Alert archive / Louisiana / Tornado Watches in 2019

Tornado Watch 82

April 18, 201937 parishes in Louisiana; 20 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Apr 18, 2019, 10:35 AM CDT for 37 parishes in Louisiana; 20 counties in Mississippi. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued
Apr 18, 2019, 10:35 AM CDT (15:35 UTC)
Expired
Apr 18, 2019, 7:00 PM CDT
In force
8 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
65 kt
All 57 counties

Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Cameron Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Carroll Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Madison Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Richland Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Tensas Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA, West Baton Rouge Parish, LA, West Carroll Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Copiah County, MS, Franklin County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Lawrence County, MS, Lincoln County, MS, Madison County, MS, Pike County, MS, Rankin County, MS, Sharkey County, MS, Simpson County, MS, Warren County, MS, Wilkinson County, MS, Yazoo County, MS

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
80%
One or more gusts of 65 knots or more
40%
Ten or more severe hail reports
20%
One or more hailstones of 2 inches or more
10%
Six or more combined severe hail and wind reports
95%

Warnings issued inside it

35 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Apr 18, 11:00 AM CDTSevere Thunderstorm WarningLCHAcadia, Allen, Avoyelles, Evangeline, Rapides, Saint Landry45 min
Apr 18, 11:06 AM CDTTornado WarningLCHAvoyelles, Evangeline, Saint Landry24 min
Apr 18, 11:49 AM CDTSevere Thunderstorm WarningJANCatahoula, Concordia, Franklin56 min
Apr 18, 12:02 PM CDTFlash Flood WarningLCHAcadia, Evangeline, Jefferson Davis, Saint Landry3 hr
Apr 18, 12:03 PM CDTSevere Thunderstorm WarningLCHAcadia, Avoyelles, Lafayette, Saint Landry42 min
Apr 18, 12:22 PM CDTSevere Thunderstorm WarningLIXAscension, East Baton Rouge, Iberville, West Baton Rouge22 min
Apr 18, 12:30 PM CDTSevere Thunderstorm WarningJANCatahoula, Concordia, Franklin, Tensas60 min
Apr 18, 12:35 PM CDTTornado WarningJANConcordia31 min
Apr 18, 12:35 PM CDTFlash Flood WarningLCHAvoyelles2 hr
Apr 18, 12:45 PM CDTSevere Thunderstorm WarningLIXPointe Coupee, West Feliciana30 min
Apr 18, 12:47 PM CDTSevere Thunderstorm WarningLIXAscension, Livingston, Tangipahoa26 min
Apr 18, 1:01 PM CDTSevere Thunderstorm WarningJANMadison74 min
Apr 18, 1:13 PM CDTTornado WarningJANClaiborne, Jefferson46 min
Apr 18, 1:22 PM CDTFlash Flood WarningLIXPointe Coupee, West Feliciana3 hr
Apr 18, 1:22 PM CDTSevere Thunderstorm WarningLIXEast Feliciana, Saint Helena, West Feliciana53 min
Apr 18, 1:38 PM CDTSevere Thunderstorm WarningJANCopiah, Hinds, Warren82 min
Apr 18, 1:41 PM CDTTornado WarningLIXEast Feliciana34 min
Apr 18, 1:43 PM CDTSevere Thunderstorm WarningJANLincoln77 min
Apr 18, 1:43 PM CDTTornado WarningJANCopiah, Hinds62 min
Apr 18, 1:57 PM CDTFlash Flood WarningLCHLafayette, Saint Landry, Saint Martin3 hr
Apr 18, 1:57 PM CDTTornado WarningJANFranklin, Lincoln63 min
Apr 18, 2:07 PM CDTSevere Thunderstorm WarningLIXAmite, Pike23 min
Apr 18, 2:11 PM CDTFlash Flood WarningJANHinds, Issaquena, Madison, Warren3 hr
Apr 18, 2:12 PM CDTTornado WarningLIXAmite, Pike33 min
Apr 18, 2:16 PM CDTSevere Thunderstorm WarningJANMadison, Rankin, Simpson74 min
Apr 18, 2:26 PM CDTTornado WarningJANLawrence, Lincoln49 min
Apr 18, 2:30 PM CDTSevere Thunderstorm WarningJANJefferson Davis, Lawrence, Marion75 min
Apr 18, 2:37 PM CDTTornado WarningJANHinds, Madison, Rankin53 min
Apr 18, 2:40 PM CDTTornado Warning Tornado observedJANRankin, Simpson65 min
Apr 18, 3:09 PM CDTSevere Thunderstorm WarningLIXLivingston, Saint Helena, Tangipahoa, Washington36 min
Apr 18, 3:21 PM CDTFlash Flood WarningJANLeake, Madison, Rankin, Scott3 hr
Apr 18, 3:26 PM CDTTornado Warning Tornado observedJANLeake, Madison, Rankin, Scott64 min
Apr 18, 3:28 PM CDTSevere Thunderstorm WarningJANLeake, Madison, Neshoba, Rankin77 min
Apr 18, 3:31 PM CDTTornado WarningLIXTangipahoa, Washington29 min
Apr 18, 3:44 PM CDTTornado WarningLIXTangipahoa, Washington31 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, 3.6 hours before the alert went out and 174 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.

Skew-T log-pSkew-T log-p diagram, Lake Charles Mun, LA at 12:00Z on 2019-04-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1465 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lake Charles Mun, LA at 12:00Z on 2019-04-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 204 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
1465 J/kg
Mixed-layer CIN
-17 J/kg
Mixed-layer LCL
507 m above ground
0-6 km bulk shear
48 kt
0-1 km storm-relative helicity
204 m²/s²
0-3 km storm-relative helicity
152 m²/s²
Significant tornado parameter
1.6
Supercell composite
11.5

Open this sounding in Storm Lab

The text

As transmitted.

850 
WWUS20 KWNS 181533
SEL2  
SPC WW 181533
LAZ000-MSZ000-CWZ000-190000-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 82
NWS Storm Prediction Center Norman OK
1035 AM CDT Thu Apr 18 2019

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Louisiana
  Western Mississippi
  Coastal Waters

* Effective this Thursday morning and evening from 1035 AM until
  700 PM CDT.

* Primary threats include...
  A few tornadoes likely with a couple intense tornadoes possible
  Widespread damaging winds likely with isolated significant gusts
    to 75 mph possible
  Isolated large hail events to 1.5 inches in diameter possible

SUMMARY...Clusters of strong thunderstorms are expected to intensify
by early afternoon and spread east-northeast across the Lower
Mississippi Valley. Tornadoes and damaging winds are the primary
hazards.

The tornado watch area is approximately along and 65 statute miles
east and west of a line from 20 miles southeast of Intracoastal City
LA to 95 miles north northeast of Natchez MS. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU2).

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 1.5 inches. Extreme turbulence and surface wind
gusts to 65 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 21030.

...Grams

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 18, 12:54 AM CDTMesoscale DiscussionSPCBienville, Bossier, Caddo, De Soto, Natchitoches, Red River and 2 more66 min
Apr 18, 1:09 AM CDTSevere Thunderstorm WatchSPCBossier, Caddo, De Soto, Sabine, Webster7 hr
Apr 18, 3:51 AM CDTMesoscale DiscussionSPCBeauregard, Bienville, Bossier, Caddo, Claiborne, De Soto and 12 more114 min
Apr 18, 6:36 AM CDTMesoscale DiscussionSPCAcadia, Allen, Beauregard, Bienville, Calcasieu, Cameron and 9 more84 min
Apr 18, 9:50 AM CDTMesoscale DiscussionSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Cameron and 25 more85 min
Apr 18, 12:42 PM CDTMesoscale DiscussionSPCAscension, East Baton Rouge, Livingston, Orleans, Saint Charles, Saint Helena and 5 more2 hr
Apr 18, 1:41 PM CDTTornado WatchSPCJefferson, Orleans, Plaquemines, Saint Bernard, Saint Tammany, Washington7 hr
Apr 18, 2:46 PM CDTMesoscale DiscussionSPCAscension, Assumption, East Baton Rouge, Iberville, Lafourche, Livingston and 10 more89 min

Nearby

Tornado Watches in Louisiana, 2019Tornado Watches in Mississippi, 2019Every tornado watch in 2019

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.