Alert archive / Alabama / Mesoscale Discussions in 2013

Mesoscale Discussion 1902

September 21, 201330 counties in Alabama; Saint Tammany Parish, Washington Parish, Louisiana; 16 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Sep 21, 2013, 4:35 AM CDT for 30 counties in Alabama; Saint Tammany Parish, Washington Parish, Louisiana; 16 counties in Mississippi. It was in force for 85 min.

The area

The outline as issued.

The facts

Issued: Sep 21, 2013, 4:35 AM CDT (09:35 UTC)
Expired: Sep 21, 2013, 6:00 AM CDT
In force: 85 min
Issued by: the Storm Prediction Center
Chance of a watch: 5%

All 48 counties

Autauga County, AL, Bibb County, AL, Butler County, AL, Chilton County, AL, Choctaw County, AL, Clarke County, AL, Conecuh County, AL, Coosa County, AL, Covington County, AL, Crenshaw County, AL, Dallas County, AL, Elmore County, AL, Escambia County, AL, Greene County, AL, Hale County, AL, Jefferson County, AL, Lowndes County, AL, Marengo County, AL, Monroe County, AL, Montgomery County, AL, Perry County, AL, Pickens County, AL, Shelby County, AL, St. Clair County, AL, Sumter County, AL, Talladega County, AL, Tuscaloosa County, AL, Walker County, AL, Washington County, AL, Wilcox County, AL, Saint Tammany Parish, LA, Washington Parish, LA, Clarke County, MS, Covington County, MS, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Jasper County, MS, Jones County, MS, Kemper County, MS, Lamar County, MS, Lauderdale County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Stone County, MS, Wayne County, MS

The radar

The Birmingham radar (KBMX), 134 km from the middle of the area, began a volume at 09:37 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

Jackson, MS (KJAN), launched 00:00Z, 9.6 hours before the alert went out and 221 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: 375 J/kg
Mixed-layer CIN: -41 J/kg
Mixed-layer LCL: 638 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: 33 m²/s²
0-3 km storm-relative helicity: 77 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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Nearby

Mesoscale Discussions in Alabama, 2013 Mesoscale Discussions in Mississippi, 2013 Mesoscale Discussions in Louisiana, 2013 Every mesoscale discussion in 2013

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.