Alert archive / Texas / Mesoscale Discussions in 2007

Mesoscale Discussion 2244

December 20, 200720 parishes in Louisiana; 35 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Dec 20, 2007, 3:30 AM CST for 20 parishes in Louisiana; 35 counties in Texas. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: Dec 20, 2007, 3:30 AM CST (09:30 UTC)
Expired: Dec 20, 2007, 5:00 AM CST
In force: 90 min
Issued by: the Storm Prediction Center

All 55 counties

Acadia Parish, LA, Allen Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, De Soto Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Jackson Parish, LA, Jefferson Davis Parish, LA, Natchitoches Parish, LA, Rapides Parish, LA, Red River Parish, LA, Sabine Parish, LA, Vernon Parish, LA, Webster Parish, LA, Winn Parish, LA, Angelina County, TX, Brazoria County, TX, Camp County, TX, Cass County, TX, Chambers County, TX, Cherokee County, TX, Fort Bend County, TX, Galveston County, TX, Gregg County, TX, Hardin County, TX, Harris County, TX, Harrison County, TX, Houston County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Marion County, TX, Montgomery County, TX, Morris County, TX, Nacogdoches County, TX, Newton County, TX, Orange County, TX, Panola County, TX, Polk County, TX, Rusk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Trinity County, TX, Tyler County, TX, Upshur County, TX, Walker County, TX, Waller County, TX, Wharton County, TX

The radar

The Houston radar (KHGX), 107 km from the middle of the area, began a volume at 09:33 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 nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 9.5 hours before the alert went out and 135 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: 276 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 821 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 95 m²/s²
0-3 km storm-relative helicity: 162 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.9

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
Dec 19, 10:12 PM CST	Mesoscale Discussion	SPC	Allen, Beauregard, Calcasieu, Sabine, Vernon	93 min
Dec 20, 8:48 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Avoyelles, Beauregard, Calcasieu and 19 more	57 min
Dec 20, 9:15 AM CST	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 30 more	7 hr
Dec 20, 11:21 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 30 more	84 min
Dec 20, 1:06 PM CST	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 21 more	84 min

Nearby

Mesoscale Discussions in Texas, 2007 Mesoscale Discussions in Louisiana, 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; radar from the NEXRAD Level II archive.