Alert archive / Alabama / Tornado Watches in 2016

Tornado Watch 13

February 2, 201620 counties in Alabama

The Storm Prediction Center issued this tornado watch at Feb 2, 2016, 9:59 PM CST for 20 counties in Alabama. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Feb 2, 2016, 9:59 PM CST (03:59 UTC)
Expired: Feb 3, 2016, 4:00 AM CST
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 0.5 in
Strongest gust expected: 60 kt

Counties Autauga County, AL, Bibb County, AL, Chilton County, AL, Clay County, AL, Coosa County, AL, Dallas County, AL, Elmore County, AL, Greene County, AL, Hale County, AL, Jefferson County, AL, Lowndes County, AL, Marengo County, AL, Montgomery County, AL, Perry County, AL, Pickens County, AL, Shelby County, AL, Sumter County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL

The radar

The Birmingham radar (KBMX), 78 km from the middle of the area, began a volume at 03:59 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 40%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 5%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 60%

Warnings issued inside it

3 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Feb 2, 10:39 PM CST	Tornado Warning	BMX	Perry	13 min
Feb 2, 11:04 PM CST	Tornado Warning	BMX	Pickens	13 min
Feb 3, 2:56 AM CST	Flash Flood Warning	BMX	Dallas, Perry	6 hr

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Birmingham, AL (KBMX), launched 00:00Z, 4.0 hours before the alert went out and 77 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: 313 J/kg
Mixed-layer CIN: -40 J/kg
Mixed-layer LCL: 765 m above ground
0-6 km bulk shear: 58 kt
0-1 km storm-relative helicity: 371 m²/s²
0-3 km storm-relative helicity: 518 m²/s²
Significant tornado parameter: 0.9
Supercell composite: 5.2

Open this sounding in Storm Lab

The text

As transmitted.

435 
WWUS20 KWNS 030355
SEL3  
SPC WW 030355
ALZ000-031000-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 13
NWS STORM PREDICTION CENTER NORMAN OK
1000 PM CST TUE FEB 2 2016

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* TORNADO WATCH FOR PORTIONS OF 
  CENTRAL AND WEST CENTRAL ALABAMA

* EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 1000 PM
  UNTIL 400 AM CST.

* PRIMARY THREATS INCLUDE...
  A COUPLE TORNADOES POSSIBLE
  ISOLATED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

SUMMARY...BANDS OF THUNDERSTORMS WILL PERSIST OVERNIGHT ALONG AND
AHEAD OF A COLD FRONT MOVING EASTWARD FROM MISSISSIPPI TO ALABAMA. 
THE STORM ENVIRONMENT WILL REMAIN SUFFICIENT FOR THE RISK OF A
COUPLE OF TORNADOES...AS WELL AS A FEW DAMAGING GUSTS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 55 STATUTE
MILES EAST AND WEST OF A LINE FROM 30 MILES WEST OF BIRMINGHAM
ALABAMA TO 50 MILES SOUTH OF TUSCALOOSA ALABAMA.  FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

&&

OTHER WATCH INFORMATION...THIS TORNADO WATCH REPLACES TORNADO
WATCH NUMBER 11. WATCH NUMBER 11 WILL NOT BE IN EFFECT AFTER 1000
PM CST. CONTINUE...WW 12...

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
400. MEAN STORM MOTION VECTOR 24035.


...THOMPSON

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 2, 6:52 PM CST	Tornado Watch	SPC	Baldwin, Choctaw, Clarke, Mobile, Monroe, Washington and 1 more	8 hr
Feb 2, 8:50 PM CST	Mesoscale Discussion	SPC	Bibb, Blount, Chilton, Colbert, Cullman, Fayette and 22 more	55 min
Feb 2, 10:23 PM CST	Mesoscale Discussion	SPC	Baldwin, Choctaw, Clarke, Mobile, Monroe, Washington and 1 more	2 hr
Feb 3, 1:30 AM CST	Mesoscale Discussion	SPC	Calhoun, Clay, Coosa, Elmore, Macon, Talladega and 1 more	60 min

Nearby

Tornado Watches in Alabama, 2016 Every tornado watch in 2016

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.