Alert archive / Alabama / Special Weather Statements in 2011

Special Weather Statement, NWS Birmingham, AL

April 20, 2011Marion County, Alabama

NWS Birmingham, AL issued this special weather statement at Apr 20, 2011, 7:10 PM CDT for Marion County, Alabama. It was in force for 50 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Apr 20, 2011, 7:10 PM CDT (00:10 UTC)
Expired: Apr 20, 2011, 8:00 PM CDT
In force: 50 min
Issued by: NWS Birmingham, AL

County Marion County, AL

The nearest sounding before it

Birmingham, AL (KBMX), launched 00:00Z, 0.2 hours before the alert went out and 145 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 1060 J/kg
Mixed-layer CIN: -143 J/kg
Mixed-layer LCL: 1220 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 128 m²/s²
0-3 km storm-relative helicity: 84 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Birmingham, AL wrote its last area forecast discussion before this special weather statement went out at Apr 20, 3:09 PM CDT, 4 hours 1 minute earlier.

Area forecast discussion, Apr 20, 3:09 PM CDT, 4 hours 1 minute before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
309 PM CDT WED APR 20 2011

.DISCUSSION...

COLD FRONT IS NOT EXPECTED TO SLIDE MUCH FARTHER SOUTH THAT WHERE
IT IS CURRENTLY LOCATED ALONG THE NORTHERN PORTIONS OF CENTRAL
ALABAMA. CONDITIONS SOUTH OF INTERSTATE 20 STILL REMAIN
FAVORABLE FOR SEVERE THUNDERSTORMS BUT THE EXTENSIVE CLOUD COVER
HAS KEPT MOST STORMS IN CHECK AS IT IS HELPING THE CAP HOLD IN
PLACE.

AS WE HEAD INTO THE OVERNIGHT HOURS...THE THREAT THEN SHIFTS TO
MORE OF A HEAVY RAIN EVENT. COMPUTER MODELS INDICATE THAT WE
COULD SEE SEVERAL UPPER LEVEL SHORT WAVES BETWEEN NOW AND TOMORROW
MORNING RIDING ALONG THE FRONTAL BOUNDARY. EACH WAVE COULD
ENHANCE CONVECTION WITH THE END RESULT BEING TRAINING
THUNDERSTORMS OR STORMS THAT KEEP MOVING ACROSS THE SAME LOCATION.
CURRENTLY THINKING THAT AMOUNTS WILL RANGE BETWEEN 1 AND 3
INCHES...WITH LOCALLY HIGHER AMOUNTS POSSIBLE. CURRENT THINKING IS
THAT BEST AREA FOR THE HEAVY RAIN WILL BE ALONG AND NORTH OF
INTERSTATE 20 AND WEST OF INTERSTATE 65.

FRONT IS EXPECTED TO PUSH BACK TO THE NORTH EARLY FRIDAY ENDING
THE HEAVY RAIN THREAT. DRY AND WARMER CONDITIONS ARE ON TAP JUST
IN TIME FOR THE WEEKEND.

HIGH PRESSURE CENTERED OVER THE ATLANTIC WILL PREVAIL FOR MUCH OF
NEXT WEEK...WHICH IS A PATTERN TYPICAL IN THE SUMMER. THIS WILL KEEP
TEMPERATURES ACROSS THE ENTIRE FORECAST AREA ABOVE NORMAL WHICH
WILL HELP TRIGGER ISOLATED AFTERNOON THUNDERSTORMS FOR MOST OF
NEXT WEEK.

10/ARM

&&

.AVIATION...18Z TAF DISCUSSION.

VERY COMPLEX AVIATION FORECAST UPCOMING AS MULTIPLE SHORTWAVES
ALOFT AND SURFACE BOUNDARIES INTERACT TODAY AND TONIGHT ACROSS
CENTRAL ALABAMA. THE FIRST WAVE OF SHOWERS AND THUNDERSTORMS HAS
STALLED NEAR THE I-20 TAF LOCATIONS BUT OUTFLOW HAS PUSHED
SOUTHWARD AND NEW THUNDERSTORM INITIATION HAS BEGUN BETWEEN MGM
AND TOI. BOTTOM LINE...THE NEXT 6 HOURS WILL BE DOMINATED BY THE
PRESENCE OF ONGOING CONVECTION. VC SHOWERS AND THUNDERSTORMS
SHOULD BE EXPECTED AT ANY TIME WITH PREDOMINANT SOUTHERLY WINDS
AND VARIABILITY IN ANY THUNDERSTORMS.

NONE OF THE 12Z MODELS HAVE A GOOD HANDLE ON THE CURRENT
WEATHER...BUT THE ATMOSPHERE SHOULD BECOME A LITTLE MORE STABLE
OVERNIGHT WITH MORE SCATTERED COVERAGE. SOUTHERLY WINDS ARE
EXPECTED TO CONTINUE IN THE LOWER TO MID LEVELS AND IFR CEILINGS
ARE EXPECTED OVERNIGHT AND BEGIN A SLOW LIFT LATE TOMORROW
MORNING.

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.

&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     57  79  58  83  57 /  70  60  50  20  10
ANNISTON    62  83  61  84  58 /  70  60  50  20  10
BIRMINGHAM  63  80  64  86  63 /  70  60  40  10  10
TUSCALOOSA  62  83  61  87  62 /  70  30  20  10  10
CALERA      64  81  62  85  60 /  70  40  30  10  10
AUBURN      64  85  63  84  61 /  50  40  40  10  10
MONTGOMERY  65  85  62  87  59 /  50  30  20  10  10
TROY        64  86  61  85  58 /  40  20  20  10  10

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH THURSDAY MORNING FOR THE FOLLOWING
COUNTIES: BIBB...BLOUNT...CALHOUN...CHEROKEE...CHILTON...CLAY...
CLEBURNE...COOSA...ETOWAH...FAYETTE...GREENE...HALE...
JEFFERSON...LAMAR...MARION...PERRY...PICKENS...RANDOLPH...
SHELBY...ST. CLAIR...SUMTER...TALLADEGA...TUSCALOOSA...WALKER...
WINSTON.

&&

Hazardous weather outlook, Apr 20, 6:14 PM CDT, 56 minutes before

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In the hours before

Special weather statement, Apr 20, 2:49 PM CDT, 4 hours 21 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
249 PM CDT WED APR 20 2011

ALZ012-022-202030-
LAMAR AL-PICKENS AL-
249 PM CDT WED APR 20 2011

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN LAMAR AND NORTHERN
PICKENS COUNTIES UNTIL 330 PM CDT...

AT 247 PM CDT...THE NATIONAL WEATHER SERVICE WAS TRACKING A STRONG
THUNDERSTORM 5 MILES SOUTH OF CALEDONIA...OR 6 MILES EAST OF COLUMBUS
AFB...MOVING EAST AT 30 MPH.

HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT
DANGEROUS LIGHTNING.

LOCATIONS IN OR NEAR THE PATH OF THIS STORM INCLUDE...
  VERNON...
  MILLPORT...
  REFORM...
  ETHELSVILLE...
  BEDFORD...

TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED
ROADWAY.

&&

LAT...LON 3381 8825 3382 8798 3369 8794 3353 8794
      3353 8790 3333 8785 3342 8829
TIME...MOT...LOC 1949Z 271DEG 28KT 3361 8834

14

Special weather statement, Apr 20, 7:10 PM CDT, 0 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
710 PM CDT WED APR 20 2011

ALZ011-012-210100-
LAMAR AL-MARION AL-
710 PM CDT WED APR 20 2011

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN MARION AND NORTHERN
LAMAR COUNTIES UNTIL 800 PM CDT...

AT 710 PM CDT...THE NATIONAL WEATHER SERVICE WAS TRACKING A STRONG
THUNDERSTORM NEAR DETROIT...OR 7 MILES NORTH OF SULLIGENT...MOVING
EAST AT 35 MPH.

PEA SIZE HAIL AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS
STORM.

LOCATIONS IN OR NEAR THE PATH OF THIS STORM INCLUDE...
  CREWS...
  BEAVERTON...
  GUIN...
  GU-WIN...
  BRILLIANT...

IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.

&&

LAT...LON 3407 8820 3423 8764 3406 8763 3398 8764
      3388 8821 3395 8823
TIME...MOT...LOC 0010Z 255DEG 30KT 3400 8812

75

The office that day

Everything else NWS Birmingham, AL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 20, 8:06 PM CDT	Severe Thunderstorm Warning	BMX	Lamar	39 min
Apr 20, 8:44 PM CDT	Severe Thunderstorm Warning	BMX	Lamar, Marion	46 min
Apr 20, 8:54 PM CDT	Flash Flood Warning	BMX	Lamar	3 hr
Apr 20, 9:08 PM CDT	Severe Thunderstorm Warning	BMX	Fayette, Lamar, Marion, Pickens, Winston	52 min
Apr 20, 9:36 PM CDT	Flash Flood Warning	BMX	Fayette, Lamar, Marion, Pickens, Winston	3 hr
Apr 20, 9:54 PM CDT	Severe Thunderstorm Warning	BMX	Fayette, Lamar, Marion, Pickens, Tuscaloosa, Walker and 1 more	66 min
Apr 20, 10:12 PM CDT	Flash Flood Warning	BMX	Fayette, Pickens, Tuscaloosa, Walker, Winston	3 hr
Apr 20, 10:13 PM CDT	Severe Thunderstorm Warning	BMX	Greene, Pickens, Sumter, Tuscaloosa	47 min
Apr 20, 10:36 PM CDT	Severe Thunderstorm Warning	BMX	Bibb, Blount, Jefferson, Tuscaloosa, Walker	54 min
Apr 20, 10:40 PM CDT	Areal Flood Advisory	BMX	Blount, Greene, Jefferson, Pickens, Sumter, Tuscaloosa and 1 more	3 hr
Apr 20, 11:26 PM CDT	Severe Thunderstorm Warning	BMX	Blount, Etowah, Jefferson, St. Clair, Talladega	49 min
Apr 20, 11:52 PM CDT	Areal Flood Advisory	BMX	Calhoun, Cherokee, Cleburne, Etowah, St. Clair, Talladega	3 hr
Apr 20, 11:58 PM CDT	Special Weather Statement	BMX	Calhoun, Cherokee, Cleburne, Etowah	62 min
Apr 21, 12:12 AM CDT	Special Weather Statement	BMX	Chambers, Clay, Coosa, Randolph	63 min
Apr 21, 12:30 AM CDT	Flash Flood Warning	BMX	Lamar, Marion, Pickens	3 hr
Apr 21, 12:40 AM CDT	Severe Thunderstorm Warning	BMX	Cleburne	28 min
Apr 21, 12:50 AM CDT	Special Weather Statement	BMX	Pickens	40 min
Apr 21, 3:03 AM CDT	Special Weather Statement	BMX	Greene, Sumter	42 min
Apr 21, 7:36 AM CDT	River Flood Warning	BMX	Greene, Hale, Marengo, Pickens, Sumter	65 hr
Apr 21, 8:08 AM CDT	Areal Flood Warning	BMX	Lamar	36 hr
Apr 21, 9:23 AM CDT	River Flood Warning	BMX	Greene, Hale, Marengo	5 days
Apr 21, 2:09 PM CDT	Severe Thunderstorm Warning	BMX	Sumter	36 min
Apr 21, 2:43 PM CDT	Special Weather Statement	BMX	Greene, Sumter	32 min
Apr 21, 3:24 PM CDT	Special Weather Statement	BMX	Greene	51 min
Apr 21, 6:13 PM CDT	Special Weather Statement	BMX	Chilton	47 min

Nearby

Special Weather Statements in Alabama, 2011 Every special weather statement in 2011

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.