Alert archive / Alabama / Special Weather Statements in 2012

Special Weather Statement, NWS Birmingham, AL

August 17, 2012Cherokee County, Alabama

NWS Birmingham, AL issued this special weather statement at Aug 17, 2012, 1:59 AM CDT for Cherokee County, Alabama. It was in force for 46 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: Aug 17, 2012, 1:59 AM CDT (06:59 UTC)
Expired: Aug 17, 2012, 2:45 AM CDT
In force: 46 min
Issued by: NWS Birmingham, AL

County Cherokee County, AL

The radar

The Northeast Alabama radar (KHTX), 77 km from the middle of the area, began a volume at 07:00 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Birmingham, AL (KBMX), launched 00:00Z, 7.0 hours before the alert went out and 153 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: 1257 J/kg
Mixed-layer CIN: -32 J/kg
Mixed-layer LCL: 1382 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: -11 m²/s²
0-3 km storm-relative helicity: 60 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 Aug 17, 1:14 AM CDT, 45 minutes earlier.

Area forecast discussion, Aug 17, 1:14 AM CDT, 45 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
114 AM CDT FRI AUG 17 2012

.UPDATE...

MESOSCALE UPDATE.

&&

.DISCUSSION...

RATHER EXTENSIVE LINE OF THUNDERSTORMS HAVE PUSHED THROUGH TENNESSEE
AND WAS APPROACHING THE ALABAMA STATE LINE. THIS ACTIVITY WAS
LOCATED FROM NEAR CHATTANOOGA TO NEAR MEMPHIS. THESE STORMS HAVE A
HISTORY OF PRODUCING WINDS AROUND 60 MPH AND SOME QUARTER SIZE HAIL.

THE LATEST RUC ANALYSIS HAS PRECIPITABLE WATER VALUES MUCH LOWER
OVER NORTHERN ALABAMA...WITH HIGHER VALUES BACK TO THE NORTHWEST
NEAR THE FRONT OVER MISSOURI. MOISTURE TRANSPORT WOULD INDICATE SOME
NEW DEVELOPMENT IN NORTHWESTERN MISSISSIPPI AHEAD OF AN APPROACHING
SHORT WAVE TROUGH. THIS ACTIVITY WOULD HAVE A WESTERLY COMPONENT AND
MOVE INTO NORTH CENTRAL ALABAMA WITH THE LINE AROUND 3 AM. SURFACE
BASED CIN HAS INCREASED TO 150 WITH OVERALL BULK SHEAR VALUES
NEGLIGIBLE. LAPSE RATES ALSO ARE NOT OVERLY IMPRESSIVE AROUND 6.

EXPECT THAT FAR NORTH AREAS WILL EXPERIENCE THUNDERSTORMS
OVERNIGHT...STARTING BY 3 AM. THIS ACTIVITY MAY MAKE IT AS FAR SOUTH
AS INTERSTATE 59/20 BY DAYBREAK. AS FAR AS SEVERE STORMS GO...I
WOULD THINK THESE STORMS WOULD GRADUALLY LOSE SOME INTENSITY AS THEY
ENTER CENTRAL ALABAMA. THEREFORE...CAN NOT RULE OUT A STRAY SEVERE
STORM...A LARGE MAJORITY OF THE ACTIVITY WILL REMAIN BELOW SEVERE
LIMITS. BUT THE STORMS WILL BE CAPABLE OF PRODUCING SOME GUSTY
WINDS...FREQUENT LIGHTNING..AND HEAVY RAINFALL.

WILL MONITOR THE RADAR TRENDS CLOSELY THE NEXT FEW HOURS AND THE
DEVELOPMENT EXPECT IN NORTHERN MISSISSIPPI. THE MORNING DISCUSSION
WILL TALK MORE ABOUT SEVERE POTENTIAL TODAY.

75

&&

.AVIATION...

06Z TAF DISCUSSION.

WATCHING A LINE OF CONVECTION APPROACHING NORTHERN ALABAMA THIS
EVENING. THIS SQUALL LINE IS OUT AHEAD OF THE COLD FRONT THAT WILL
APPROACH THE AREA TOMORROW AFTERNOON. NOT EXPECTING THAT SPECIFIC
LINE OF STORMS TO AFFECT THE AREA OVERNIGHT...BUT SOME OF THE HIGH
RESOLUTION MODELS DO SHOW A PART OF THIS COMPLEX REDEVELOPING OVER
NORTHERN MISSISSIPPI AND MOVING INTO WEST CENTRAL ALABAMA BETWEEN
12Z AND 15Z. BASED ON THE CURRENT TRENDS AND MODEL DATA...WILL
BUMP UP THE ARRIVAL OF THUNDERSTORMS SLIGHTLY FROM THE PREVIOUS
FORECAST AND REPLACE THE VC WITH PREVAILING TSRA. WHILE CONVECTION
WILL NOT BE CONTINUOUS THROUGHOUT THE DAY...SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE AT ANY TIME THROUGH AT LEAST LATE
AFTERNOON OR EARLY EVENING.

FG/BR POTENTIAL OVERNIGHT...BELIEVE THE BOUNDARY LAYER WINDS WILL
BE UP JUST ENOUGH TO PREVENT ANY PROLONGED PERIOD OF LOWER
VISIBILITY FOR THE NORTHERN TAF SITES. IF THEY DROP IT IS MORE
LIKELY TO HAPPEN EARLY. FOR MGM AND TOI...WINDS ARE A LITTLE BIT
LESS AND THESE SITES ARE FAR REMOVED FROM THE CONVECTIVE TRENDS
OVER NORTHERN ALABAMA. THE BETTER POTENTIAL FOR LOWER VIS WILL BE
IN THE SOUTH.

&&

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

&&

08/88

Hazardous weather outlook, Aug 16, 6:36 PM CDT, 7 hours 23 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BIRMINGHAM AL
636 PM CDT THU AUG 16 2012

ALZ011>015-017>050-172345-
MARION-LAMAR-FAYETTE-WINSTON-WALKER-BLOUNT-ETOWAH-CALHOUN-CHEROKEE-
CLEBURNE-PICKENS-TUSCALOOSA-JEFFERSON-SHELBY-ST. CLAIR-TALLADEGA-
CLAY-RANDOLPH-SUMTER-GREENE-HALE-PERRY-BIBB-CHILTON-COOSA-TALLAPOOSA-
CHAMBERS-MARENGO-DALLAS-AUTAUGA-LOWNDES-ELMORE-MONTGOMERY-MACON-
BULLOCK-LEE-RUSSELL-PIKE-BARBOUR-
636 PM CDT THU AUG 16 2012

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

.DAY ONE...TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

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

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT IS NOT
EXPECTED AT THIS TIME.

In the hours before

Special weather statement, Aug 17, 1:59 AM CDT, 0 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
159 AM CDT FRI AUG 17 2012

ALZ018-020-170745-
CHEROKEE AL-ETOWAH AL-
159 AM CDT FRI AUG 17 2012

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN ETOWAH AND CHEROKEE
COUNTIES UNTIL 245 AM CDT...

AT 157 AM CDT...THE NATIONAL WEATHER SERVICE WAS TRACKING A STRONG
OUTFLOW BOUNDARY FROM THUNDERSTORMS IN THE TENNESSEE VALLEY. WINDS
MAY BE ASSOCIATED WITH THIS OUTFLOW BOUNDARY WELL AHEAD OF THE
ACTUAL THUNDERSTORMS.

WIND GUSTS OF 30 TO 40 MPH ARE POSSIBLE.

LOCATIONS IN OR NEAR THE PATH OF THESE STORMS INCLUDE...
  LITTLE RIVER CANYON NATIONAL PRESERVE...
  CEDAR BLUFF...
  CENTRE MUNICIPAL AIRPORT...
  CENTRE...
  FORNEY...

&&

LAT...LON 3452 8550 3408 8542 3405 8547 3406 8620
      3415 8625 3419 8619 3419 8612 3421 8610
      3421 8585 3425 8584 3424 8582 3426 8580
      3426 8578 3438 8563 3443 8559 3449 8558
      3453 8551
TIME...MOT...LOC 0657Z 338DEG 24KT 3462 8534 3444 8566
          3445 8629

75

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 17, 2:03 AM CDT	Special Weather Statement	BMX	Marion	42 min
Aug 17, 2:39 AM CDT	Special Weather Statement	BMX	Winston	51 min
Aug 17, 2:42 AM CDT	Special Weather Statement	BMX	Marion	48 min
Aug 17, 3:18 AM CDT	Flash Flood Warning	BMX	Lamar	3 hr
Aug 17, 4:10 AM CDT	Special Weather Statement	BMX	Walker	50 min
Aug 17, 4:13 AM CDT	Special Weather Statement	BMX	Pickens	32 min
Aug 17, 4:33 AM CDT	Special Weather Statement	BMX	Pickens	42 min
Aug 17, 4:37 AM CDT	Special Weather Statement	BMX	Tuscaloosa	38 min
Aug 17, 5:54 AM CDT	Special Weather Statement	BMX	Sumter	51 min

Nearby

Special Weather Statements in Alabama, 2012 Every special weather statement in 2012

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; radar from the NEXRAD Level II archive.