Flash Flood Watch 10, NWS Birmingham, AL

065 
WGUS64 KBMX 222135
FFABMX

FLOOD WATCH
NATIONAL WEATHER SERVICE BIRMINGHAM AL
335 PM CST THU DEC 22 2011

...HEAVY RAINS HAVE MOVED OUT OF THE NORTHWESTERN ALABAMA...

ALZ011>015-022-222245-
/O.CAN.KBMX.FF.A.0010.000000T0000Z-111223T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MARION-LAMAR-FAYETTE-WINSTON-WALKER-PICKENS-
INCLUDING THE CITIES OF...HAMILTON...SULLIGENT...VERNON...
FAYETTE...DOUBLE SPRINGS...JASPER...CARROLLTON
335 PM CST THU DEC 22 2011

...FLASH FLOOD WATCH IS CANCELLED...

THE FLASH FLOOD WATCH FOR PORTIONS OF CENTRAL ALABAMA...NORTHWEST
ALABAMA AND WEST CENTRAL ALABAMA HAS BEEN CANCELLED. THE MAIN LINE
OF HEAVY RAINS HAVE NOW MOVED INTO EASTERN ALABAMA...WITH LITTLE
RAIN EXPECTED IN THE WESTERN HALF OF THE AREA.

$$

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
547 AM CST THU DEC 22 2011

.UPDATE...
FOR AVIATION.

&&

.DISCUSSION...

STATIONARY FRONT CLEARLY EVIDENT ON SURFACE OBSERVATIONS THIS
MORNING CUTTING ACROSS ALABAMA...ROUGHLY FROM JUST SOUTH OF
ANNISTON TO JUST SOUTH OF DEMOPOLIS. IN FACT...THE FRONT MAY NOW
ACTUALLY BE DRIFTING NORTHWARD AS A WARM FRONT. RADAR IMAGERY
SHOWS A LARGE MASS OF RAIN AND THUNDERSTORMS TO OUR WEST. THOSE
STORMS SO FAR THIS MORNING HAVE BEEN LARGELY ON THE COLD SIDE OF
THE FRONT...WITH UPDRAFTS ROOTED ABOVE THE BOUNDARY LAYER. THIS
RAIN MASS WAS AHEAD OF AN APPROACHING UPPER LEVEL SHORTWAVE
TROUGH...PROGGED TO SWING ACROSS THE GULF COAST STATES TODAY.

INITIAL CHALLENGE FOR TODAY IS TRYING TO DETERMINE SEVERE WEATHER
RISK ACROSS OUR AREA. THE AIR MASS SOUTH OF THE FRONT IS QUITE
JUICY...ESPECIALLY CONSIDERING WE ARE NOW JUST BEYOND THE WINTER
SOLSTICE. DEWPOINTS IN THE LOWER TO MID 60S RAISE EYEBROWS. THE
APPROACHING SHORTWAVE SHOULD PROVIDE AN AMPLE AMOUNT OF LIFT...
ALTHOUGH THE MODELS DO SHOW THE SHORTWAVE BECOMING ELONGATED AND
LOSING SOME OF ITS STRENGTH WITH TIME. AS WE GET INTO THE
AFTERNOON...SBCAPES ARE FORECAST TO CLIMB INTO THE 500 TO 800 J/KG
RANGE ACROSS THE SOUTHERN COUNTIES. THIS...COUPLED WITH 50 TO 60
KTS OF 0-6 KM BULK SHEAR...SUGGESTS THAT THERE CERTAINLY IS THE
POSSIBILITY FOR STORMS TO BECOME ORGANIZED ENOUGH TO BECOME
SEVERE. AS THE SURFACE LOW ASSOCIATED WITH THE UPPER LEVEL TROUGH
RIDES ALONG THE FRONT...IT WILL LIKELY BRING AN ENHANCEMENT TO THE
LOW LEVEL INFLOW AND RELATED ENHANCEMENT OF THE LOW LEVEL SHEAR
PROFILE. SO HAVING SAID ALL THE ABOVE...IF THE MODEL SUGGESTED
SURFACE BASED INSTABILITY CAN BE REALIZED (WHICH IS CONDITIONAL ON
THE RAIN SHIELD STAYING IN ON THE NORTHERN SIDE OF THE FRONT AND
ALLOWING THE WARM SECTOR TO REMAIN...WELL...WARM)...THEN THE
THREAT OF SEVERE THUNDERSTORMS (INCLUDING A FEW SUPERCELLS)
BECOMES A BIT MORE SIGNIFICANT. WILL DEFINITELY NEED TO WATCH
CONDITIONS LOCALLY...AND DEVELOPMENTS TO OUR WEST...THROUGH THE
MORNING HOURS.

RAIN AND STORMS SHOULD EXIT THE AREA TONIGHT...PROVIDING A BRIEF
DRY PERIOD FOR CENTRAL ALABAMA. HOWEVER...ACTIVE FLOW REGIME WILL
CONTINUE FOR THE SOUTHEAST STATES THROUGH THE HOLIDAY WEEKEND.
ANOTHER SHORTWAVE TROUGH IS FORECAST TO BRING OVERRUNNING RAINS TO
THE AREA SATURDAY NIGHT INTO SUNDAY. THOSE HOPING FOR A REPEAT OF
LAST YEAR'S WHITE CHRISTMAS (FOR SOME) WILL LIKELY BE
DISAPPOINTED...AS CONDITIONS AT THIS POINT LOOK A BIT TOO WARM FOR
ANYTHING BUT A COOL/COLD RAIN.

FORECAST CONFIDENCE TAKES A BIG NOSEDIVE FROM MONDAY THROUGH THE
END OF THE PERIOD...DUE TO INCREASING DIFFERENCES AMONG THE
VARIOUS MODELS...AS WELL AS RUN TO RUN DIFFERENCES WITH EACH
PARTICULAR MODEL. WILL USE A BLEND OF GFS AND ECMWF FOR NOW.

/61/

&&

.AVIATION...
12Z TAF DISCUSSION.

FRONT STALLED ACROSS CENTRAL ALABAMA THIS MORNING EXPECTED TO ONLY
DRIFT A LITTLE NORTH TODAY AS LOW PRESSURE TO THE WEST MOVES RAPIDLY
EASTWARD ALONG IT.  WIDESPREAD IFR TO MVFR CIGS AND VSBYS PREVAIL
ACROSS THE AREA TODAY AND DO NOT EXPECT MUCH IMPROVEMENT DURING THE
FORECAST PERIOD.  LOOK FOR RAIN TO BEGIN OVERSPREADING AREA BY MID
MORNING WITH TSRA DEVELOPING BY LATE MORNING/EARLY AFTERNOON.  TSRA
NOT EXPECTED TO BE WIDESPREAD ALTHOUGH SOME COULD BE STRONG AND
TIMING AT ANY TAF SITE NEXT TO IMPOSSIBLE AT THIS TIME SO HAVE JUST
INCLUDED VCTS IN TAFS.  DAY SHIFT MAY BE ABLE TO GET BETTER HANDLE
ON TIMING AND LOCATION.  LOW PRESSURE SHOULD DRAG THE FRONT EAST OF
THE AREA BY EARLY TONIGHT BUT EXPECT IFR TO MVFR CIGS TO CONTINUE
OVERNIGHT IN ITS WAKE.

41

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BIRMINGHAM AL
545 AM CST THU DEC 22 2011

ALZ011>015-017>050-231045-
AUTAUGA-BARBOUR-BIBB-BLOUNT-BULLOCK-CALHOUN-CHAMBERS-CHEROKEE-
CHILTON-CLAY-CLEBURNE-COOSA-DALLAS-ELMORE-ETOWAH-FAYETTE-GREENE-HALE-
JEFFERSON-LAMAR-LEE-LOWNDES-MACON-MARENGO-MARION-MONTGOMERY-PERRY-
PICKENS-PIKE-RANDOLPH-RUSSELL-SHELBY-ST CLAIR-SUMTER-TALLADEGA-
TALLAPOOSA-TUSCALOOSA-WALKER-WINSTON-
545 AM CST THU DEC 22 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE COUNTIES SERVED BY THE
NATIONAL WEATHER SERVICE OFFICE IN BIRMINGHAM.

.DAY ONE...TODAY AND TONIGHT.

THERE IS A CHANCE THAT A FEW SEVERE STORMS MAY DEVELOP ACROSS
CENTRAL ALABAMA TODAY. THE STRONGEST STORMS MAY BE CAPABLE OF
PRODUCING DAMAGING STRAIGHT LINE WINDS...AND POSSIBLY A TORNADO. AT
THIS TIME...THE GREATEST POTENTIAL FOR SEVERE STORMS WILL BE BETWEEN
10 AM AND 6 PM...WITH THE BEST CHANCES EXPECTED TO BE SOUTH AND EAST
OF A LINE FROM NEAR PICKENSVILLE TO JASPER.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT MAY BECOME
NECESSARY TODAY.