Alert archive / Louisiana / Tornado Watches in 2018
Tornado Watch 3
The Storm Prediction Center issued this tornado watch at Feb 21, 2018, 9:48 AM CST for 23 parishes in Louisiana; Newton County, Orange County, Texas. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 21, 2018, 9:48 AM CST (15:48 UTC)
- Expired
- Feb 21, 2018, 5:00 PM CST
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
All 25 counties
Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, Jefferson Davis Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Richland Parish, LA, Saint Landry Parish, LA, Tensas Parish, LA, Vernon Parish, LA, Winn Parish, LA, Newton County, TX, Orange County, TX
The radar
The Ft Polk radar (KPOE), 79 km from the middle of the area, began a volume at 15:47 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
- 20%
- 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
- 50%
Warnings issued inside it
21 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 21, 10:11 AM CST | Tornado Warning | LCH | Rapides, Vernon | 15 min |
| Feb 21, 10:29 AM CST | Flash Flood Warning | SHV | Grant, Natchitoches, Winn | 3 hr |
| Feb 21, 10:43 AM CST | Flash Flood Warning | SHV | Grant, Natchitoches, Winn | 3 hr |
| Feb 21, 10:49 AM CST | Severe Thunderstorm Warning | SHV | Grant, Natchitoches | 41 min |
| Feb 21, 10:52 AM CST | Flash Flood Warning | LCH | Vernon | 4 hr |
| Feb 21, 11:16 AM CST | Tornado Warning | SHV | Grant, Winn | 29 min |
| Feb 21, 11:19 AM CST | Flash Flood Warning | LCH | Rapides | 3 hr |
| Feb 21, 11:50 AM CST | Severe Thunderstorm Warning | SHV | Grant, Winn | 25 min |
| Feb 21, 11:58 AM CST | Tornado Warning | SHV | Grant, LaSalle, Winn | 32 min |
| Feb 21, 12:23 PM CST | Flash Flood Warning | SHV | Grant, LaSalle | 3 hr |
| Feb 21, 12:31 PM CST | Severe Thunderstorm Warning | SHV | Caldwell, Jackson, LaSalle, Winn | 44 min |
| Feb 21, 12:36 PM CST | Flash Flood Warning | SHV | De Soto, Natchitoches, Red River, Sabine | 3 hr |
| Feb 21, 12:44 PM CST | Tornado Warning | SHV | Caldwell, LaSalle | 31 min |
| Feb 21, 12:48 PM CST | Severe Thunderstorm Warning | JAN | Catahoula, Concordia, Franklin, Richland | 42 min |
| Feb 21, 1:01 PM CST | Tornado Warning | SHV | Caldwell, LaSalle | 29 min |
| Feb 21, 1:28 PM CST | Severe Thunderstorm Warning | JAN | Catahoula, Franklin, Tensas | 62 min |
| Feb 21, 1:52 PM CST | Flash Flood Warning | JAN | Catahoula, Franklin, Tensas | 3 hr |
| Feb 21, 2:28 PM CST | Severe Thunderstorm Warning | JAN | Franklin, Tensas | 32 min |
| Feb 21, 2:46 PM CST | Flash Flood Warning | LCH | Rapides, Vernon | 5 hr |
| Feb 21, 2:53 PM CST | Severe Thunderstorm Warning | JAN | Madison | 36 min |
| Feb 21, 3:02 PM CST | Flash Flood Warning | SHV | Bienville, Grant, Jackson, Natchitoches, Winn | 11 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
Lake Charles Mun, LA (KLCH), launched 12:00Z, 3.8 hours before the alert went out and 173 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
- 1458 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 474 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 203 m²/s²
- 0-3 km storm-relative helicity
- 188 m²/s²
- Significant tornado parameter
- 1.3
- Supercell composite
- 10.0
The text
As transmitted.
089 WWUS20 KWNS 211546 SEL3 SPC WW 211546 LAZ000-TXZ000-212300- URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 3 NWS Storm Prediction Center Norman OK 950 AM CST Wed Feb 21 2018 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Southwest into northeast Louisiana Extreme southeast Texas * Effective this Wednesday morning and afternoon from 950 AM until 500 PM CST. * Primary threats include... A couple tornadoes possible Isolated damaging wind gusts to 70 mph possible SUMMARY...Clusters of thunderstorms will persist through the day from extreme southeast Texas northeastward across Louisiana, in advance of a slow-moving cold front. The storm environment will be favorable for a few supercells through the day, with an attendant threat for a couple of tornadoes and isolated damaging winds. The tornado watch area is approximately along and 55 statute miles east and west of a line from 70 miles north northeast of Alexandria LA to 5 miles south of Lake Charles LA. 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. && 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 450. Mean storm motion vector 22020. ...Thompson
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 21, 9:07 AM CST | Mesoscale Discussion | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 12 more | 113 min |
| Feb 21, 12:28 PM CST | Mesoscale Discussion | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 17 more | 92 min |
| Feb 21, 3:03 PM CST | Mesoscale Discussion | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 20 more | 117 min |
| Feb 21, 7:57 AM CST | Mesoscale Discussion | SPC | Archer, Baylor, Borden, Callahan, Childress, Clay and 35 more | 4 hr |
| Feb 21, 12:44 PM CST | Mesoscale Discussion | SPC | Clay, Cooke, Denton, Jack, Montague, Palo Pinto and 1 more | 4 hr |
Nearby
Tornado Watches in Louisiana, 2018Tornado Watches in Texas, 2018Every tornado watch in 2018
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.