Alert archive / Louisiana / Mesoscale Discussions in 2020

Mesoscale Discussion 1813

November 25, 202021 parishes in Louisiana; 7 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Nov 25, 2020, 7:47 AM CST for 21 parishes in Louisiana; 7 counties in Mississippi. It was in force for 118 min.

The area

The outline as issued.

The facts

Issued: Nov 25, 2020, 7:47 AM CST (13:47 UTC)
Expired: Nov 25, 2020, 9:45 AM CST
In force: 118 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 20%

All 28 counties

Acadia Parish, LA, Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Lafayette Parish, LA, Livingston Parish, LA, Pointe Coupee Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Vermilion Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Franklin County, MS, Lawrence County, MS, Lincoln County, MS, Pike County, MS, Walthall County, MS, Wilkinson County, MS

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 1.8 hours before the alert went out and 147 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: 1101 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 560 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 343 m²/s²
0-3 km storm-relative helicity: 342 m²/s²
Significant tornado parameter: 2.3
Supercell composite: 9.9

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 24, 8:29 PM CST	Severe Thunderstorm Watch	SPC	Bossier, Caddo	6 hr
Nov 24, 11:07 PM CST	Mesoscale Discussion	SPC	Bossier, Caddo	83 min
Nov 25, 1:17 AM CST	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 14 more	118 min
Nov 25, 12:44 PM CST	Mesoscale Discussion	SPC	Assumption, Saint James, Saint John the Baptist, Saint Tammany	2 hr

Nearby

Mesoscale Discussions in Louisiana, 2020 Mesoscale Discussions in Mississippi, 2020 Every mesoscale discussion in 2020

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.