Alert archive / Alabama / Mesoscale Discussions in 2020

Mesoscale Discussion 356

April 12, 202039 counties in Alabama; 5 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Apr 12, 2020, 1:45 PM CDT for 39 counties in Alabama; 5 counties in Tennessee. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: Apr 12, 2020, 1:45 PM CDT (18:45 UTC)
Expired: Apr 12, 2020, 3:15 PM CDT
In force: 90 min
Issued by: the Storm Prediction Center
Chance of a watch: 95%

All 44 counties

Autauga County, AL, Bibb County, AL, Blount County, AL, Calhoun County, AL, Cherokee County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Colbert County, AL, Coosa County, AL, Cullman County, AL, Dallas County, AL, DeKalb County, AL, Etowah County, AL, Fayette County, AL, Franklin County, AL, Greene County, AL, Hale County, AL, Jackson County, AL, Jefferson County, AL, Lamar County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marengo County, AL, Marion County, AL, Marshall County, AL, Morgan County, AL, Perry County, AL, Pickens County, AL, Randolph County, AL, Shelby County, AL, St. Clair County, AL, Sumter County, AL, Talladega County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL, Franklin County, TN, Giles County, TN, Lawrence County, TN, Lincoln County, TN, Wayne County, TN

The radar

The Birmingham radar (KBMX), 96 km from the middle of the area, began a volume at 18:47 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, 6.8 hours before the alert went out and 95 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: 1885 m above ground
0-6 km bulk shear: 61 kt
0-1 km storm-relative helicity: 336 m²/s²
0-3 km storm-relative helicity: 578 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 12, 3:20 PM CDT	Tornado Watch	SPC	Bibb, Blount, Calhoun, Cherokee, Chilton, Clay and 30 more	8 hr
Apr 12, 3:38 PM CDT	Mesoscale Discussion	SPC	Fayette, Greene, Lamar, Pickens, Sumter, Tuscaloosa and 1 more	97 min
Apr 12, 3:53 PM CDT	Mesoscale Discussion	SPC	Clarke, Washington	97 min
Apr 12, 4:38 PM CDT	Tornado Watch PDS	SPC	Autauga, Baldwin, Bibb, Calhoun, Chilton, Choctaw and 22 more	7 hr
Apr 12, 4:54 PM CDT	Mesoscale Discussion	SPC	Choctaw	66 min
Apr 12, 5:14 PM CDT	Mesoscale Discussion	SPC	Blount, Calhoun, Cherokee, Cleburne, Cullman, DeKalb and 13 more	91 min
Apr 12, 5:44 PM CDT	Mesoscale Discussion	SPC	Lamar, Marion	91 min

Nearby

Mesoscale Discussions in Alabama, 2020 Mesoscale Discussions in Tennessee, 2020 Every mesoscale discussion in 2020

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.