Alert archive / Louisiana / Mesoscale Discussions in 2018

Mesoscale Discussion 1608

October 31, 20184 counties in Arkansas; 31 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Oct 31, 2018, 11:52 PM CDT for 4 counties in Arkansas; 31 parishes in Louisiana. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued: Oct 31, 2018, 11:52 PM CDT (04:52 UTC)
Expired: Nov 1, 2018, 12:45 AM CDT
In force: 53 min
Issued by: the Storm Prediction Center

All 35 counties

Ashley County, AR, Chicot County, AR, Columbia County, AR, Union County, AR, Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Cameron Parish, LA, Catahoula Parish, LA, Claiborne Parish, LA, Concordia Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, Jefferson Davis Parish, LA, Lafayette 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, Saint Landry Parish, LA, Union Parish, LA, Vernon Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA

The radar

The Ft Polk radar (KPOE), 22 km from the middle of the area, began a volume at 04:55 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 nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 4.9 hours before the alert went out and 133 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: 1529 J/kg
Mixed-layer CIN: -5 J/kg
Mixed-layer LCL: 727 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 167 m²/s²
0-3 km storm-relative helicity: 167 m²/s²
Significant tornado parameter: 1.3
Supercell composite: 7.2

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
Oct 31, 8:14 PM CDT	Tornado Watch	SPC	Ashley, Chicot, Union	8 hr
Oct 31, 11:07 PM CDT	Tornado Watch	SPC	Phillips	9 hr
Nov 1, 1:19 AM CDT	Mesoscale Discussion	SPC	Chicot	116 min
Nov 1, 1:41 AM CDT	Mesoscale Discussion	SPC	Crittenden, Lee, Mississippi, St. Francis	3 hr
Oct 31, 7:28 PM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Bienville, Calcasieu and 20 more	92 min
Oct 31, 10:01 PM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberville, Livingston and 9 more	89 min
Nov 1, 4:30 AM CDT	Mesoscale Discussion	SPC	Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 5 more	2 hr

Nearby

Mesoscale Discussions in Louisiana, 2018 Mesoscale Discussions in Arkansas, 2018 Every mesoscale discussion in 2018

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.