Alert archive / Alabama / Tornado Watches in 2021
Tornado Watch 33
The Storm Prediction Center issued this tornado watch at Mar 17, 2021, 1:26 PM CDT for 13 counties in Alabama. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 17, 2021, 1:26 PM CDT (18:26 UTC)
- Expired
- Mar 17, 2021, 6:48 PM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 65 kt
Counties Calhoun County, AL, Chambers County, AL, Cherokee County, AL, Cleburne County, AL, Elmore County, AL, Etowah County, AL, Lee County, AL, Lowndes County, AL, Macon County, AL, Montgomery County, AL, Randolph County, AL, St. Clair County, AL, Tallapoosa County, AL
The radar
The Maxwell AFB radar (KMXX), 86 km from the middle of the area, began a volume at 18:27 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
- 70%
- One or more EF2 to EF5 tornadoes
- 60%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 70%
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 12:00Z, 6.4 hours before the alert went out and 95 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.
- Mixed-layer CAPE
- 658 J/kg
- Mixed-layer CIN
- -112 J/kg
- Mixed-layer LCL
- 759 m above ground
- 0-6 km bulk shear
- 59 kt
- 0-1 km storm-relative helicity
- 169 m²/s²
- 0-3 km storm-relative helicity
- 301 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.1
The text
As transmitted.
123
WWUS20 KWNS 171815
SEL3
SPC WW 171815
ALZ000-180000-
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 33
NWS Storm Prediction Center Norman OK
115 PM CDT Wed Mar 17 2021
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Central to eastern Alabama
* Effective this Wednesday afternoon and evening from 115 PM
until 700 PM CDT.
* Primary threats include...
A few tornadoes and a couple intense tornadoes likely
Scattered damaging winds and isolated significant gusts to 75
mph possible
Isolated very large hail events to 2 inches in diameter possible
SUMMARY...Discrete supercells across central Alabama may spread into
portions of eastern Alabama prior to early evening. All hazard types
are possible, with the greatest tornado threat expected in
east-central Alabama.
The tornado watch area is approximately along and 30 statute miles
east and west of a line from 30 miles east northeast of Gadsden AL
to 15 miles south southeast of Montgomery AL. 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...CONTINUE...WW 29...WW 30...WW 31...WW
32...
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2 inches. Extreme turbulence and surface wind
gusts to 65 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 25030.
...GramsSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 17, 10:56 AM CDT | Mesoscale Discussion | SPC | Autauga, Bibb, Chilton, Choctaw, Clarke, Coosa and 17 more | 2 hr |
| Mar 17, 11:36 AM CDT | Tornado Watch | SPC | Autauga, Bibb, Blount, Chilton, Choctaw, Clarke and 25 more | 7 hr |
| Mar 17, 12:02 PM CDT | Mesoscale Discussion | SPC | Choctaw, Clarke, Marengo | 58 min |
| Mar 17, 1:01 PM CDT | Mesoscale Discussion | SPC | Autauga, Chilton, Coosa, Elmore, Lowndes, Montgomery and 1 more | 89 min |
| Mar 17, 1:45 PM CDT | Mesoscale Discussion | SPC | Mobile | 90 min |
| Mar 17, 2:24 PM CDT | Mesoscale Discussion | SPC | Bibb, Chilton, Dallas, Hale, Marengo, Perry | 96 min |
| Mar 17, 5:49 PM CDT | Mesoscale Discussion | SPC | Autauga, Bibb, Blount, Bullock, Butler, Calhoun and 32 more | 86 min |
| Mar 17, 6:09 PM CDT | Mesoscale Discussion | SPC | Colbert, Franklin, Lamar, Lauderdale, Lawrence, Marion | 66 min |
| Mar 17, 6:48 PM CDT | Tornado Watch | SPC | Autauga, Baldwin, Barbour, Bibb, Blount, Bullock and 44 more | 8 hr |
Nearby
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.