Alert archive / Texas / Mesoscale Discussions in 2016

Mesoscale Discussion 1826

November 28, 20164 counties in Arkansas; 7 parishes in Louisiana; 18 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Nov 28, 2016, 7:40 AM CST for 4 counties in Arkansas; 7 parishes in Louisiana; 18 counties in Texas. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Nov 28, 2016, 7:40 AM CST (13:40 UTC)
Expired: Nov 28, 2016, 10:15 AM CST
In force: 3 hr
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 29 counties

Columbia County, AR, Hempstead County, AR, Lafayette County, AR, Miller County, AR, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Red River Parish, LA, Sabine Parish, LA, Webster Parish, LA, Angelina County, TX, Cass County, TX, Cherokee County, TX, Gregg County, TX, Harrison County, TX, Houston County, TX, Marion County, TX, Nacogdoches County, TX, Panola County, TX, Polk County, TX, Rusk County, TX, Sabine County, TX, San Augustine County, TX, Shelby County, TX, Smith County, TX, Trinity County, TX, Tyler County, TX, Upshur County, TX

The radar

The Shreveport radar (KSHV), 59 km from the middle of the area, began a volume at 13:43 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 501Nov 28, 11:05 AM CST

The nearest sounding before it

Shreveport, LA (KBAD), launched 12:00Z, 1.7 hours before the alert went out and 68 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: 14 J/kg
Mixed-layer CIN: -326 J/kg
Mixed-layer LCL: 701 m above ground
0-6 km bulk shear: 70 kt
0-1 km storm-relative helicity: 499 m²/s²
0-3 km storm-relative helicity: 482 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

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
Nov 28, 11:08 AM CST	Tornado Watch	SPC	Columbia, Lafayette, Union	6 hr
Nov 28, 1:02 PM CST	Mesoscale Discussion	SPC	Bradley	118 min
Nov 28, 10:10 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 16 more	2 hr
Nov 28, 2:23 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 27 more	2 hr
Nov 28, 2:49 PM CST	Tornado Watch	SPC	Ascension, Catahoula, Concordia, East Baton Rouge, East Carroll, East Feliciana and 13 more	6 hr
Nov 28, 5:07 PM CST	Mesoscale Discussion	SPC	East Baton Rouge, East Feliciana, Saint Helena, Tangipahoa, Washington, West Baton Rouge and 1 more	83 min
Nov 27, 11:34 PM CST	Mesoscale Discussion	SPC	Archer, Clay, Collin, Cooke, Delta, Denton and 14 more	2 hr
Nov 27, 11:52 PM CST	Severe Thunderstorm Watch	SPC	Clay, Collin, Cooke, Denton, Fannin, Grayson and 5 more	6 hr

Nearby

Mesoscale Discussions in Texas, 2016 Mesoscale Discussions in Louisiana, 2016 Mesoscale Discussions in Arkansas, 2016 Every mesoscale discussion in 2016

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.