Alert archive / Alabama / Mesoscale Discussions in 2013

Mesoscale Discussion 442

April 11, 201318 counties in Alabama; 4 counties in Mississippi; 9 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Apr 11, 2013, 10:41 AM CDT for 18 counties in Alabama; 4 counties in Mississippi; 9 counties in Tennessee. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 11, 2013, 10:41 AM CDT (15:41 UTC)
Expired: Apr 11, 2013, 12:45 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 31 counties

Colbert County, AL, Cullman County, AL, Fayette County, AL, Franklin County, AL, Greene County, AL, Hale County, AL, Lamar County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marion County, AL, Morgan County, AL, Pickens County, AL, Sumter County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL, Kemper County, MS, Lauderdale County, MS, Lowndes County, MS, Noxubee County, MS, Bedford County, TN, Cannon County, TN, Giles County, TN, Lawrence County, TN, Lincoln County, TN, Marshall County, TN, Maury County, TN, Moore County, TN, Rutherford County, TN

The radar

The Columbus AFB radar (KGWX), 77 km from the middle of the area, began a volume at 15:41 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.

The nearest sounding before it

Birmingham, AL (KBMX), launched 12:00Z, 3.7 hours before the alert went out and 106 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: 35 J/kg
Mixed-layer CIN: -291 J/kg
Mixed-layer LCL: 635 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 143 m²/s²
0-3 km storm-relative helicity: 169 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 11, 11:56 AM CDT	Tornado Watch	SPC	Autauga, Bibb, Blount, Chilton, Colbert, Coosa and 31 more	7 hr
Apr 11, 12:59 PM CDT	Mesoscale Discussion	SPC	Baldwin, Butler, Choctaw, Clarke, Conecuh, Covington and 5 more	91 min
Apr 11, 1:30 PM CDT	Tornado Watch	SPC	Baldwin, Butler, Choctaw, Clarke, Conecuh, Covington and 6 more	8 hr
Apr 11, 2:21 PM CDT	Mesoscale Discussion	SPC	Autauga, Bibb, Blount, Chilton, Coosa, Cullman and 12 more	84 min
Apr 11, 3:26 PM CDT	Mesoscale Discussion	SPC	Chambers, Cleburne, Lee, Randolph, Russell	94 min
Apr 11, 3:45 PM CDT	Tornado Watch	SPC	Barbour, Bullock, Calhoun, Chambers, Cherokee, Clay and 9 more	6 hr
Apr 11, 5:03 PM CDT	Mesoscale Discussion	SPC	Coffee, Dale, Geneva, Henry, Houston	2 hr
Apr 11, 5:35 PM CDT	Mesoscale Discussion	SPC	Baldwin, Butler, Conecuh, Covington, Crenshaw, Escambia and 2 more	115 min
Apr 11, 5:54 PM CDT	Mesoscale Discussion	SPC	Autauga, Bullock, Calhoun, Chambers, Cherokee, Clay and 11 more	96 min
Apr 10, 8:28 PM CDT	Tornado Watch	SPC	Benton, Coahoma, DeSoto, Lafayette, Marshall, Panola and 5 more	7 hr
Apr 10, 9:14 PM CDT	Mesoscale Discussion	SPC	Adams, Claiborne, Holmes, Humphreys, Issaquena, Leflore and 5 more	2 hr
Apr 10, 11:08 PM CDT	Mesoscale Discussion	SPC	DeSoto, Marshall, Panola, Tate, Tunica	97 min
Apr 11, 6:55 AM CDT	Mesoscale Discussion	SPC	Adams, Amite, Claiborne, Copiah, Covington, Forrest and 28 more	65 min
Apr 11, 8:00 AM CDT	Tornado Watch	SPC	Amite, Clarke, Copiah, Covington, Forrest, George and 24 more	8 hr
Apr 11, 12:53 PM CDT	Mesoscale Discussion	SPC	Forrest, George, Greene, Hancock, Harrison, Jackson and 4 more	82 min
Apr 10, 7:55 PM CDT	Mesoscale Discussion	SPC	Dyer, Lake, Lauderdale, Obion, Weakley	95 min
Apr 11, 12:34 PM CDT	Severe Thunderstorm Watch	SPC	Bedford, Cannon, Clay, Coffee, Cumberland, DeKalb and 17 more	6 hr
Apr 11, 2:59 PM CDT	Mesoscale Discussion	SPC	Bedford, Bledsoe, Cannon, Clay, Coffee, Cumberland and 26 more	91 min
Apr 11, 5:06 PM CDT	Mesoscale Discussion	SPC	Anderson, Bledsoe, Blount, Bradley, Campbell, Claiborne and 25 more	84 min
Apr 11, 5:36 PM CDT	Tornado Watch	SPC	Anderson, Bledsoe, Blount, Bradley, Campbell, Carter and 30 more	7 hr

Nearby

Mesoscale Discussions in Alabama, 2013 Mesoscale Discussions in Tennessee, 2013 Mesoscale Discussions in Mississippi, 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.