Severe Thunderstorm Warning 82, NWS Birmingham, AL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
633 PM CDT SUN MAY 2 2010

.UPDATE...AVIATION DISCUSSION.

&&

.DISCUSSION...

COMPLICATED WEATHER SCENARIO AS CENTRAL ALABAMA REMAINS TRAPPED
BETWEEN DEEP TROUGH TO OUR WEST AND EXPANSIVE RIDGE CENTERED NEAR
SOUTHERN FLORIDA AND CUBA. THIS PATTERN IS KEEPING DEEP SOUTHERLY
FLOW AT THE SURFACE TO MID LEVELS WITH SOUTHWESTERLY FLOW ALOFT. A
VERY SLOW MOVING FRONTAL BOUNDARY IS POSITIONED FROM WESTERN
TENNESSEE SOUTHWARD INTO EASTERN LOUISIANA.

MODELS HAVE BEEN TRYING FOR SEVERAL RUNS TO PUSH THIS SYSTEM
THROUGH ALABAMA BUT THE RIDGING TO OUR SOUTHEAST SEEMS TO HAVE
BEEN TOO STRONG FOR ANY SIGNIFICANT PUSH EASTWARD. WATER VAPOR
IMAGERY SHOWED AN UPPER LEVEL IMPULSE LIFTING THROUGH THE BASE OF
THE TROUGH TODAY AND MIGHT HAVE NUDGED THINGS A TAD IN OUR
DIRECTION...THUS THE DEVELOPMENT OF SHOWERS AND STORMS FOR AREAS
WEST OF INTERSTATE 65. HOWEVER...SINCE THE FRONT STILL REMAINS
WELL BACK TO THE WEST...THE MAIN FLOODING THREAT WILL BEGIN
TONIGHT FOR MOST OF THE AREA AND LINGER THROUGH TOMORROW FOR
SOUTHEAST ALABAMA. THIS FRONT IS EXPECTED TO GET A PUSH INTO THE
STATE LATER TONIGHT AND TOMORROW AS AN UPPER TROUGH OVER THE
NORTHERN PLAINS PHASES WITH THE SOUTHERN STREAM TROUGH AND
FLATTENS OUT THE RIDGE. THAT IS IF YOU BUY INTO THE CURRENT MODEL
TRENDS.

IN OUR FAVOR TONIGHT...THERE DOES NOT APPEAR TO BE ANY SIGNIFICANT
SHORT WAVE FORCING ALOFT TO INTERACT WITH THE 2+ INCH PW
WATER TOTALS THAT ARE CURRENTLY IN PLACE. ADDITIONALLY...SOME
CAPPING EVIDENT IN 18Z SOUNDING SHOULD LIMIT WIDESPREAD SEVERE
THREAT.

SO...IF THE RIDGING DOES WEAKEN AND THE FRONT IS ALLOWED TO SLIDE ON
THROUGH...THEN RAINFALL AMOUNTS COULD BE SEVERAL INCHES LESS THAN
ORIGINALLY THOUGHT YESTERDAY. THIS WILL BE THE GENERAL PHILOSOPHY OF
THE FORECAST WITH HEAVY RAIN AND FLOODING STILL A CONCERN BUT
SOMEWHAT LESSER AMOUNTS LIKELY.

FORECAST TIMING WILL BASED OFF THE 12Z EURO WHICH HAS HAD A SLOWER
AND MORE REALISTIC SOLUTION THUS FAR. THE FRONTAL BOUNDARY SHOULD
SAG INTO THE SOUTHERN QUARTER OF THE STATE BY TUESDAY MORNING AND
STALL UNTIL A FINAL KICKER WAVE MOVES THROUGH TUESDAY AFTERNOON. DRY
WEATHER FOR THE ENTIRE AREA FROM TUESDAY NIGHT THROUGH FRIDAY.
ANOTHER FRONTAL SYSTEM MOVES THROUGH THIS WEEKEND BRINGING A CHANCE
FOR SHOWERS OR A THUNDERSTORM. TEMPERATURES ARE EXPECTED TO BE ABOVE
NORMAL NEXT WEEK.

&&

.AVIATION...00Z TAF DISCUSSION.

MAIN CHALLENGE WITH THE AVIATION FORECAST IS TRYING TO TIME THE
ARRIVAL AND DEPARTURE OF SHOWERS AND THUNDERSTORMS.  THE RAIN IS
CONFINED TO A FAIRLY NARROW BAND...WHICH IS MOVING RATHER SLOWLY
EASTWARD. THUS...WHEN THE RAIN GETS TO A PARTICULAR AREA IT WILL
STICK AROUND FOR A WHILE. MOST OF THE RAIN IS LIGHT TO MODERATE
INTENSITY...BUT THERE ARE EMBEDDED STRONG THUNDERSTORMS THAT BRING A
SIGNIFICANT REDUCTION TO VISIBILITY WHEN THEY MOVE THROUGH. I DID MY
BEST ON THE TIMING...GIVEN RECENT RADAR TRENDS AND COMPUTER MODEL
OUTPUT...BUT I SUSPECT THERE WILL NEED TO BE A FEW ADJUSTMENTS AS
THE NIGHT WEARS ON.

INDICATIONS ARE THAT THE PRECIPITATION SHOULD MAKE SLOW BUT STEADY
PROGRESS EASTWARD THROUGH THE 24 HOUR FORECAST PERIOD. I HAVE ABOUT
AVERAGE CONFIDENCE IN THE NOTION THAT CONDITIONS SHOULD IMPROVE TO
VFR FOR MOST SPOTS BY 03/1800Z.

NOTICE...KEET TAF WILL HAVE (AMD LTD TO VIS WIND AND WX) AMENDED
TO THE END OF THE FORECAST UNTIL FURTHER NOTICE WHILE CEILOMETER
DATA IS BEING MONITORED FOR ACCURACY.

/61/

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 1 AM CDT MONDAY FOR THE FOLLOWING COUNTIES:
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.

FLASH FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH MONDAY
EVENING FOR THE FOLLOWING COUNTIES: AUTAUGA...BIBB...BLOUNT...
CALHOUN...CHEROKEE...CHILTON...CLAY...CLEBURNE...COOSA...
DALLAS...ELMORE...ETOWAH...HALE...JEFFERSON...LOWNDES...
MARENGO...MONTGOMERY...PERRY...RANDOLPH...SHELBY...ST. CLAIR...
TALLADEGA...TALLAPOOSA.

FLASH FLOOD WATCH THROUGH MONDAY MORNING FOR THE FOLLOWING
COUNTIES: FAYETTE...GREENE...LAMAR...MARION...PICKENS...SUMTER...
TUSCALOOSA...WALKER...WINSTON.

FLASH FLOOD WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING FOR
THE FOLLOWING COUNTIES: BARBOUR...BULLOCK...CHAMBERS...LEE...
MACON...PIKE...RUSSELL.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BIRMINGHAM AL
245 PM CDT SUN MAY 2 2010

ALZ011>015-017>050-031130-
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-
245 PM CDT SUN MAY 2 2010

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

AN APPROACHING SYSTEM WILL BRING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS TO CENTRAL ALABAMA THIS AFTERNOON AND TONIGHT. STRONG
DAMAGING WINDS AND HAIL WILL BE POSSIBLE. AN ISOLATED TORNADO CAN
NOT BE RULED OUT BUT THE THREAT WILL DECREASE AFTER SUNSET. THE MAIN
THUNDERSTORM THREAT AREA WILL GENERALLY BE ALONG AND WEST OF A
LINE FROM MONTGOMERY TO WEDOWEE. THE STORMS WILL GENERALLY BE
CONFINED TO AREAS WEST OF INTERSTATE 65 THROUGH 4 PM...THEN
SLOWLY PROGRESS EASTWARD UNTIL 10 PM OR MIDNIGHT. FLASH FLOODING WILL
ALSO BE A POSSIBILITY AS MOISTURE LEVELS REMAIN VERY HIGH. 1 TO 3
INCHES OF RAIN...WITH ISOLATED HIGHER TOTALS...REMAIN POSSIBLE THIS
AFTERNOON AND TONIGHT FOR ALL AREAS EXCEPT FAR SOUTHEAST.

A TIGHTENING SURFACE PRESSURE GRADIENT WILL CAUSE SUSTAINED WINDS OF
AROUND 15 MPH WITH A FEW GUSTS AROUND 40 MPH THROUGH THIS EVENING. A
FEW WEAKER TREES OR LIMBS MAY FALL.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

SEVERE WEATHER WILL AGAIN BE POSSIBLE ON MONDAY AS THIS SLOW MOVING
SYSTEM ENTERS CENTRAL ALABAMA. THE MAIN THREAT WILL BE DAMAGING
WINDS AND THE THREAT WILL BE CONFINED TO AREAS ALONG AND SOUTH OF
INTERSTATE 85.

THE COLD FRONT ASSOCIATED WITH THIS SYSTEM IS EXPECTED TO BECOME
STATIONARY ACROSS THE SOUTHERN HALF OF THE AREA BY TUESDAY.
FLASH FLOODING AND RIVER FLOODING WILL BE POSSIBLE THROUGH TUESDAY.
RAINFALL TOTALS THROUGH TUESDAY EVENING OF 2 TO 4 INCHES...WITH
LOCALLY HIGHER AMOUNTS...WILL BE POSSIBLE AREA WIDE.

.SPOTTER INFORMATION STATEMENT...

LOCAL ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT WILL
LIKELY BE NEEDED THROUGH MONDAY.

75

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
242 PM CDT SUN MAY 2 2010

ALZ015-023-024-022015-
JEFFERSON-TUSCALOOSA-WALKER-
242 PM CDT SUN MAY 2 2010

...SIGNIFICANT WEATHER ALERT FOR JEFFERSON...TUSCALOOSA AND WALKER
COUNTIES UNTIL 315 PM CDT...

AT 236 PM CDT...THE NATIONAL WEATHER SERVICE IS TRACKING A STRONG
THUNDERSTORM NEAR MCFARLAND MALL...OR 9 MILES SOUTH OF TUSCALOOSA...
MOVING NORTHEAST AT 60 MPH.

WINDS UP TO 50 MPH AND HEAVY DOWNPOURS ARE EXPECTED WITH THIS STORM.

* LOCATIONS IN OR NEAR THE PATH INCLUDE...
  COTTONDALE.
  FLEETWOOD.
  BROOKWOOD.
  ABERNANT.
  BULL CITY.
  LITTLE SHOAL.

STAY TUNED TO NOAA WEATHER RADIO...COMMERCIAL RADIO...OR YOUR LOCAL
TELEVISION STATIONS FOR LATER STATEMENTS AND POSSIBLE WARNINGS
CONCERNING THIS WEATHER SITUATION.

12/SIRMON

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
500 PM CDT SUN MAY 2 2010

ALZ011-022245-
MARION-
500 PM CDT SUN MAY 2 2010

...SIGNIFICANT WEATHER ALERT FOR MARION COUNTY UNTIL 545 PM CDT...

AT 457 PM CDT...THE NATIONAL WEATHER SERVICE IS TRACKING STRONG
THUNDERSTORMS ALONG A LINE EXTENDING FROM FAIRVIEW TO NEW SALEM...OR
ALONG A LINE EXTENDING FROM 9 MILES SOUTHWEST OF RED BAY TO 12 MILES
SOUTHEAST OF FULTON...MOVING NORTHEAST AT 60 MPH.

PEA SIZE HAIL...WINDS UP TO 40 MPH...AND FREQUENT CLOUD TO GROUND
LIGHTNING ARE EXPECTED WITH THESE STORMS.

* LOCATIONS IN OR NEAR THE PATH INCLUDE...
  BYRD.
  WESTON.
  PEA RIDGE.
  PINEY GROVE.
  TESSNER.
  BEAR CREEK.

THE GUSTY WINDS WILL BE CAPABLE OF KNOCKING DOWN SMALL TREES...TREE
LIMBS...AND POWERLINES. SEEK SAFE SHELTER UNTIL THE STORM HAS PASSED.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 700 PM CDT SUNDAY
EVENING FOR NORTHWESTERN ALABAMA.

STAY TUNED TO NOAA WEATHER RADIO...COMMERCIAL RADIO...OR YOUR LOCAL
TELEVISION STATIONS FOR LATER STATEMENTS AND POSSIBLE WARNINGS
CONCERNING THIS WEATHER SITUATION.

17/KLAWS

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
638 PM CDT SUN MAY 2 2010

ALZ011-012-030015-
LAMAR-MARION-
638 PM CDT SUN MAY 2 2010

...SIGNIFICANT WEATHER ALERT FOR LAMAR AND MARION COUNTIES UNTIL 715
PM CDT...

AT 635 PM CDT...THE NATIONAL WEATHER SERVICE IS TRACKING A STRONG
THUNDERSTORM 7 MILES WEST OF SULLIGENT...MOVING NORTHEAST AT 65 MPH.

PEA SIZE HAIL...WINDS UP TO 40 MPH...AND FREQUENT CLOUD TO GROUND
LIGHTNING ARE EXPECTED WITH THIS STORM.

* LOCATIONS IN OR NEAR THE PATH INCLUDE...
  PINE SPRINGS.
  HENSON SPRINGS.
  PIKEVILLE.
  RANKIN FITE AIRPORT.
  BRINN.
  TESSNER.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 700 PM CDT SUNDAY
EVENING FOR NORTHWESTERN ALABAMA.

STAY TUNED TO NOAA WEATHER RADIO...COMMERCIAL RADIO...OR YOUR LOCAL
TELEVISION STATIONS FOR LATER STATEMENTS AND POSSIBLE WARNINGS
CONCERNING THIS WEATHER SITUATION.

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