Alert archive / Louisiana / Mesoscale Discussions in 2007

Mesoscale Discussion 680

May 4, 200723 parishes in Louisiana; 12 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at May 4, 2007, 7:40 AM CDT for 23 parishes in Louisiana; 12 counties in Mississippi. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: May 4, 2007, 7:40 AM CDT (12:40 UTC)
Expired: May 4, 2007, 10:15 AM CDT
In force: 3 hr
Issued by: the Storm Prediction Center

All 35 counties

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, LaSalle Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Franklin County, MS, Hancock County, MS, Jefferson County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Pearl River County, MS, Pike County, MS, Walthall County, MS, Wilkinson County, MS

The nearest sounding before it

Jackson, MS (KJAN), launched 12:00Z, 0.7 hours before the alert went out and 176 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: 93 J/kg
Mixed-layer CIN: -157 J/kg
Mixed-layer LCL: 1036 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 109 m²/s²
0-3 km storm-relative helicity: 171 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

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
May 3, 8:50 PM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 31 more	85 min
May 3, 9:44 PM CDT	Tornado Watch	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 21 more	6 hr
May 3, 11:37 PM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 18 more	83 min
May 4, 1:40 AM CDT	Mesoscale Discussion	SPC	Assumption, Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard and 6 more	65 min
May 4, 11:35 AM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, East Baton Rouge and 27 more	85 min
May 3, 7:55 PM CDT	Mesoscale Discussion	SPC	Bolivar, Carroll, Coahoma, Grenada, Humphreys, Issaquena and 11 more	95 min

Nearby

Mesoscale Discussions in Louisiana, 2007 Mesoscale Discussions in Mississippi, 2007 Every mesoscale discussion in 2007

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.