Alert archive / Texas / Mesoscale Discussions in 2019

Mesoscale Discussion 682

May 18, 201913 parishes in Louisiana; 15 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 18, 2019, 11:53 PM CDT for 13 parishes in Louisiana; 15 counties in Texas. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued: May 18, 2019, 11:53 PM CDT (04:53 UTC)
Expired: May 19, 2019, 1:30 AM CDT
In force: 97 min
Issued by: the Storm Prediction Center

All 28 counties

Bienville Parish, LA, Caldwell Parish, LA, De Soto Parish, LA, Grant Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Sabine Parish, LA, Union Parish, LA, Vernon Parish, LA, Winn Parish, LA, Angelina County, TX, Houston County, TX, Jasper County, TX, Madison County, TX, Nacogdoches County, TX, Newton County, TX, Panola County, TX, Polk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX

The radar

The Shreveport radar (KSHV), 103 km from the middle of the area, began a volume at 04:54 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.

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Tornado Watch 191May 19, 1:45 AM CDT

The nearest sounding before it

Shreveport, LA (KBAD), launched 00:00Z, 4.9 hours before the alert went out and 108 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: 1844 J/kg
Mixed-layer CIN: -15 J/kg
Mixed-layer LCL: 1157 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 132 m²/s²
0-3 km storm-relative helicity: 197 m²/s²
Significant tornado parameter: 1.5
Supercell composite: 10.6

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 18, 7:08 PM CDT	Tornado Watch	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more	7 hr
May 19, 1:02 AM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 16 more	58 min
May 19, 1:47 AM CDT	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 49 more	9 hr
May 19, 7:50 AM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 17 more	85 min
May 19, 3:49 PM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 12 more	86 min
May 18, 7:13 PM CDT	Mesoscale Discussion	SPC	Anderson, Bastrop, Bell, Brazos, Burleson, Cherokee and 19 more	62 min
May 18, 10:16 PM CDT	Tornado Watch	SPC	Hardin, Houston, Jasper, Madison, Newton, Polk and 4 more	6 hr
May 19, 4:43 AM CDT	Mesoscale Discussion	SPC	Kinney, Maverick, Uvalde, Zavala	3 hr

Nearby

Mesoscale Discussions in Texas, 2019 Mesoscale Discussions in Louisiana, 2019 Every mesoscale discussion 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; radar from the NEXRAD Level II archive.