Alert archive / Alabama / Mesoscale Discussions in 2020

Mesoscale Discussion 371

April 12, 20208 counties in Alabama

The Storm Prediction Center issued this mesoscale discussion at Apr 12, 2020, 8:50 PM CDT for 8 counties in Alabama. It was in force for 55 min.

The area

The outline as issued.

The facts

Issued: Apr 12, 2020, 8:50 PM CDT (01:50 UTC)
Expired: Apr 12, 2020, 9:45 PM CDT
In force: 55 min
Issued by: the Storm Prediction Center

Counties Blount County, AL, Cullman County, AL, Etowah County, AL, Jefferson County, AL, Shelby County, AL, St. Clair County, AL, Tuscaloosa County, AL, Walker County, AL

The radar

The Birmingham radar (KBMX), 49 km from the middle of the area, began a volume at 01:50 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

Birmingham, AL (KBMX), launched 00:00Z, 1.8 hours before the alert went out and 48 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: 533 J/kg
Mixed-layer CIN: -55 J/kg
Mixed-layer LCL: 847 m above ground
0-6 km bulk shear: 63 kt
0-1 km storm-relative helicity: 401 m²/s²
0-3 km storm-relative helicity: 509 m²/s²
Significant tornado parameter: 1.4
Supercell composite: 8.4

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, 7:36 PM CDT	Mesoscale Discussion	SPC	Autauga, Bibb, Blount, Calhoun, Chilton, Choctaw and 16 more	84 min
Apr 12, 10:28 PM CDT	Mesoscale Discussion	SPC	Autauga, Baldwin, Barbour, Bullock, Butler, Calhoun and 32 more	92 min
Apr 12, 10:45 PM CDT	Tornado Watch	SPC	Autauga, Baldwin, Barbour, Bullock, Butler, Calhoun and 26 more	8 hr
Apr 12, 11:19 PM CDT	Mesoscale Discussion	SPC	Colbert, Franklin, Lamar, Lauderdale, Lawrence, Marion	86 min

Nearby

Mesoscale Discussions in Alabama, 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.