Alert archive / Louisiana / Tornado Watches in 2021
Tornado Watch 541
The Storm Prediction Center issued this tornado watch at Oct 27, 2021, 10:08 AM CDT for 12 parishes in Louisiana; 4 counties in Texas. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Oct 27, 2021, 10:08 AM CDT (15:08 UTC)
- Expired
- Oct 27, 2021, 3:13 PM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
Counties Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Red River Parish, LA, Webster Parish, LA, Winn Parish, LA, Harrison County, TX, Marion County, TX, Panola County, TX, Shelby County, TX
The radar
The Shreveport radar (KSHV), 59 km from the middle of the area, began a volume at 15:08 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
- 40%
- One or more gusts of 65 knots or more
- 20%
- 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
- 50%
Warnings issued inside it
6 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 27, 10:44 AM CDT | Severe Thunderstorm Warning | SHV | Caddo | 46 min |
| Oct 27, 11:06 AM CDT | Severe Thunderstorm Warning | SHV | Bossier, Caddo, De Soto, Red River, Sabine | 39 min |
| Oct 27, 11:30 AM CDT | Severe Thunderstorm Warning | SHV | Bossier, Caddo | 45 min |
| Oct 27, 11:40 AM CDT | Severe Thunderstorm Warning | SHV | Bienville, Bossier, Caddo, De Soto, Natchitoches, Red River and 2 more | 65 min |
| Oct 27, 12:29 PM CDT | Severe Thunderstorm Warning | SHV | Grant, Natchitoches, Sabine, Winn | 61 min |
| Oct 27, 1:39 PM CDT | Severe Thunderstorm Warning | SHV | Caldwell, Grant, LaSalle, Winn | 66 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
Shreveport, LA (KSHV), launched 12:00Z, 3.1 hours before the alert went out and 52 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
- 395 J/kg
- Mixed-layer CIN
- -87 J/kg
- Mixed-layer LCL
- 557 m above ground
- 0-6 km bulk shear
- 38 kt
- 0-1 km storm-relative helicity
- 233 m²/s²
- 0-3 km storm-relative helicity
- 175 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.0
The text
As transmitted.
750 WWUS20 KWNS 271504 SEL1 SPC WW 271504 LAZ000-TXZ000-272100- URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 541 NWS Storm Prediction Center Norman OK 1005 AM CDT Wed Oct 27 2021 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Northern Louisiana Extreme northeast Texas * Effective this Wednesday morning and afternoon from 1005 AM until 400 PM CDT. * Primary threats include... A couple tornadoes possible Scattered damaging wind gusts to 70 mph possible SUMMARY...A squall line is expected to intensify some through early afternoon while moving eastward from Texas into Louisiana. The storm environment is favorable for embedded circulations in the line, with an attendant threat for occasional damaging outflow gusts and a couple of mesovortex tornadoes. The tornado watch area is approximately along and 65 statute miles east and west of a line from 40 miles north northeast of Shreveport LA to 30 miles south southwest of Natchitoches LA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). 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 540... AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 0.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 24025. ...Thompson
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 27, 7:36 AM CDT | Mesoscale Discussion | SPC | Acadia, Beauregard, Calcasieu, Cameron, Iberia, Jefferson Davis and 4 more | 84 min |
| Oct 27, 7:55 AM CDT | Tornado Watch | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 13 more | 9 hr |
| Oct 27, 9:44 AM CDT | Mesoscale Discussion | SPC | Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 7 more | 2 hr |
| Oct 27, 10:59 AM CDT | Mesoscale Discussion | SPC | Beauregard, Vernon | 91 min |
| Oct 27, 12:50 PM CDT | Mesoscale Discussion | SPC | Acadia, Ascension, Assumption, Avoyelles, Concordia, East Baton Rouge and 24 more | 85 min |
| Oct 27, 12:52 PM CDT | Mesoscale Discussion | SPC | Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 7 more | 83 min |
| Oct 27, 1:53 PM CDT | Tornado Watch | SPC | Ascension, Assumption, Catahoula, Concordia, East Baton Rouge, East Feliciana and 18 more | 8 hr |
| Oct 27, 3:25 PM CDT | Mesoscale Discussion | SPC | Ascension, Assumption, East Baton Rouge, East Feliciana, Iberville, Jefferson and 13 more | 95 min |
| Oct 27, 5:13 PM CDT | Mesoscale Discussion | SPC | Orleans, Saint Bernard, Saint John the Baptist, Saint Tammany, Tangipahoa, Washington | 2 hr |
| Oct 26, 7:23 PM CDT | Severe Thunderstorm Watch | SPC | Archer, Baylor, Brown, Callahan, Clay, Coke and 45 more | 8 hr |
| Oct 26, 9:37 PM CDT | Mesoscale Discussion | SPC | Archer, Baylor, Callahan, Clay, Coke, Coleman and 26 more | 83 min |
| Oct 27, 1:32 AM CDT | Severe Thunderstorm Watch | SPC | Anderson, Bastrop, Bell, Bexar, Blanco, Bosque and 48 more | 6 hr |
| Oct 27, 1:59 AM CDT | Mesoscale Discussion | SPC | Collin, Cooke, Dallas, Denton, Ellis, Grayson and 8 more | 91 min |
| Oct 27, 5:13 AM CDT | Mesoscale Discussion | SPC | Atascosa, Austin, Bastrop, Bexar, Brazos, Burleson and 22 more | 2 hr |
| Oct 27, 9:08 AM CDT | Mesoscale Discussion | SPC | Hardin, Jasper, Jefferson, Newton, Orange, Tyler | 97 min |
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.