Severe Thunderstorm Warning 103, NWS Birmingham, AL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
745 PM CDT THU APR 2 2009

.UPDATE...MESOSCALE DISCUSSION.

THE 0-6 KM SHEAR IS EXPECTED TO RAMP UP TO 80 TO 90 KNOTS ACROSS
NORTHERN HALF OF FORECAST AREA THROUGH 10 PM.  THIS SHOULD
MAINTAIN...IF NOT ENHANCE...THE TWO ONGOING CONVECTIVE BANDS.
SURFACE-BASED INSTABILITY IS EXPECTED TO WEAKEN WITH TIME...BUT
INCREASING SHEAR MAY COMPENSATE FOR LIMITED INSTABILITY.
STORM-RELATIVE HELICITY VALUES HAVE INCREASED OVER WESTERN ALABAMA
DURING THE PAST HOUR.  VALUES SHOULD REMAIN ABOVE 350 M2/S2 WITH
BOTH CONVECTIVE LINES.

03

&&

.AVIATION...00Z TAF DISCUSSION.

THUNDERSTORMS COULD STILL AFFECT THE NORTHERN TAF SITES WHICH
INCLUDES BHM...ANB...TCL AND EET. TEMPOS AND VCTS HAVE BEEN
INCLUDED TO REFLECT THE TIMING ON THESE STORMS. THERE IS STILL THE
POSSIBILITY THAT SOME OF THESE STORMS COULD BECOME SEVERE. THE
THREAT OF STORMS SHOULD END BETWEEN 05Z AND 06Z. AVIATION PROBLEMS
ARE STILL EXPECTED TO CONTINUE THOUGH. LOW CEILINGS ARE EXPECTED
PRETTY MUCH AREA WIDE. THERE COULD BE A FEW BREAKS IN THE CLOUDS
FROM TIME TO TIME...BUT FOR THE MOST PART EXPECT CLOUDY
CONDITIONS. ALSO...AS THE COLD FRONT MOVES THROUGH...WINDS ARE
EXPECTED TO BECOME QUITE STRONG AND GUSTY. SKIES ARE EXPECTED TO
CLEAR BY 18Z TOMORROW.

10/ARM

&&

.PREV DISCUSSION... /ISSUED 540 PM CDT THU APR 2 2009/

UPDATE...MESOSCALE DISCUSSION...

THROUGH 9 PM...SURFACE-BASED CAPES OVER NORTH-CENTRAL ALABAMA...ON
THE ORDER OF 500 J/KG...TIED WITH ONGOING CONVECTION...DO NOT
TRANSLATE NORTHEAST.  IN OTHER WORDS...THESE STORMS COULD BECOME
SLIGHTLY ELEVATED AS THEY MOVE EAST OVER ETOWAH...CALHOUN...AND
TALLADEGA COUNTIES...AND POINTS EASTWARD.  HOWEVER...THIS AREA IS
EXPECTED TO BE THE HOT SPOT FOR STORM-RELATIVE HELICITIES...WITH
VALUES ABOVE 400 M2/S2 THROUGH 9 PM.  THEREFORE...EXPECT ROTATING
STORMS OVER OUR NORTHEAST COUNTIES...BUT NOT SURE IF THE ROTATION
WILL REACH THE GROUND OR NOT.

REGARDING NEW DEVELOPMENT INTO NORTHWEST ALABAMA...THE STORMS OVER
NORTHEAST MISSISSIPPI SHOULD BE ELEVATED AS THEY MOVE INTO NORTHWEST
ALABAMA THROUGH 7 PM.  HOWEVER...THE RUC MODEL DOES INDICATE
INCREASING INSTABILITY BETWEEN 7 AND 9 PM...RIGHT AHEAD OF
APPROACHING COLD FRONT.  BEST STORM-RELATIVE HELICITIES LAG BEHIND
THE COLD FRONT WITH TIME.

03

DISCUSSION...

A PRE-FRONTAL LINE OF SHOWERS AND THUNDERSTORMS CURRENTLY MOVING
INTO WEST CENTRAL ALABAMA WILL CONTINUE EASTWARD ACROSS THE STATE.
THIS LINE WILL ENCOUNTER A MORE STABLE AIRMASS LEFT OVER FROM THIS
MORNINGS RAIN AND LOW CLOUDS ACROSS EAST CENTRAL ALABAMA. AS A
WARM FRONT CONTINUES TO LIFT NORTH AHEAD OF THIS LINE...SOME
DESTABILIZATION IS EXPECTED...CONTINUING A STRONG TO SEVERE THREAT
ALONG THE LINE.

UPPER LEVEL TROUGH REMAINS BACK ACROSS ARKANSAS THIS AFTERNOON...AND
IS EXPECTED TO MOVE ACROSS THE TENNESSEE RIVER VALLEY AND INTO THE
OHIO RIVER VALLEY BY TOMORROW MORNING. ALONG THE ASSOCIATED COLD
FRONT...THUNDERSTORM DEVELOPMENT IS OCCURRING ALONG A LINE
STRETCHING FROM CENTRAL ARKANSAS SOUTHWARD INTO NORTHEAST
LOUISIANA..I.AND MOVING TO THE NORTHEAST. AS THIS SYSTEM
SHIFTS EASTWARD...EXPECTING THE AIRMASS OVER CENTRAL ALABAMA TO
DESTABILIZE BEHIND THE CURRENT LINE OF STORMS...AND WILL HAVE TO
MONITOR FOR ANY DEVELOPMENT ALONG THE FRONT. IF THERE IS
REDEVELOPMENT...ALL MODES OF SEVERE WEATHER WILL BE POSSIBLE.
EXPECTED TIMING OF THE FRONT INTO WEST CENTRAL ALABAMA IS BETWEEN
8-10PM...9-11PM ALONG THE I-65 CORRIDOR...AND 10-MIDNIGHT IN EAST
CENTRAL ALABAMA.

BEHIND THIS SYSTEM...EXPECT DRIER AIR TO FILTER INTO THE REGION AS
UPPER LEVEL RIDGING BUILDS INTO THE SOUTHEASTERN CONUS. COOLER AIR
IN NORTHWESTERLY FLOW WILL ALLOW FOR SLIGHTLY COOLER TEMPS ON
FRIDAY...WITH HIGHS IN THE MID 60S. AS THE SURFACE HIGH SHIFTS
EASTWARD SATURDAY...AND SOUTHERLY FLOW DEVELOPS...HIGHS WILL RETURN
TO THE MID 70S.

A STORM SYSTEM MOVING INTO THE NORTHERN PLAINS SATURDAY WILL DRAG A
FRONT THROUGH CENTRAL ALABAMA ON SUNDAY. AS THIS SYSTEM CROSSES THE
AREA...THERE LOOKS TO BE A CHANCE OF STRONG TO SEVERE THUNDERSTORMS
SUNDAY AFTERNOON AND EVENING. HIGH PRESSURE WILL BUILD INTO THE
REGION BEHIND THIS SYSTEM...KEEPING CONDITIONS DRY THROUGH THE
MIDDLE OF THE WEEK. THERE WILL BE A GREATER COLD AIR PUSH BEHIND
THIS FRONT...AND TEMPERATURES FOR THE BEGINNING OF NEXT WEEK WILL BE
ABOUT 10-15 DEGREES BELOW NORMAL...WITH HIGHS IN THE MID TO UPPER
50S.

SOUTHERLY FLOW RETURNS WEDNESDAY AS THE NEXT STORM SYSTEM MOVES INTO
THE PLAINS...WHICH WILL BRING A FRONT...AND THE CHANCE OF SHOWERS
AND THUNDERSTORMS...TO THE AREA NEXT THURSDAY.

14

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FOR ALL ZONES THROUGH 7 AM FRIDAY.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BIRMINGHAM AL
638 PM CDT THU APR 2 2009

ALZ011>015-017>050-031200-
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-
638 PM CDT THU APR 2 2009

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

.DAY ONE...TONIGHT.

A FEW TORNADOES ARE STILL POSSIBLE...AS NEW THUNDERSTORMS DEVELOP
AHEAD OF AN APPROACHING COLD FRONT.  STRONG TO SEVERE THUNDERSTORMS
ARE EXPECTED WEST OF INTERSTATE 65 UNTIL MIDNIGHT...AND EAST OF
INTERSTATE 65 BETWEEN 11 PM AND 2 AM.

STRONG...GUSTY WINDS...UP TO 40 MPH...ARE POSSIBLE ALONG AND BEHIND
THE COLD FRONT OVERNIGHT.

RIVER FLOODING CONTINUES FOR SEVERAL COUNTIES IN SOUTHWEST ALABAMA.
PLEASE REFER TO RIVER FLOOD STATEMENTS FOR ADDITIONAL DETAILS
REGARDING YOUR AREA.

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

RIVERS WILL REMAIN IN FLOOD THROUGH AT LEAST FRIDAY EVENING FOR
SEVERAL COUNTIES IN SOUTHWEST ALABAMA. PLEASE REFER TO RIVER FLOOD
STATEMENTS FOR ADDITIONAL DETAILS REGARDING YOUR AREA.

SEVERE THUNDERSTORMS ARE POSSIBLE ON SUNDAY AFTERNOON...LASTING
INTO THE OVERNIGHT HOURS.

.SPOTTER INFORMATION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT WILL LIKELY
BE NECESSARY ON TODAY.

03

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
803 PM CDT THU APR 02 2009

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

0744 PM     TSTM WND DMG     DETROIT                 34.03N 88.17W
04/02/2009                   LAMAR              AL   EMERGENCY MNGR

            HALF OF A HOUSE DESTROYED ON DETROIT ROAD IN DETROIT.

&&

10.5

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE BIRMINGHAM AL
804 PM CDT THU APR 02 2009

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

0747 PM     TSTM WND DMG     SULLIGENT               33.89N 88.13W
04/02/2009                   LAMAR              AL   EMERGENCY MNGR

            NUMEROUS TREES AND SIGNS WERE BLOWN DOWN NEAR SULLIGENT.

&&

10.5

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