Special Weather Statement, NWS Birmingham, AL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
835 PM CDT TUE MAR 29 2011

.UPDATE...MESOSCALE UPDATE.

&&

.DISCUSSION...

MODEL SUITE PERFORMANCE OVER THE PAST FEW DAYS HAS NOT EXACTLY HAD A
GREAT HANDLE ON THE DEVELOPING SENSIBLE WEATHER THIS EVENING. THE
LATEST WATER VAPOR IMAGERY HAS AN UPPER TROUGH SWINGING INTO THE
SOUTHERN PLAINS WHILE SEVERAL SHORT WAVE TROUGHS RIDE THROUGH THE
SUBTROPICAL JET FLOW INTO THE GULF COAST REGION. SYNOPTIC SCALE LIFT
IS INCREASED AS THE UPPER TROUGH APPROACHES. BOTH THE RUC AND GFS
DEVELOP ENHANCED MESOSCALE LIFT ACROSS CENTRAL ALABAMA BY 1 AM BUT
IT APPEARS THE RUC MASS FIELDS ARE CLOSER TO 01Z OBSERVATIONS.
295K-300K ISENTROPIC SURFACES INDICATE DECENT LIFT AND CONVERGENCE
OVER SOUTHERN MISSISSIPPI AND LOUISIANA THAT WILL TRANSLATE INTO THE
WESTERN HALF OF CENTRAL ALABAMA BY 06Z. THE 00Z RAOB INDICATES WE
ARE MOISTURE STARVED RIGHT NOW BUT THE LOW LEVEL JET BETWEEN 2K-5K
FT WILL INCREASE TO 30 TO 35 KTS OUT OF THE SOUTHWEST AND USHER IN
PLENTY OF MOISTURE. RUC SOUNDINGS FOR WESTERN ALABAMA HAVE A
DECIDEDLY DIFFERENT LOOK THAN MODEL SOUNDINGS THE PAST FEW DAYS.
THERE WILL BE A PERIOD BEFORE SATURATION WHERE -10 TO -30 CAPE
VALUES REACH SEVERAL HUNDRED AND THIS WOULD SUPPORT SOME HAIL
PRODUCTION. SPC MESOANALYSIS HAS A CHANCE OF ELEVATED SUPERCELLULAR
STRUCTURE INTO NORTH CENTRAL MISSISSIPPI AT THIS TIME WITH
SUFFICIENT SHEAR FOR THIS ORGANIZATION. THEREFORE...HAVE ADDED THE
WESTERN THIRD OF THE AREA TO SEVERE STORM OUTLOOK...WITH LARGE HAIL
FOR THE OVERNIGHT HOURS. CONDITIONS WILL BECOME LESS FAVORABLE
EASTWARD...BUT SOME SMALL HAIL MAY STILL BE POSSIBLE.

AS THE SURFACE MOISTURE INCREASES OVERNIGHT AND A WEAK SURFACE LOW
LIFTS A WARM FRONT INTO SOUTHERN ALABAMA...THERE IS A SMALL CHANCE
THAT SOME SURFACE BASED STORMS MAY BE INITIATED IN FAR SOUTHWESTERN
AREAS GENERALLY SOUTH OF A EUTAW TO SELMA LINE. THIS WOULD ENABLE A
SMALL CHANCE OF DAMAGING WINDS AND TORNADOES IN THIS AREA...BUT
CONFIDENCE ON THE NORTHWARD PUSH OF THE MOISTURE BAND IS NOT GREAT.

RADAR DEPICTIONS WEST OF THE AREA HAVE INDICATED SEVERAL SPLITTING
STORMS WITH LEFT MOVERS BECOMING PROMINENT HAIL PRODUCERS. WILL
MONITOR THE DEVELOPMENT CLOSELY OVERNIGHT ESPECIALLY FOR ANY STORMS
THAT APPEAR ROOTED IN THE SURFACE LAYER.

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&&

.AVIATION...00Z TAF DISCUSSION.

WITH THE APPROACH OF A SHORT WAVE AND SURFACE LOW DEVELOPING ALONG
THE NORTHERN GULF COAST TONIGHT...EXPECT SHOWERS AND THUNDERSTORMS
TO AFFECT THE AREA. WATCHING DEVELOPMENT BACK TO OUR WEST IN
SOUTHWEST MS AND NORTHEAST LA. SHOWERS ARE EXPECTED TO MOVE INTO
ALABAMA JUST BEFORE MIDNIGHT AND SPREAD ACROSS THE AREA. AIRMASS
OVER CENTRAL ALABAMA IS RATHER STABLE AT THE SURFACE GIVEN THE WARM
FRONT IS STILL DOWN ALONG THE COAST. THINK THE BEST CHANCE FOR
THUNDER WILL BE AT MGM AND TOI...BUT TS CANNOT BE RULED OUT IN THE
NORTH. CONFIDENCE IS TOO LOW TO INCLUDE AT THOSE TERMINALS AT THIS
TIME. CANT RULE OUT A SHOWER OR THUNDERSTORM EARLIER THAN
FORECASTED...AND WILL HAVE TO AMEND AS NEEDED.

CLOUDS WILL REMAIN LOW ACROSS THE AREA OVERNIGHT...AND LIKELY
THROUGH MUCH OF TOMORROW. SHOWERS WILL BECOME WIDESPREAD OVERNIGHT
BECOMING A BROAD AREA OF MODERATE RAINFALL WED MORNING AHEAD OF A
COLD FRONT. EXPECT RAIN TO END AND WINDS TO SHIFT TO THE NORTHWEST
AROUND MIDDAY IN THE NORTH. EXPECT LOW CLOUDS TO REMAIN ACROSS THE
AREA BEHIND THE FRONT.

NOTICE...KEET TAF WILL HAVE (AMD LTD TO VIS WIND AND WX) AMENDED TO
THE END OF THE FORECAST UNTIL FURTHER NOTICE. THE CEILOMETER DATA
WILL BE GOING THROUGH NUMEROUS TESTS AND MONITORED FOR ACCURACY.

14

&&

.PREV DISCUSSION...
/ISSUED AT 324 PM CDT TUE MAR 29 2011/.

CURRENTLY LAYING IN WAIT...WATCHING THE WARM FRONTAL BOUNDARY THAT
HAS REALLY ESTABLISHED ITSELF OVER THE NORTH CENTRAL GULF. FOR
THE MOST PART DON'T EXPECT THAT WE WILL SEE ITS EFFECTS UNTIL MUCH
LATER...IF AT ALL. HAVE A DISTINCT FEELING THAT IT WILL STRUGGLE
TO LIFT NORTHWARD WITH TIME...EVEN AS THE SURFACE LOW TRACKS
ACROSS THE SOUTHERN HALF OF THE AREA. THE CLOUDS AND DRIZZLE
CONDITIONS HAVE REALLY ACTED TO KEEP THE WEDGE AND EASTERLY FLOW
FIRMLY IN PLACE TODAY. IN OTHER WORDS...THINK THE MODELS ARE BEING
RATHER AGGRESSIVE IN BRINGING THE FRONT NORTHWARD WITH
TIME...MUCH THE SAME AS HAVING THE TEMPERATURES 5 TO 10 DEGREES
TOO WARM FOR THIS AFTERNOON. MOST LIKELY DUE TO THE VERTICAL
RESOLUTION AND SHALLOW CLOUD COVER. NONETHELESS...WILL LEAVE A FEW
COUNTIES IN THE DEEP SOUTHWEST WITH THE CHANCE OF SEEING A SEVERE
STORM...POSSIBLY ELEVATED...HAIL AND DAMAGING WINDS AS THE MAIN
THREATS. THERE IS SOME LOW LEVEL SHEAR...AND I SUPPOSE THERE COULD
BE AN OUTSIDE TOR THREAT...BUT JUST DON'T THINK WE HAVE THE LOW
LEVEL INSTABILITY TO SUSTAIN LASTING UPDRAFTS. IT MAY BE RATHER
CLOSE...HOWEVER.

THE THREAT SHOULD LINGER THROUGH THE LATE MORNING HOURS TOMORROW
ALONG THE SOUTHEASTERN COUNTIES AS THE WARM FRONT AND NOW COLD FRONT
MOVE ACROSS THE SOUTHERN CWA. AGAIN...THE MAIN THREATS STILL LOOK TO
BE WIND AND HAIL...AS THE COLD FRONT OVERTAKES THE WARM
SECTOR...MAINLY SOUTH AND EAST OF MGM. THE RAIN COULD BE MODERATE
ACROSS MUCH OF THE NORTH IN AN OVER RUNNING SCENARIO...WITH THE GULF
COAST CONVECTION KEEPING A REASONABLE CHECK ON OUR MOISTURE.

BEYOND TOMORROW AFTERNOON...WE WILL GET A MUCH NEEDED BREAK WITH
JUST SOME UPPER LEVEL TROF SHOWERS POSSIBLE ON THURSDAY AND MAYBE
OVER THE WEEKEND THOUGH I LEFT IT OUT OF THE FORECAST...OTHERWISE
NORTHWEST FLOW IS EXPECTED TO DOMINATE THROUGH THE LATE WEEKEND.
THIS WILL GIVE US QUIETER CONDITIONS...WITH THE NEXT REAL WEATHER
THREAT SHAPING UP FOR EARLY NEXT WEEK. TEMPERATURES WILL ALSO
REMAIN NEAR NORMAL..BUT WILL BEGIN TO REBOUND BY SUNDAY AND MONDAY
AS GULF RETURN FLOW CRANKS UP AHEAD OF SAID NEXT SYSTEM...WHICH
SHOULD BE ON OUR DOORSTEP BY TUESDAY.

17/KLAWS

&&

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

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BIRMINGHAM AL
800 PM CDT TUE MAR 29 2011

ALZ011>015-017>050-301130-
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-
800 PM CDT TUE MAR 29 2011

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

.DAY ONE...TONIGHT.

THERE WILL BE A THREAT OF SEVERE THUNDERSTORMS PRODUCING LARGE HAIL
GENERALLY WEST OF A LINE FROM DOUBLE SPRINGS AND JASPER...TO
CENTREVILLE AND SELMA. THE STORMS WILL BE POSSIBLE MUCH OF THE
OVERNIGHT HOURS. ADDITIONALLY...THERE WILL BE A SMALL THREAT OF
DAMAGING WINDS AND TORNADOES FOR AREAS GENERALLY SOUTH OF A LINE
FROM EUTAW TO SELMA AFTER MIDNIGHT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

SHOWERS AND THUNDERSTORMS WILL LINGER INTO WEDNESDAY AFTERNOON...
MAINLY FOR THE EXTREME SOUTHEASTERN COUNTIES OR ALONG AND SOUTH OF
THE INTERSTATE 85 CORRIDOR. THERE IS A SMALL THREAT OF LARGE
HAIL AND DAMAGING WINDS THROUGH THE 1 OR 2 PM.

.SPOTTER INFORMATION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT MAY BECOME
NECESSARY TONIGHT THROUGH MID DAY WEDNESDAY FOR THE THREAT OF SEVERE
WEATHER.

75

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1001 PM CDT TUE MAR 29 2011

ALZ030-031-300345-
GREENE AL-SUMTER AL-
1001 PM CDT TUE MAR 29 2011

...SIGNIFICANT WEATHER ADVISORY FOR GREENE AND SUMTER COUNTIES UNTIL
1045 PM CDT...

AT 1001 PM CDT...THE NATIONAL WEATHER SERVICE WAS TRACKING A STRONG
THUNDERSTORM NEAR BOYD...OR 8 MILES NORTHWEST OF YORK...MOVING EAST
AT 35 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER IS EXPECTED WITH THIS STORM...
ALONG WITH FREQUENT DANGEROUS LIGHTNING.

LOCATIONS IN OR NEAR THE PATH OF THIS STORM INCLUDE...
  YORK...
  LIVINGSTON...
  EUTAW...
  BOYD...
  EMELLE...

THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND
TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS... FOR ADDITIONAL
INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.

&&

LAT...LON 3298 8835 3299 8817 3303 8817 3310 8791
      3280 8782 3276 8787 3276 8781 3272 8783
      3271 8779 3265 8777 3264 8781 3260 8776
      3230 8833 3230 8842 3231 8843
TIME...MOT...LOC 0301Z 252DEG 29KT 3260 8835

75

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1033 PM CDT TUE MAR 29 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1032 PM     HAIL             3 NNW MELBORNE          33.61N 88.21W
03/29/2011  E1.00 INCH       LAMAR              AL   EMERGENCY MNGR

&&

LINHARES

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1042 PM CDT TUE MAR 29 2011

ALZ030-031-300430-
GREENE AL-SUMTER AL-
1042 PM CDT TUE MAR 29 2011

...SIGNIFICANT WEATHER ADVISORY FOR GREENE AND SUMTER COUNTIES UNTIL
1130 PM CDT...

AT 1043 PM CDT...THE NATIONAL WEATHER SERVICE WAS TRACKING A STRONG
THUNDERSTORM NEAR LIVINGSTON...MOVING NORTHEAST AT 40 MPH.

PEA SIZE HAIL IS EXPECTED WITH THIS STORM...ALONG WITH FREQUENT
DANGEROUS LIGHTNING.

LOCATIONS IN OR NEAR THE PATH OF THIS STORM INCLUDE...
  EUTAW...
  BLUFFPORT...
  EPES...
  GAINESVILLE...
  TISHABEE...

&&

LAT...LON 3283 8835 3313 8786 3310 8783 3303 8783
      3303 8774 3300 8771 3298 8775 3294 8774
      3291 8777 3289 8782 3285 8783 3280 8782
      3277 8787 3276 8781 3272 8783 3270 8779
      3236 8840
TIME...MOT...LOC 0343Z 241DEG 34KT 3265 8819

75

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1048 PM CDT TUE MAR 29 2011

ALZ013-015-023-300430-
FAYETTE AL-TUSCALOOSA AL-WALKER AL-
1048 PM CDT TUE MAR 29 2011

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN WALKER...SOUTHEASTERN
FAYETTE AND NORTHERN TUSCALOOSA COUNTIES UNTIL 1130 PM CDT...

AT 1048 PM CDT...THE NATIONAL WEATHER SERVICE WAS TRACKING A STRONG
THUNDERSTORM 7 MILES NORTH OF SAMANTHA...OR 16 MILES SOUTHEAST OF
FAYETTE...MOVING NORTHEAST AT 35 MPH.

PEA SIZE HAIL IS EXPECTED WITH THIS STORM...ALONG WITH FREQUENT
DANGEROUS LIGHTNING.

LOCATIONS IN OR NEAR THE PATH OF THIS STORM INCLUDE...
  BOLEY SPRINGS...
  OAKMAN...
  GORGAS...
  PARRISH...
  WINDHAM SPRINGS...

&&

LAT...LON 3378 8729 3360 8719 3357 8720 3356 8719
      3341 8768 3357 8776
TIME...MOT...LOC 0348Z 246DEG 29KT 3353 8762

75

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1049 PM CDT TUE MAR 29 2011

ALZ012-022-300430-
LAMAR AL-PICKENS AL-
1049 PM CDT TUE MAR 29 2011

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN LAMAR AND NORTHERN
PICKENS COUNTIES UNTIL 1130 PM CDT...

AT 1050 PM CDT...THE NATIONAL WEATHER SERVICE WAS TRACKING A STRONG
THUNDERSTORM NEAR ETHELSVILLE...OR 11 MILES EAST OF COLUMBUS...MOVING
NORTHEAST AT 30 MPH.

PEA SIZE HAIL IS EXPECTED WITH THIS STORM...ALONG WITH FREQUENT
DANGEROUS LIGHTNING.

LOCATIONS IN OR NEAR THE PATH OF THIS STORM INCLUDE...
  MILLPORT...
  KENNEDY...
  ASHCRAFT CORNER...
  SHAW...

&&

LAT...LON 3343 8829 3353 8828 3368 8795 3353 8794
      3353 8784 3348 8784 3334 8825 3343 8830
TIME...MOT...LOC 0350Z 245DEG 28KT 3347 8819

75

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1052 PM CDT TUE MAR 29 2011

ALZ011-300430-
MARION AL-
1052 PM CDT TUE MAR 29 2011

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN MARION COUNTY UNTIL 1130
PM CDT...

AT 1052 PM CDT...THE NATIONAL WEATHER SERVICE WAS TRACKING A STRONG
THUNDERSTORM NEAR TREMONT...OR 13 MILES NORTHWEST OF HAMILTON...
MOVING NORTHEAST AT 45 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER IS EXPECTED WITH THIS STORM...
ALONG WITH FREQUENT DANGEROUS LIGHTNING.

LOCATIONS IN OR NEAR THE PATH OF THIS STORM INCLUDE...
  HAMILTON...
  WESTON...
  BRINN...
  HACKLEBURG...
  LAKE BUTTAHATCHEE...

THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND
TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS... FOR ADDITIONAL
INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.

&&

LAT...LON 3433 8808 3432 8764 3422 8763 3412 8765
      3407 8821 3432 8817 3433 8816 3433 8809
TIME...MOT...LOC 0352Z 246DEG 38KT 3423 8816

75