Alert archive / Louisiana / Mesoscale Discussions in 2015

Mesoscale Discussion 480

April 27, 201532 parishes in Louisiana; 6 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2015, 7:44 AM CDT for 32 parishes in Louisiana; 6 counties in Mississippi. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Apr 27, 2015, 7:44 AM CDT (12:44 UTC)
Expired: Apr 27, 2015, 9:15 AM CDT
In force: 91 min
Issued by: the Storm Prediction Center

All 38 counties

Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Jefferson Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Pointe Coupee Parish, LA, Rapides 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, Terrebonne Parish, LA, Vermilion Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Hancock County, MS, Pearl River County, MS, Pike County, MS, Walthall County, MS, Wilkinson County, MS

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 0.7 hours before the alert went out and 175 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: 2462 J/kg
Mixed-layer CIN: -33 J/kg
Mixed-layer LCL: 722 m above ground
0-6 km bulk shear: 61 kt
0-1 km storm-relative helicity: 189 m²/s²
0-3 km storm-relative helicity: 364 m²/s²
Significant tornado parameter: 6.1
Supercell composite: 23.1

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
Apr 27, 1:27 AM CDT	Tornado Watch	SPC	Bossier, Caddo, De Soto, Sabine	6 hr
Apr 27, 4:56 AM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 15 more	2 hr
Apr 27, 6:01 AM CDT	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 36 more	7 hr
Apr 27, 9:47 AM CDT	Mesoscale Discussion	SPC	Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 6 more	88 min
Apr 27, 1:08 PM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 8 more	97 min

Nearby

Mesoscale Discussions in Louisiana, 2015 Mesoscale Discussions in Mississippi, 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.