Alert archive / Louisiana / Mesoscale Discussions in 2015

Mesoscale Discussion 778

May 25, 201528 parishes in Louisiana; 10 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at May 25, 2015, 10:14 PM CDT for 28 parishes in Louisiana; 10 counties in Mississippi. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: May 25, 2015, 10:14 PM CDT (03:14 UTC)
Expired: May 25, 2015, 11:45 PM CDT
In force: 91 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 38 counties

Acadia Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Franklin Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Lafayette Parish, LA, Livingston Parish, LA, Madison Parish, LA, Pointe Coupee Parish, LA, Richland 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, St. Mary Parish, LA, Tensas Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Copiah County, MS, Franklin County, MS, Issaquena County, MS, Jefferson County, MS, Lincoln County, MS, Warren County, MS, Wilkinson County, MS

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Tornado Watch 219May 25, 10:35 PM CDT

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 3.2 hours before the alert went out and 162 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: 693 J/kg
Mixed-layer CIN: -75 J/kg
Mixed-layer LCL: 967 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 37 m²/s²
0-3 km storm-relative helicity: 77 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.9

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
May 25, 8:05 PM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Beauregard, Bienville, Bossier, Caddo and 17 more	85 min
May 25, 10:37 PM CDT	Tornado Watch	SPC	Ascension, Assumption, Avoyelles, Catahoula, Concordia, East Baton Rouge and 32 more	6 hr
May 25, 11:13 PM CDT	Mesoscale Discussion	SPC	Allen, Beauregard, Calcasieu, Cameron, Evangeline, Jefferson Davis and 1 more	92 min
May 25, 11:57 PM CDT	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Avoyelles, Concordia, East Baton Rouge and 27 more	93 min
May 26, 3:50 AM CDT	Mesoscale Discussion	SPC	Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 4 more	85 min
May 26, 6:22 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Caldwell, Catahoula, Claiborne and 15 more	83 min
May 25, 8:52 PM CDT	Mesoscale Discussion	SPC	Bolivar, Coahoma, DeSoto, Quitman, Tate, Tunica	83 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.