Alert archive / Louisiana / Mesoscale Discussions in 2004

Mesoscale Discussion 493

April 29, 2004Ashley County, Bradley County, Union County, Arkansas; 14 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Apr 29, 2004, 11:22 AM CDT for Ashley County, Bradley County, Union County, Arkansas; 14 parishes in Louisiana. It was in force for 113 min.

The area

The outline as issued.

The facts

Issued: Apr 29, 2004, 11:22 AM CDT (16:22 UTC)
Expired: Apr 29, 2004, 1:15 PM CDT
In force: 113 min
Issued by: the Storm Prediction Center

Counties Ashley County, AR, Bradley County, AR, Union County, AR, Caldwell Parish, LA, Catahoula Parish, LA, Franklin Parish, LA, Grant Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Richland Parish, LA, Tensas Parish, LA, Union Parish, LA, Vernon Parish, LA, West Carroll Parish, LA

The watches that followed

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

Tornado Watch 124Apr 29, 1:10 PM CDT

The nearest sounding before it

Shreveport, LA (KSHV), launched 12:00Z, 4.4 hours before the alert went out and 136 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1349 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 250 m²/s²
0-3 km storm-relative helicity: 281 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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
Apr 29, 1:10 PM CDT	Tornado Watch	SPC	Ashley, Bradley, Calhoun, Chicot, Drew, Union	6 hr
Apr 29, 2:44 PM CDT	Mesoscale Discussion	SPC	Ashley, Chicot, Drew	2 hr
Apr 29, 5:36 PM CDT	Mesoscale Discussion	SPC	Chicot	84 min
Apr 29, 1:56 PM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, Avoyelles, Concordia, East Baton Rouge, East Feliciana and 23 more	2 hr
Apr 29, 3:15 PM CDT	Tornado Watch	SPC	Plaquemines, Saint Bernard	6 hr
Apr 29, 6:15 PM CDT	Mesoscale Discussion	SPC	Orleans, Saint Bernard, Saint Tammany	90 min

Nearby

Mesoscale Discussions in Louisiana, 2004 Mesoscale Discussions in Arkansas, 2004 Every mesoscale discussion in 2004

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.