Alert archive / Louisiana / Mesoscale Discussions in 2009

Mesoscale Discussion 6

January 3, 200915 parishes in Louisiana; 6 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Jan 3, 2009, 4:27 PM CST for 15 parishes in Louisiana; 6 counties in Mississippi. It was in force for 33 min.

The area

The outline as issued.

The facts

Issued: Jan 3, 2009, 4:27 PM CST (22:27 UTC)
Expired: Jan 3, 2009, 5:00 PM CST
In force: 33 min
Issued by: the Storm Prediction Center

All 21 counties

Avoyelles Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Richland Parish, LA, Tensas Parish, LA, Winn Parish, LA, Adams County, MS, Claiborne County, MS, Franklin County, MS, Jefferson County, MS, Warren County, MS, Wilkinson County, MS

The watches that followed

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

Severe Thunderstorm Watch 2Jan 3, 4:30 PM CST

The nearest sounding before it

Shreveport, LA (KSHV), launched 12:00Z, 10.5 hours before the alert went out and 180 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: 1311 J/kg
Mixed-layer CIN: -26 J/kg
Mixed-layer LCL: 541 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 302 m²/s²
0-3 km storm-relative helicity: 277 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
Jan 3, 7:32 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Cameron, East Baton Rouge and 26 more	88 min
Jan 3, 9:33 AM CST	Severe Thunderstorm Watch	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 21 more	6 hr
Jan 3, 12:32 PM CST	Mesoscale Discussion	SPC	Ascension, Assumption, Catahoula, Concordia, East Baton Rouge, East Feliciana and 21 more	88 min
Jan 3, 4:29 PM CST	Severe Thunderstorm Watch	SPC	Caldwell, Catahoula, Concordia, East Carroll, Franklin, Grant and 9 more	3 hr

Nearby

Mesoscale Discussions in Louisiana, 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.