Alert archive / Louisiana / Mesoscale Discussions in 2009

Mesoscale Discussion 286

March 26, 20094 states

The Storm Prediction Center issued this mesoscale discussion at Mar 26, 2009, 11:53 PM CDT for 4 states. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued: Mar 26, 2009, 11:53 PM CDT (04:53 UTC)
Expired: Mar 27, 2009, 1:30 AM CDT
In force: 97 min
Issued by: the Storm Prediction Center

All 22 counties

Baldwin County, AL, Mobile County, AL, Escambia County, FL, Ascension Parish, LA, Assumption Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Saint Charles 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, George County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Pearl River County, MS, Stone County, MS

The radar

The Mobile radar (KMOB), 97 km from the middle of the area, began a volume at 04:56 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 watches that followed

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

Tornado Watch 74Mar 27, 12:50 AM CDT

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 4.9 hours before the alert went out and 52 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: 1797 J/kg
Mixed-layer CIN: -18 J/kg
Mixed-layer LCL: 559 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: 203 m²/s²
0-3 km storm-relative helicity: 245 m²/s²
Significant tornado parameter: 3.0
Supercell composite: 10.8

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 27, 12:48 AM CDT	Tornado Watch	SPC	Baldwin, Choctaw, Clarke, Conecuh, Covington, Escambia and 3 more	7 hr
Mar 27, 2:23 AM CDT	Mesoscale Discussion	SPC	Baldwin, Choctaw, Clarke, Conecuh, Covington, Escambia and 3 more	67 min
Mar 27, 4:37 AM CDT	Mesoscale Discussion	SPC	Coffee, Conecuh, Covington, Escambia, Geneva, Houston	53 min
Mar 27, 5:02 AM CDT	Tornado Watch	SPC	Coffee, Dale, Geneva, Henry, Houston	5 hr
Mar 27, 6:35 AM CDT	Mesoscale Discussion	SPC	Coffee, Covington, Dale, Geneva, Henry, Houston	55 min
Mar 27, 9:51 AM CDT	Mesoscale Discussion	SPC	Franklin, Gadsden, Gulf, Jefferson, Leon, Liberty and 3 more	24 min
Mar 27, 10:05 AM CDT	Tornado Watch	SPC	Dixie, Franklin, Jefferson, Lafayette, Leon, Madison and 2 more	3 hr
Mar 27, 12:11 PM CDT	Mesoscale Discussion	SPC	Alachua, Baker, Bradford, Clay, Columbia, Dixie and 12 more	64 min
Mar 26, 9:13 PM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 16 more	92 min
Mar 27, 12:33 PM CDT	Mesoscale Discussion	SPC	Bossier, Caddo	57 min
Mar 27, 2:34 PM CDT	Mesoscale Discussion	SPC	Allen, Avoyelles, Beauregard, Evangeline, Rapides, Saint Landry and 1 more	56 min
Mar 27, 2:54 PM CDT	Tornado Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, East Baton Rouge and 14 more	6 hr
Mar 27, 4:16 PM CDT	Tornado Watch	SPC	Caldwell, Catahoula, Concordia, Franklin, Grant, LaSalle and 1 more	4 hr
Mar 27, 4:49 PM CDT	Tornado Watch	SPC	Cameron	3 hr
Mar 27, 5:53 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Claiborne, East Carroll, Jackson, Lincoln and 7 more	97 min
Mar 27, 6:18 PM CDT	Mesoscale Discussion	SPC	Livingston, Saint Helena, Saint Tammany, Tangipahoa, Washington	57 min
Mar 27, 6:35 PM CDT	Tornado Watch	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, East Carroll and 13 more	7 hr

Nearby

Mesoscale Discussions in Louisiana, 2009 Mesoscale Discussions in Mississippi, 2009 Mesoscale Discussions in Alabama, 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; radar from the NEXRAD Level II archive.