Alert archive / Louisiana / Mesoscale Discussions in 2009

Mesoscale Discussion 345

March 31, 200925 parishes in Louisiana; 19 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Mar 31, 2009, 8:58 AM CDT for 25 parishes in Louisiana; 19 counties in Mississippi. It was in force for 92 min.

The area

The outline as issued.

The facts

Issued: Mar 31, 2009, 8:58 AM CDT (13:58 UTC)
Expired: Mar 31, 2009, 10:30 AM CDT
In force: 92 min
Issued by: the Storm Prediction Center

All 44 counties

Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Avoyelles Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Iberville Parish, LA, Lafayette Parish, LA, LaSalle Parish, LA, Livingston Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Helena Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Vernon Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, Jefferson 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, Wilkinson County, MS

The watches that followed

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

Severe Thunderstorm Watch 97Mar 31, 9:35 AM CDT

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 2.0 hours before the alert went out and 181 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: 377 J/kg
Mixed-layer CIN: -94 J/kg
Mixed-layer LCL: 522 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: 287 m²/s²
0-3 km storm-relative helicity: 408 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 4.2

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
Mar 31, 9:37 AM CDT	Severe Thunderstorm Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 38 more	7 hr
Mar 31, 11:54 AM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 46 more	96 min
Mar 31, 2:44 PM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 37 more	91 min
Mar 31, 11:32 AM CDT	Mesoscale Discussion	SPC	George, Greene, Jackson	88 min
Mar 31, 1:05 PM CDT	Severe Thunderstorm Watch	SPC	George, Greene, Hancock, Harrison, Jackson, Perry and 2 more	8 hr
Mar 31, 5:12 PM CDT	Mesoscale Discussion	SPC	George, Greene, Jackson, Perry	93 min

Nearby

Mesoscale Discussions in Louisiana, 2009 Mesoscale Discussions in Mississippi, 2009 Every mesoscale discussion in 2009

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.