Alert archive / Louisiana / Mesoscale Discussions in 2009

Mesoscale Discussion 671

May 2, 200925 parishes in Louisiana; Adams County, Mississippi; 16 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 2, 2009, 3:04 PM CDT for 25 parishes in Louisiana; Adams County, Mississippi; 16 counties in Texas. It was in force for 26 min.

The area

The outline as issued.

The facts

Issued: May 2, 2009, 3:04 PM CDT (20:04 UTC)
Expired: May 2, 2009, 3:30 PM CDT
In force: 26 min
Issued by: the Storm Prediction Center

All 42 counties

Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Claiborne Parish, LA, Concordia Parish, LA, De Soto Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Tensas Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Adams County, MS, Anderson County, TX, Camp County, TX, Cherokee County, TX, Gregg County, TX, Harrison County, TX, Houston County, TX, Marion County, TX, Nacogdoches County, TX, Panola County, TX, Rusk County, TX, Sabine County, TX, San Augustine County, TX, Shelby County, TX, Smith County, TX, Upshur County, TX, Wood County, TX

The radar

The Shreveport radar (KSHV), 16 km from the middle of the area, began a volume at 20:06 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 228May 2, 6:05 PM CDT

The nearest sounding before it

Shreveport, LA (KSHV), launched 12:00Z, 8.1 hours before the alert went out and 23 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: 1211 J/kg
Mixed-layer CIN: -39 J/kg
Mixed-layer LCL: 501 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 134 m²/s²
0-3 km storm-relative helicity: 172 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.4

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 2, 5:10 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 12 more	65 min
May 2, 6:03 PM CDT	Tornado Watch	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, East Carroll and 10 more	6 hr
May 2, 1:45 AM CDT	Mesoscale Discussion	SPC	Benton, Bolivar, Calhoun, Coahoma, DeSoto, Grenada and 12 more	90 min
May 2, 9:23 AM CDT	Mesoscale Discussion	SPC	Bolivar, Coahoma, Washington	97 min
May 2, 2:38 PM CDT	Mesoscale Discussion	SPC	Alcorn, Benton, Bolivar, Calhoun, Carroll, Chickasaw and 27 more	97 min
May 2, 2:55 PM CDT	Tornado Watch	SPC	Attala, Bolivar, Calhoun, Carroll, Chickasaw, Choctaw and 26 more	6 hr
May 2, 5:22 PM CDT	Mesoscale Discussion	SPC	Attala, Bolivar, Calhoun, Carroll, Chickasaw, Choctaw and 27 more	53 min
May 1, 7:19 PM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Childress, Clay, Cooke, Cottle and 21 more	86 min
May 1, 9:36 PM CDT	Mesoscale Discussion	SPC	Fannin, Lamar	84 min
May 2, 2:58 AM CDT	Mesoscale Discussion	SPC	Collingsworth, Gray, Hemphill, Wheeler	3 hr
May 2, 12:17 PM CDT	Tornado Watch	SPC	Bowie, Camp, Cass, Collin, Delta, Denton and 15 more	7 hr
May 2, 1:24 PM CDT	Mesoscale Discussion	SPC	Bell, Blanco, Bosque, Burnet, Collin, Coryell and 31 more	66 min
May 2, 1:56 PM CDT	Tornado Watch	SPC	Bell, Bosque, Coryell, Dallas, Ellis, Falls and 18 more	4 hr
May 2, 3:47 PM CDT	Mesoscale Discussion	SPC	Bowie, Camp, Cass, Dallas, Delta, Franklin and 12 more	58 min
May 2, 5:25 PM CDT	Mesoscale Discussion	SPC	Bowie	95 min
May 2, 6:49 PM CDT	Mesoscale Discussion	SPC	Camp, Cass, Franklin, Hopkins, Hunt, Kaufman and 7 more	86 min

Nearby

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