Alert archive / Alabama / Mesoscale Discussions in 2018

Mesoscale Discussion 847

June 23, 201815 counties in Alabama; 4 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Jun 23, 2018, 8:23 PM CDT for 15 counties in Alabama; 4 counties in Tennessee. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jun 23, 2018, 8:23 PM CDT (01:23 UTC)
Expired: Jun 23, 2018, 10:30 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Blount County, AL, Colbert County, AL, Cullman County, AL, Fayette County, AL, Franklin County, AL, Lamar County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marion County, AL, Marshall County, AL, Morgan County, AL, Walker County, AL, Winston County, AL, Giles County, TN, Lawrence County, TN, Lincoln County, TN, Wayne County, TN

The radar

The Columbus AFB radar (KGWX), 111 km from the middle of the area, began a volume at 01:24 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, 1.4 hours before the alert went out and 163 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: 2111 J/kg
Mixed-layer CIN: -25 J/kg
Mixed-layer LCL: 953 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 74 m²/s²
0-3 km storm-relative helicity: 135 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 3.4

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
Jun 24, 2:33 AM CDT	Mesoscale Discussion	SPC	Chester, Fayette, Hardeman, Haywood, Lauderdale, McNairy and 3 more	87 min
Jun 24, 4:53 PM CDT	Mesoscale Discussion	SPC	Blount, Loudon, Monroe	97 min
Jun 24, 6:39 PM CDT	Mesoscale Discussion	SPC	Benton, Carroll, Crockett, Dickson, Dyer, Gibson and 13 more	2 hr

Nearby

Mesoscale Discussions in Alabama, 2018 Mesoscale Discussions in Tennessee, 2018 Every mesoscale discussion in 2018

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.