Alert archive / Mississippi / Mesoscale Discussions in 2015

Mesoscale Discussion 364

April 18, 2015Choctaw County, Washington County, Alabama; 8 parishes in Louisiana; 24 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2015, 6:17 PM CDT for Choctaw County, Washington County, Alabama; 8 parishes in Louisiana; 24 counties in Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 18, 2015, 6:17 PM CDT (23:17 UTC)
Expired: Apr 18, 2015, 8:45 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 34 counties

Choctaw County, AL, Washington County, AL, Avoyelles Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, Grant Parish, LA, LaSalle Parish, LA, Rapides Parish, LA, Tensas Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Clarke County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, Greene County, MS, Jasper County, MS, Jefferson County, MS, Jefferson Davis County, MS, Jones County, MS, Lamar County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Perry County, MS, Pike County, MS, Simpson County, MS, Smith County, MS, Walthall County, MS, Wayne County, MS, Wilkinson County, MS

The nearest sounding before it

Jackson, MS (KJAN), launched 12:00Z, 11.3 hours before the alert went out and 128 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 654 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 42 m²/s²
0-3 km storm-relative helicity: 43 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 17, 9:13 PM CDT	Severe Thunderstorm Watch	SPC	Acadia, Calcasieu, Cameron, Iberia, Jefferson Davis, Lafayette and 3 more	5 hr
Apr 17, 11:31 PM CDT	Mesoscale Discussion	SPC	Calcasieu, Cameron, Iberia, Jefferson Davis, Vermilion	59 min
Apr 18, 1:31 AM CDT	Mesoscale Discussion	SPC	Acadia, Assumption, Calcasieu, Cameron, Iberia, Iberville and 5 more	59 min

Nearby

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