Alert archive / Louisiana / Mesoscale Discussions in 2016

Mesoscale Discussion 516

April 30, 20164 states

The Storm Prediction Center issued this mesoscale discussion at Apr 30, 2016, 4:00 PM CDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 30, 2016, 4:00 PM CDT (21:00 UTC)
Expired: Apr 30, 2016, 6:00 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 33 counties

Baldwin County, AL, Mobile County, AL, Escambia County, FL, Santa Rosa County, FL, Ascension Parish, LA, Assumption Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines 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 Tammany Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Washington Parish, LA, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Lamar County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Stone County, MS, Walthall County, MS

The radar

The Mobile radar (KMOB), 126 km from the middle of the area, began a volume at 21:00 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

Slidell Radar S, LA (KSIL), launched 12:00Z, 9.0 hours before the alert went out and 61 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: 1180 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 565 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 114 m²/s²
0-3 km storm-relative helicity: 97 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 3.9

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 30, 4:51 PM CDT	Mesoscale Discussion	SPC	Jackson, Limestone, Madison	54 min
Apr 29, 8:56 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 8 more	94 min
Apr 29, 9:58 PM CDT	Severe Thunderstorm Watch	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 8 more	7 hr
Apr 29, 11:42 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 5 more	93 min
Apr 30, 3:23 AM CDT	Mesoscale Discussion	SPC	Beauregard, Bienville, Bossier, Claiborne, De Soto, Lincoln and 5 more	97 min
Apr 30, 5:11 AM CDT	Severe Thunderstorm Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Bienville, Calcasieu and 22 more	9 hr
Apr 30, 7:38 AM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 2 more	67 min
Apr 30, 10:22 AM CDT	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Calcasieu, Cameron, East Baton Rouge and 16 more	53 min
Apr 30, 11:38 AM CDT	Severe Thunderstorm Watch	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberville, Jefferson and 16 more	7 hr
Apr 30, 1:35 PM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 22 more	55 min

Nearby

Mesoscale Discussions in Louisiana, 2016 Mesoscale Discussions in Mississippi, 2016 Mesoscale Discussions in Alabama, 2016 Every mesoscale discussion in 2016

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.