Alert archive / Louisiana / Mesoscale Discussions in 2011

Mesoscale Discussion 2112

September 3, 20114 states

The Storm Prediction Center issued this mesoscale discussion at Sep 3, 2011, 5:57 PM CDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Sep 3, 2011, 5:57 PM CDT (22:57 UTC)
Expired: Sep 3, 2011, 8:00 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 63 counties

Baldwin County, AL, Escambia County, AL, Mobile County, AL, Washington County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Jefferson Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Pointe Coupee 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 Landry Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson 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.

Tornado Watch 830Sep 3, 9:45 PM CDT

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 11.0 hours before the alert went out and 39 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: 850 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 477 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 286 m²/s²
0-3 km storm-relative helicity: 260 m²/s²
Significant tornado parameter: 1.0
Supercell composite: 7.0

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
Sep 3, 1:43 AM CDT	Tornado Watch	SPC	Baldwin, Mobile	8 hr
Sep 3, 7:46 AM CDT	Mesoscale Discussion	SPC	Baldwin, Escambia, Mobile	119 min
Sep 3, 9:41 AM CDT	Tornado Watch	SPC	Baldwin, Mobile	12 hr
Sep 3, 1:41 PM CDT	Mesoscale Discussion	SPC	Baldwin, Conecuh, Covington, Escambia, Mobile, Washington	64 min
Sep 2, 11:32 PM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, Iberia, Iberville, Jefferson and 15 more	118 min

Nearby

Mesoscale Discussions in Louisiana, 2011 Mesoscale Discussions in Mississippi, 2011 Mesoscale Discussions in Alabama, 2011 Every mesoscale discussion in 2011

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.