Alert archive / Louisiana / Severe Thunderstorm Watches in 2017

Severe Thunderstorm Watch 294

May 28, 201717 parishes in Louisiana; 12 counties in Texas

The Storm Prediction Center issued this severe thunderstorm watch at May 28, 2017, 5:19 PM CDT for 17 parishes in Louisiana; 12 counties in Texas. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: May 28, 2017, 5:19 PM CDT (22:19 UTC)
Expired: May 28, 2017, 9:46 PM CDT
In force: 4 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 29 counties

Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Sabine Parish, LA, Union Parish, LA, Webster Parish, LA, Winn Parish, LA, Angelina County, TX, Cherokee County, TX, Gregg County, TX, Harrison County, TX, Marion County, TX, Nacogdoches County, TX, Panola County, TX, Rusk County, TX, Sabine County, TX, San Augustine County, TX, Shelby County, TX, Smith County, TX

The radar

The Shreveport radar (KSHV), 39 km from the middle of the area, began a volume at 22:19 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: 5%
Ten or more severe wind reports: 40%
One or more gusts of 65 knots or more: 20%
Ten or more severe hail reports: 30%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 80%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
May 28, 5:29 PM CDT	Severe Thunderstorm Warning	SHV	Harrison	31 min
May 28, 5:37 PM CDT	Severe Thunderstorm Warning	SHV	Cherokee, Nacogdoches, Rusk	38 min
May 28, 5:41 PM CDT	Severe Thunderstorm Warning	SHV	Bossier, Caddo, De Soto	64 min
May 28, 5:46 PM CDT	Severe Thunderstorm Warning	SHV	Bossier, Claiborne, Webster	59 min
May 28, 5:52 PM CDT	Severe Thunderstorm Warning	SHV	Caddo, De Soto	38 min
May 28, 5:54 PM CDT	Tornado Warning	SHV	Caddo, De Soto	25 min
May 28, 6:22 PM CDT	Severe Thunderstorm Warning	SHV	Bossier, Caddo, De Soto, Red River, Sabine, Webster	53 min
May 28, 6:30 PM CDT	Tornado Warning	SHV	De Soto, Sabine	26 min
May 28, 6:32 PM CDT	Flash Flood Warning	SHV	Bienville, Bossier, Caddo, De Soto, Red River, Webster	3 hr
May 28, 6:40 PM CDT	Severe Thunderstorm Warning	SHV	De Soto, Natchitoches, Sabine	50 min
May 28, 6:48 PM CDT	Flash Flood Warning	SHV	Angelina, Cherokee, Nacogdoches, Rusk	3 hr
May 28, 6:51 PM CDT	Severe Thunderstorm Warning	SHV	Bienville, Bossier, Caddo, De Soto, Natchitoches, Red River and 3 more	54 min
May 28, 6:52 PM CDT	Severe Thunderstorm Warning	SHV	Cherokee, Nacogdoches, Rusk	53 min
May 28, 7:02 PM CDT	Flash Flood Warning	SHV	De Soto, Red River, Sabine	3 hr
May 28, 7:09 PM CDT	Severe Thunderstorm Warning	SHV	Natchitoches, Sabine	51 min
May 28, 7:24 PM CDT	Tornado Warning	SHV	Natchitoches, Sabine	51 min
May 28, 7:30 PM CDT	Tornado Warning	SHV	Grant, Natchitoches, Winn	60 min
May 28, 7:43 PM CDT	Severe Thunderstorm Warning	SHV	Bienville, Grant, Jackson, Natchitoches, Winn	62 min
May 28, 8:00 PM CDT	Flash Flood Warning	SHV	Bienville, Bossier, Claiborne, De Soto, Jackson, Lincoln and 6 more	3 hr
May 28, 8:05 PM CDT	Tornado Warning	SHV	Winn	40 min
May 28, 8:18 PM CDT	Tornado Warning	SHV	Grant, Natchitoches	44 min
May 28, 8:30 PM CDT	Tornado Warning	SHV	Caldwell, Grant, LaSalle, Winn	45 min
May 28, 8:39 PM CDT	Severe Thunderstorm Warning	SHV	Caldwell, Grant, Jackson, LaSalle, Natchitoches, Ouachita and 1 more	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 (KBAD), launched 12:00Z, 10.3 hours before the alert went out and 48 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1753 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: -304 m²/s²
0-3 km storm-relative helicity: -56 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.6

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 28, 2:53 AM CDT	Mesoscale Discussion	SPC	Bossier, Caddo, Claiborne, Lincoln, Union, Webster	2 hr
May 28, 10:59 AM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, Calcasieu, Cameron, Iberia, Iberville and 15 more	2 hr
May 28, 5:01 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 9 more	59 min
May 27, 7:12 PM CDT	Mesoscale Discussion	SPC	Dallam, Hansford, Hartley, Ochiltree, Sherman	2 hr
May 27, 9:07 PM CDT	Mesoscale Discussion	SPC	Hansford, Hemphill, Hutchinson, Lipscomb, Ochiltree, Roberts and 1 more	53 min
May 27, 11:47 PM CDT	Mesoscale Discussion	SPC	Clay, Cooke, Fannin, Grayson, Lamar, Montague and 1 more	58 min
May 28, 12:06 AM CDT	Severe Thunderstorm Watch	SPC	Bowie, Collin, Cooke, Denton, Fannin, Grayson and 4 more	5 hr
May 28, 4:59 AM CDT	Mesoscale Discussion	SPC	Bowie, Camp, Cass, Collin, Delta, Denton and 7 more	2 hr
May 28, 1:34 PM CDT	Mesoscale Discussion	SPC	Bastrop, Bell, Bexar, Blanco, Burnet, Caldwell and 18 more	56 min
May 28, 3:09 PM CDT	Severe Thunderstorm Watch	SPC	Anderson, Atascosa, Austin, Bandera, Bastrop, Bell and 58 more	8 hr
May 28, 6:03 PM CDT	Mesoscale Discussion	SPC	Anderson, Bandera, Bastrop, Bell, Bexar, Blanco and 40 more	57 min

Nearby

Severe Thunderstorm Watches in Louisiana, 2017 Severe Thunderstorm Watches in Texas, 2017 Every severe thunderstorm watch in 2017

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.