Alert archive / Louisiana / Tornado Watches in 2021
Tornado Watch 30
The Storm Prediction Center issued this tornado watch at Mar 17, 2021, 11:53 AM CDT for 13 parishes in Louisiana; 6 counties in Texas. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 17, 2021, 11:53 AM CDT (16:53 UTC)
- Expired
- Mar 17, 2021, 6:00 PM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2.5 in
- Strongest gust expected
- 65 kt
Counties Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Evangeline Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Rapides Parish, LA, Saint Landry Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, Hardin County, TX, Jasper County, TX, Jefferson County, TX, Newton County, TX, Orange County, TX, Tyler County, TX
The radar
The Lake Charles radar (KLCH), 62 km from the middle of the area, began a volume at 16:55 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
- 60%
- One or more EF2 to EF5 tornadoes
- 40%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 40%
- 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.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 17, 1:24 PM CDT | Severe Thunderstorm Warning | LCH | Acadia, Cameron, Jefferson Davis, Vermilion | 36 min |
| Mar 17, 3:58 PM CDT | Severe Thunderstorm Warning | LCH | Cameron, Vermilion | 62 min |
| Mar 17, 4:19 PM CDT | Severe Thunderstorm Warning | LCH | Acadia, Cameron, Jefferson Davis, Vermilion | 44 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
Lake Charles Mun, LA (KLCH), launched 12:00Z, 4.9 hours before the alert went out and 62 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
- 458 J/kg
- Mixed-layer CIN
- -397 J/kg
- Mixed-layer LCL
- 1132 m above ground
- 0-6 km bulk shear
- 47 kt
- 0-1 km storm-relative helicity
- 158 m²/s²
- 0-3 km storm-relative helicity
- 247 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.2
The text
As transmitted.
511
WWUS20 KWNS 171650
SEL0
SPC WW 171650
LAZ000-TXZ000-CWZ000-172300-
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 30
NWS Storm Prediction Center Norman OK
1155 AM CDT Wed Mar 17 2021
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Southwest Louisiana
Far southeast Texas
Coastal Waters
* Effective this Wednesday morning and evening from 1155 AM until
600 PM CDT.
* Primary threats include...
A few tornadoes likely with a couple intense tornadoes possible
Scattered damaging winds and isolated significant gusts to 75
mph possible
Scattered large hail and isolated very large hail events to 2.5
inches in diameter possible
SUMMARY...A few discrete supercells should develop along and just
ahead of the cold front pushing east from southeast Texas. The
greatest tornado threat is expected towards central Louisiana during
the late afternoon.
The tornado watch area is approximately along and 70 statute miles
east and west of a line from 30 miles northeast of Fort Polk LA to
50 miles south southwest of Lake Charles LA. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU0).
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 26...WW 27...WW 28...WW
29...
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2.5 inches. Extreme turbulence and surface wind
gusts to 65 knots. A few cumulonimbi with maximum tops to 550. Mean
storm motion vector 24035.
...GramsSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 17, 1:32 AM CDT | Mesoscale Discussion | SPC | Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 6 more | 118 min |
| Mar 17, 4:04 AM CDT | Mesoscale Discussion | SPC | Bossier, Caddo | 86 min |
| Mar 17, 4:37 AM CDT | Severe Thunderstorm Watch | SPC | Bossier, Caddo | 5 hr |
| Mar 17, 6:40 AM CDT | Mesoscale Discussion | SPC | Bossier, Caddo, Claiborne, Webster | 95 min |
| Mar 17, 8:43 AM CDT | Tornado Watch | SPC | Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 8 more | 4 hr |
| Mar 17, 11:35 AM CDT | Mesoscale Discussion | SPC | Allen, Beauregard, Bienville, Calcasieu, Cameron, De Soto and 8 more | 85 min |
| Mar 17, 12:15 PM CDT | Mesoscale Discussion | SPC | Caldwell, Catahoula, East Carroll, Franklin, Jackson, LaSalle and 9 more | 90 min |
| Mar 17, 12:57 PM CDT | Tornado Watch | SPC | Bienville, Caldwell, Catahoula, Concordia, East Carroll, Franklin and 15 more | 6 hr |
| Mar 17, 1:45 PM CDT | Mesoscale Discussion | SPC | Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 18 more | 90 min |
| Mar 17, 2:38 PM CDT | Tornado Watch | SPC | Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 19 more | 8 hr |
| Mar 17, 2:56 PM CDT | Mesoscale Discussion | SPC | Caldwell, Catahoula, Concordia, East Carroll, Franklin, Grant and 7 more | 94 min |
| Mar 16, 7:49 PM CDT | Severe Thunderstorm Watch | SPC | Collingsworth, Donley, Gray, Hemphill, Lipscomb, Roberts and 1 more | 7 hr |
| Mar 16, 9:27 PM CDT | Mesoscale Discussion | SPC | Archer, Baylor, Brown, Callahan, Coke, Coleman and 30 more | 93 min |
| Mar 16, 10:26 PM CDT | Severe Thunderstorm Watch | SPC | Bell, Bosque, Brown, Callahan, Coke, Coleman and 44 more | 7 hr |
| Mar 17, 2:20 AM CDT | Mesoscale Discussion | SPC | Brown, Callahan, Coleman, Comanche, Eastland, Erath and 6 more | 85 min |
| Mar 17, 4:38 AM CDT | Mesoscale Discussion | SPC | Armstrong, Carson, Dallam, Deaf Smith, Gray, Hansford and 11 more | 6 hr |
Nearby
Tornado Watches in Louisiana, 2021Tornado Watches in Texas, 2021Every tornado watch in 2021
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.