Alert archive / Louisiana / Severe Thunderstorm Watches in 2018
Severe Thunderstorm Watch 12
The Storm Prediction Center issued this severe thunderstorm watch at Mar 18, 2018, 9:11 PM CDT for 18 parishes in Louisiana; 7 counties in Texas. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 18, 2018, 9:11 PM CDT (02:11 UTC)
- Expired
- Mar 18, 2018, 11:56 PM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 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, De Soto Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Jefferson Davis Parish, LA, LaSalle Parish, LA, Natchitoches Parish, LA, Rapides Parish, LA, Red River Parish, LA, Sabine Parish, LA, Saint Landry Parish, LA, Vernon Parish, LA, Winn Parish, LA, Hardin County, TX, Jasper County, TX, Newton County, TX, Sabine County, TX, San Augustine County, TX, Shelby County, TX, Tyler County, TX
The radar
The Ft Polk radar (KPOE), 24 km from the middle of the area, began a volume at 02:14 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
- 20%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
4 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 18, 9:21 PM CDT | Tornado Warning | SHV | Natchitoches, Sabine | 19 min |
| Mar 18, 9:22 PM CDT | Severe Thunderstorm Warning | SHV | Sabine | 15 min |
| Mar 18, 9:45 PM CDT | Severe Thunderstorm Warning | LCH | Beauregard, Vernon | 45 min |
| Mar 18, 10:11 PM CDT | Severe Thunderstorm Warning | SHV | Grant, Natchitoches, Winn | 49 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 00:00Z, 2.2 hours before the alert went out and 141 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
- 1159 J/kg
- Mixed-layer CIN
- -77 J/kg
- Mixed-layer LCL
- 1060 m above ground
- 0-6 km bulk shear
- 51 kt
- 0-1 km storm-relative helicity
- -31 m²/s²
- 0-3 km storm-relative helicity
- 67 m²/s²
- Significant tornado parameter
- -0.1
- Supercell composite
- -1.1
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 18, 10:55 PM CDT | Mesoscale Discussion | SPC | Allen, Avoyelles, Beauregard, Evangeline, Grant, LaSalle and 2 more | 95 min |
| Mar 18, 7:55 PM CDT | Mesoscale Discussion | SPC | Angelina, Grimes, Hardin, Jasper, Montgomery, Nacogdoches and 7 more | 95 min |
| Mar 19, 1:08 AM CDT | Mesoscale Discussion | SPC | Collin, Cooke, Delta, Denton, Fannin, Grayson and 2 more | 2 hr |
Nearby
Severe Thunderstorm Watches in Louisiana, 2018Severe Thunderstorm Watches in Texas, 2018Every severe thunderstorm 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.