Alert archive / Louisiana / Mesoscale Discussions in 2016

Mesoscale Discussion 1893

December 17, 2016Ashley County, Columbia County, Union County, Arkansas; 25 parishes in Louisiana; 17 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Dec 17, 2016, 6:44 PM CST for Ashley County, Columbia County, Union County, Arkansas; 25 parishes in Louisiana; 17 counties in Texas. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Dec 17, 2016, 6:44 PM CST (00:44 UTC)
Expired
Dec 17, 2016, 9:15 PM CST
In force
3 hr
Issued by
the Storm Prediction Center
Chance of a watch
40%
All 45 counties

Ashley County, AR, Columbia County, AR, Union County, AR, Allen Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Union Parish, LA, Vernon Parish, LA, Webster Parish, LA, Winn Parish, LA, Angelina County, TX, Hardin County, TX, Houston County, TX, Jasper County, TX, Liberty County, TX, Montgomery 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), 78 km from the middle of the area, began a volume at 00:47 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.

The nearest sounding before it

Shreveport, LA (KBAD), launched 00:00Z, 0.7 hours before the alert went out and 76 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, Shreveport, LA at 00:00Z on 2016-12-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1326 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, Shreveport, LA at 00:00Z on 2016-12-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 310 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
1326 J/kg
Mixed-layer CIN
-5 J/kg
Mixed-layer LCL
760 m above ground
0-6 km bulk shear
69 kt
0-1 km storm-relative helicity
310 m²/s²
0-3 km storm-relative helicity
308 m²/s²
Significant tornado parameter
2.8
Supercell composite
11.1

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.

IssuedProductOfficeCountiesLasted
Dec 17, 8:28 PM CSTMesoscale DiscussionSPCArkansas, Cleveland, Desha, Lincoln, Phillips62 min
Dec 17, 8:58 PM CSTTornado WatchSPCAshley, Bradley, Chicot, Desha, Drew, Phillips and 1 more6 hr
Dec 17, 11:48 PM CSTMesoscale DiscussionSPCAllen, Avoyelles, Caldwell, Catahoula, Concordia, East Carroll and 8 more87 min

Nearby

Mesoscale Discussions in Louisiana, 2016Mesoscale Discussions in Texas, 2016Mesoscale Discussions in Arkansas, 2016Every 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.