEGIN TO WORK NORTH INTO THE AREA. EXPECT AREAS OF
RAIN AND ISOLATED TSRA TO START TO MOVE INTO THE SOUTHWESTERN
PORTIONS OF THE FORECAST AREA TOMORROW MORNING...BEFORE GRADUALLY
EXPANDING NORTHEAST DURING THE DAY. COULD SEE SOME PRETTY HEALTHY
QPF OVER FAR EASTERN KANSAS AND SW MISSOURI LATE WEDNESDAY AS
REMNANTS OF HERMINE GET CLOSER...BEFORE MAIN BULK OF RAIN ARRIVES
ON THURSDAY.

WITH RAIN EXPECTED TO PICK UP IN COVERAGE AND INTENSITY WEDNESDAY
NIGHT...FLASH FLOOD WATCH WAS STRONGLY CONSIDERED FOR PORTIONS OF
THE CWA. AFTER DISCUSSION...FELT THAT BEST BET WAS TO HOLD OFF FOR
ONE MORE RUN OF MODEL GUIDANCE BEFORE MAKING FINAL CALL ON FLOOD
HEADLINES. CURRENT GUIDANCE IS CERTAINLY SUGGESTIVE THAT HEADLINES
WILL EVENTUALLY BE NEEDED OVER ESPECIALLY THE NORTHWESTERN PORTIONS
OF THE CWA...BUT UNCERTAINTY REMAINS IN EXACT TRACK AND STRENGTH OF
SYSTEM...AS WELL AS EVENTUAL QPF AMOUNTS. FLOOD THREAT WILL CONTINUE
TO BE MENTIONED IN THIS AFD PRODUCT AS WELL AS HWO.

BOXELL

LONG TERM (THURSDAY THRU TUESDAY)...

THE REMNANTS OF TS HERMINE WILL CONTINUE TO WORK ITS WAY THROUGH THE
OZARKS INTO EARLY FRIDAY MORNING. WITH A SIGNIFICANT AMOUNT OF
MOISTURE FLUX CONTINUING TO BE SUGGESTED BY THE MODELS AHEAD OF
HERMINE'S ARRIVAL AND GOOD DIVERGENCE ALOFT...HEAVY RAIN CONCERNS
WILL BE VERY REAL INTO THURSDAY. SOME UNCERTAINTY REMAINS IN THE
INTERACTION BETWEEN THE REMNANTS OF HERMINE AND THE APPROACHING
MIDLEVEL TROUGH SO HAVE BEEN SOMEWHAT CONSERVATIVE IN THE QPF FOR
FRIDAY. IT WOULD NOT BE SURPRISING FOR SOME AREAS TO RECEIVE 2 IN OR
MORE OF RAIN ON THURSDAY AFTERNOON BUT THE EXACT LOCATION COULD
STILL SHIFT.

WHILE NOT THE MAIN CONCERN FOR THIS AREA AT THIS TIME...THE
POTENTIAL FOR SEVERE STORMS ON THURSDAY AFTERNOON MUST BE
CONSIDERED. THE PROGGED TRACK OF HERMINE CURRENTLY PUTS THE OZARKS
IN THE RIGHT FRONT QUADRANT THURSDAY BEFORE TRULY TRANSITIONING TO
AN EXTRA-TROPICAL CYCLONE. THIS AREA IS CLIMATOLOGICALLY PREFERRED
FOR SEVERE STORM DEVELOPMENT DUE TO SUBSTANTIAL HELICITY AND
MODERATE INSTABILITY VALUES. THE 12Z RUN OF THE GFS IS MORE ON THE
WORST CASE SCENARIO SEVERE WEATHER SIDE OF THINGS AND HAS CAPE
VALUES OVER SGF AND JLN NEAR 2000 J/KG AT 21Z THURSDAY WITH
HELICITY VALUES RANGING FROM 470 TO 740 M^2/S^2. IF HERMINE SHOULD
MAINTAIN STRENGTH INLAND...THIS COULD BE A SIGNIFICANT CONCERN. AT
THIS POINT THOUGH...HAVE TRENDED TOWARD THE ECMWF SOLUTION WHICH
WEAKENS HERMINE AND POINTS TO HEAVY RAIN AS THE MAIN CONCERN FOR
THE SGF AREA.

THIS WEEKEND INTO NEXT WEEK...A SHORT REPRIEVE FROM THE RAIN WILL
ARRIVE ON FRIDAY BEFORE ANOTHER FRONT MOVES THROUGH ON SATURDAY
MORNING FOLLOWED BY A 500MB SHORTWAVE THAT PUSHES THROUGH AND BRINGS
MORE RAIN EARLY NEXT WEEK. A 500MB RIDGE LOOKS TO REBUILD OVER
SOUTHERN TEXAS DURING THE WEEKEND AND WILL HELP KEEP DRIER NW FLOW
OVER THE REGION AND PREVENT THE PASSING FRONT AND SHORTWAVE FROM
MAKING TOO MUCH SOUTHERN HEADWAY.

CROWE

&&

AVIATION...

SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL REMAIN POSSIBLE
ACROSS SOUTHERN MISSOURI FOR THE REMAINDER OF TONIGHT. CEILINGS
WILL CONTINUE TO HOVER RIGHT AROUND 3 KFT...PUTTING CONDITIONS
RIGHT AT THE EDGE OF MVFR THRESHOLDS. EXPECT A BRIEF BOUT OF IFR
CONDITIONS WITH ANY HEAVIER SHOWERS THAT PASS OVER THE TERMINALS.
MAY ALSO SEE SOME LIGHT FOG LATER TONIGHT...ESPECIALLY AT KBBG.
RAIN COVERAGE WILL THEN INCREASE ON WEDNESDAY...SO HAVE MAINTAINED
PREVAILING RAIN SHOWERS AND MVFR CONDITIONS.

SCHAUMANN

&&

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

$$

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