Alert archive / Alabama / Tornado Watches in 2020

Tornado Watch 38

March 3, 202021 counties in Alabama

The Storm Prediction Center issued this tornado watch at Mar 3, 2020, 5:12 AM CST for 21 counties in Alabama. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Mar 3, 2020, 5:12 AM CST (11:12 UTC)
Expired
Mar 3, 2020, 10:08 AM CST
In force
5 hr
Issued by
the Storm Prediction Center
Largest hail expected
1 in
Strongest gust expected
60 kt
All 21 counties

Autauga County, AL, Bibb County, AL, Bullock County, AL, Chambers County, AL, Chilton County, AL, Clay County, AL, Coosa County, AL, Dallas County, AL, Elmore County, AL, Greene County, AL, Hale County, AL, Lee County, AL, Lowndes County, AL, Macon County, AL, Marengo County, AL, Montgomery County, AL, Perry County, AL, Randolph County, AL, Russell County, AL, Sumter County, AL, Tallapoosa County, AL

The radar

The Birmingham radar (KBMX), 53 km from the middle of the area, began a volume at 11:12 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
50%
One or more gusts of 65 knots or more
20%
Ten or more severe hail reports
20%
One or more hailstones of 2 inches or more
10%
Six or more combined severe hail and wind reports
70%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Mar 3, 5:33 AM CSTSevere Thunderstorm WarningBMXHale42 min
Mar 3, 6:29 AM CSTTornado WarningBMXBibb, Chilton, Perry31 min
Mar 3, 6:43 AM CSTSevere Thunderstorm WarningBMXAutauga, Chilton, Dallas, Perry37 min

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, 11.2 hours before the alert went out and 53 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-pSkew-T log-p diagram, Birmingham, AL at 00:00Z on 2020-03-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 299 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Birmingham, AL at 00:00Z on 2020-03-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 250 square meters per square second.1939587897117136156Sfc1 km3 km6 km9 kmRMLM
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
299 J/kg
Mixed-layer CIN
-23 J/kg
Mixed-layer LCL
648 m above ground
0-6 km bulk shear
60 kt
0-1 km storm-relative helicity
250 m²/s²
0-3 km storm-relative helicity
250 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3

Open this sounding in Storm Lab

The text

As transmitted.

450 
WWUS20 KWNS 031109
SEL8  
SPC WW 031109
ALZ000-031700-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 38
NWS Storm Prediction Center Norman OK
510 AM CST Tue Mar 3 2020

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Parts of central Alabama

* Effective this Tuesday morning from 510 AM until 1100 AM CST.

* Primary threats include...
  A couple tornadoes possible
  Scattered damaging wind gusts to 70 mph possible
  Isolated large hail events to 1 inch in diameter possible

SUMMARY...A cluster of storms with embedded supercells and bowing
segments will move eastward across central Alabama through the
morning.  The threat for damaging gusts and a couple of tornadoes
will increase some as it warms and moistens at the surface through
the morning.

The tornado watch area is approximately along and 25 statute miles
north and south of a line from 155 miles west of Auburn AL to 15
miles northeast of Auburn AL. For a complete depiction of the watch
see the associated watch outline update (WOUS64 KWNS WOU8).

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.

&&

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 1 inch. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean
storm motion vector 27040.

...Thompson

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Mar 3, 2:34 AM CSTMesoscale DiscussionSPCLauderdale116 min
Mar 3, 2:52 AM CSTMesoscale DiscussionSPCColbert, Fayette, Franklin, Greene, Lamar, Marion and 2 more2 hr
Mar 3, 7:25 AM CSTMesoscale DiscussionSPCAutauga, Bibb, Bullock, Chambers, Chilton, Clay and 8 more2 hr
Mar 3, 9:16 AM CSTMesoscale DiscussionSPCBarbour, Bullock, Russell89 min
Mar 3, 12:52 PM CSTMesoscale DiscussionSPCAutauga, Barbour, Bullock, Chambers, Chilton, Dallas and 12 more2 hr

Nearby

Tornado Watches in Alabama, 2020Every tornado watch in 2020

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.