Alert archive / Louisiana / Mesoscale Discussions in 2018

Mesoscale Discussion 228

April 6, 201834 parishes in Louisiana; 22 counties in Mississippi; 4 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 6, 2018, 10:57 PM CDT for 34 parishes in Louisiana; 22 counties in Mississippi; 4 counties in Texas. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: Apr 6, 2018, 10:57 PM CDT (03:57 UTC)
Expired: Apr 7, 2018, 12:30 AM CDT
In force: 93 min
Issued by: the Storm Prediction Center

All 60 counties

Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Jefferson Davis County, MS, Jones County, MS, Lamar County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS, Wilkinson County, MS, Jasper County, TX, Jefferson County, TX, Newton County, TX, Orange County, TX

The radar

The Ft Polk radar (KPOE), 113 km from the middle of the area, began a volume at 03:59 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, 4.0 hours before the alert went out and 130 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: 1528 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 633 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 164 m²/s²
0-3 km storm-relative helicity: 215 m²/s²
Significant tornado parameter: 1.8
Supercell composite: 11.9

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
Apr 6, 8:12 PM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Avoyelles, Beauregard, Calcasieu and 21 more	63 min
Apr 6, 8:53 PM CDT	Severe Thunderstorm Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 33 more	10 hr
Apr 7, 1:37 AM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Calcasieu, Cameron, Iberia, Jefferson Davis and 4 more	83 min
Apr 7, 4:31 AM CDT	Mesoscale Discussion	SPC	Jefferson, Lafourche, Orleans, Saint Bernard, Saint Charles, Saint John the Baptist	59 min
Apr 6, 9:22 PM CDT	Mesoscale Discussion	SPC	Anderson, Falls, Freestone, Henderson, Houston, Leon and 9 more	83 min

Nearby

Mesoscale Discussions in Louisiana, 2018 Mesoscale Discussions in Mississippi, 2018 Mesoscale Discussions in Texas, 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.