Alert archive / Louisiana / Mesoscale Discussions in 2015

Mesoscale Discussion 2092

December 27, 20154 states

The Storm Prediction Center issued this mesoscale discussion at Dec 27, 2015, 8:59 PM CST for 4 states. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Dec 27, 2015, 8:59 PM CST (02:59 UTC)
Expired: Dec 27, 2015, 10:30 PM CST
In force: 91 min
Issued by: the Storm Prediction Center

All 44 counties

Ashley County, AR, Chicot County, AR, Union County, AR, Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Claiborne Parish, LA, Concordia Parish, LA, De Soto Parish, LA, East Carroll Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, Jefferson Davis Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Saint Landry Parish, LA, Tensas Parish, LA, Union Parish, LA, Vernon Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Adams County, MS, Jasper County, TX, Newton County, TX, Sabine County, TX, San Augustine County, TX

The radar

The Ft Polk radar (KPOE), 53 km from the middle of the area, began a volume at 03:01 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 573Dec 27, 9:55 PM CST

The nearest sounding before it

Shreveport, LA (KBAD), launched 00:00Z, 3.0 hours before the alert went out and 144 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: 692 J/kg
Mixed-layer CIN: -10 J/kg
Mixed-layer LCL: 1047 m above ground
0-6 km bulk shear: 61 kt
0-1 km storm-relative helicity: 360 m²/s²
0-3 km storm-relative helicity: 462 m²/s²
Significant tornado parameter: 1.9
Supercell composite: 9.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 27, 7:11 PM CST	Mesoscale Discussion	SPC	Ashley, Bradley, Calhoun, Columbia, Drew, Lafayette and 4 more	94 min
Dec 27, 9:57 PM CST	Tornado Watch	SPC	Ashley, Chicot, Columbia, Union	7 hr
Dec 27, 11:49 PM CST	Mesoscale Discussion	SPC	Ashley, Chicot, Union	86 min
Dec 28, 2:03 AM CST	Mesoscale Discussion	SPC	Arkansas, Ashley, Bradley, Chicot, Desha, Drew and 1 more	117 min
Dec 28, 2:23 AM CST	Tornado Watch	SPC	Lee, Phillips	8 hr
Dec 28, 5:14 AM CST	Mesoscale Discussion	SPC	Crittenden, Cross, Lee, Mississippi, Monroe, Phillips and 3 more	2 hr
Dec 27, 10:41 PM CST	Mesoscale Discussion	SPC	Archer, Armstrong, Baylor, Borden, Briscoe, Brown and 56 more	4 hr
Dec 28, 2:41 AM CST	Mesoscale Discussion	SPC	Wichita	6 hr

Nearby

Mesoscale Discussions in Louisiana, 2015 Mesoscale Discussions in Texas, 2015 Mesoscale Discussions in Arkansas, 2015 Every mesoscale discussion in 2015

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.