Alert archive / Louisiana / Tornado Watches in 2020

Tornado Watch 124

April 19, 20204 states

The Storm Prediction Center issued this tornado watch at Apr 19, 2020, 9:39 PM CDT for 4 states. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Apr 19, 2020, 9:39 PM CDT (02:39 UTC)
Expired
Apr 20, 2020, 2:55 AM CDT
In force
5 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt
All 37 counties

Baldwin County, AL, Butler County, AL, Clarke County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Escambia County, AL, Mobile County, AL, Monroe County, AL, Washington County, AL, Wilcox County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, Ascension Parish, LA, Assumption Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Washington Parish, LA, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Pearl River County, MS, Perry County, MS, Stone County, MS

The radar

The Mobile radar (KMOB), 24 km from the middle of the area, began a volume at 02:42 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
50%
One or more EF2 to EF5 tornadoes
40%
Ten or more severe wind reports
70%
One or more gusts of 65 knots or more
10%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
90%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 19, 9:41 PM CDTSevere Thunderstorm WarningLIXLivingston, Saint Tammany, Tangipahoa34 min
Apr 19, 9:42 PM CDTSevere Thunderstorm WarningMOBBaldwin, Clarke, Escambia, Mobile19 min
Apr 19, 9:50 PM CDTTornado WarningLIXHancock, Pearl River25 min
Apr 19, 10:12 PM CDTSevere Thunderstorm WarningLIXSaint Tammany33 min
Apr 19, 10:35 PM CDTSevere Thunderstorm WarningMOBConecuh, Covington, Escambia25 min
Apr 19, 10:38 PM CDTSevere Thunderstorm WarningMOBMobile52 min
Apr 19, 10:38 PM CDTSevere Thunderstorm WarningLIXJackson54 min
Apr 19, 10:40 PM CDTSevere Thunderstorm WarningMOBCovington, Crenshaw35 min
Apr 19, 10:41 PM CDTSevere Thunderstorm WarningLIXHancock, Harrison34 min
Apr 19, 10:47 PM CDTTornado WarningMOBCovington28 min
Apr 19, 10:54 PM CDTSevere Thunderstorm WarningMOBMobile51 min
Apr 19, 10:54 PM CDTSevere Thunderstorm WarningMOBCovington36 min
Apr 19, 10:56 PM CDTSevere Thunderstorm WarningLIXSaint Tammany34 min
Apr 19, 11:03 PM CDTTornado WarningMOBMobile27 min
Apr 19, 11:07 PM CDTTornado WarningMOBMobile38 min
Apr 19, 11:14 PM CDTSevere Thunderstorm WarningMOBBaldwin61 min
Apr 19, 11:26 PM CDTTornado WarningMOBBaldwin29 min
Apr 19, 11:29 PM CDTTornado WarningMOBBaldwin31 min
Apr 19, 11:41 PM CDTSevere Thunderstorm WarningMOBEscambia34 min
Apr 19, 11:43 PM CDTSevere Thunderstorm WarningMOBMobile47 min
Apr 19, 11:45 PM CDTTornado WarningMOBBaldwin30 min
Apr 19, 11:55 PM CDTSevere Thunderstorm WarningMOBOkaloosa15 min
Apr 19, 11:58 PM CDTSevere Thunderstorm WarningMOBOkaloosa62 min
Apr 20, 12:01 AM CDTTornado WarningMOBEscambia, Santa Rosa29 min
Apr 20, 12:05 AM CDTSevere Thunderstorm WarningMOBConecuh, Covington, Escambia40 min
Apr 20, 12:10 AM CDTSevere Thunderstorm WarningMOBBaldwin50 min
Apr 20, 12:28 AM CDTSevere Thunderstorm WarningMOBMobile28 min
Apr 20, 12:54 AM CDTSevere Thunderstorm WarningMOBBaldwin66 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

Slidell Radar S, LA (KSIL), launched 00:00Z, 2.7 hours before the alert went out and 140 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, Slidell Radar S, LA at 00:00Z on 2020-04-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2097 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, Slidell Radar S, LA at 00:00Z on 2020-04-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 202 square meters per square second.1939587897Sfc1 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
2097 J/kg
Mixed-layer CIN
-13 J/kg
Mixed-layer LCL
819 m above ground
0-6 km bulk shear
65 kt
0-1 km storm-relative helicity
202 m²/s²
0-3 km storm-relative helicity
227 m²/s²
Significant tornado parameter
2.5
Supercell composite
9.5

Open this sounding in Storm Lab

The text

As transmitted.

051 
WWUS20 KWNS 200233
SEL4  
SPC WW 200233
ALZ000-FLZ000-LAZ000-MSZ000-CWZ000-200900-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 124
NWS Storm Prediction Center Norman OK
935 PM CDT Sun Apr 19 2020

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Southern Alabama
  Florida Panhandle
  Southeast Louisiana
  Southeast Mississippi
  Coastal Waters

* Effective this Sunday night and Monday morning from 935 PM
  until 400 AM CDT.

* Primary threats include...
  A few tornadoes and a couple intense tornadoes possible
  Scattered damaging wind gusts to 70 mph likely
  Isolated large hail events to 1.5 inches in diameter possible

SUMMARY...Clusters of storms including bowing segments and a few
semi-discrete supercells will cross the region late this evening
into the overnight. Damaging winds will be the most common severe
risk, but a few tornadoes could occur, potentially including a
strong/intense tornado risk given the increasing low-level
shear/SRH.

The tornado watch area is approximately along and 65 statute miles
north and south of a line from 35 miles north northeast of Crestview
FL to 35 miles west northwest of Houma LA. For a complete depiction
of the watch see the associated watch outline update (WOUS64 KWNS
WOU4).

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 122...WW 123...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 1.5 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 600. Mean
storm motion vector 26040.

...Guyer

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 19, 8:25 PM CDTMesoscale DiscussionSPCBarbour, Bullock, Crenshaw, Dale, Henry, Macon and 3 more65 min
Apr 19, 9:07 PM CDTMesoscale DiscussionSPCMobile83 min
Apr 19, 9:53 PM CDTMesoscale DiscussionSPCDale, Geneva, Henry, Houston67 min
Apr 19, 10:13 PM CDTTornado WatchSPCBarbour, Coffee, Dale, Geneva, Henry, Houston and 1 more10 hr
Apr 20, 12:52 AM CDTMesoscale DiscussionSPCAlachua, Baker, Bradford, Clay, Columbia, Duval and 6 more83 min
Apr 20, 1:19 AM CDTTornado WatchSPCAlachua, Baker, Bradford, Clay, Columbia, Duval and 9 more9 hr
Apr 20, 5:19 AM CDTMesoscale DiscussionSPCAlachua, Baker, Bradford, Citrus, Clay, Columbia and 16 more86 min
Apr 20, 6:02 AM CDTSevere Thunderstorm WatchSPCBrevard, Citrus, Hardee, Hernando, Hillsborough, Lake and 11 more8 hr
Apr 20, 7:18 AM CDTMesoscale DiscussionSPCAlachua, Citrus, Flagler, Levy, Marion, Putnam and 2 more87 min
Apr 20, 10:06 AM CDTMesoscale DiscussionSPCBrevard, Hardee, Hernando, Hillsborough, Indian River, Lake and 10 more114 min
Apr 20, 1:00 PM CDTMesoscale DiscussionSPCDeSoto, Hardee, Highlands, Indian River, Manatee, Okeechobee and 4 more90 min
Apr 19, 7:42 PM CDTMesoscale DiscussionSPCForrest, Greene, Lamar, Perry33 min

Nearby

Tornado Watches in Louisiana, 2020Tornado Watches in Alabama, 2020Tornado Watches in Mississippi, 2020Every tornado watch in 2020

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.