Alert archive / Tennessee / Mesoscale Discussions in 2018

Mesoscale Discussion 217

April 3, 20185 states

The Storm Prediction Center issued this mesoscale discussion at Apr 3, 2018, 11:49 PM EDT for 5 states. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued: Apr 3, 2018, 11:49 PM EDT (03:49 UTC)
Expired: Apr 4, 2018, 1:15 AM EDT
In force: 86 min
Issued by: the Storm Prediction Center

All 56 counties

Catoosa County, GA, Bell County, KY, Floyd County, KY, Harlan County, KY, Knott County, KY, Knox County, KY, Leslie County, KY, Letcher County, KY, Martin County, KY, Perry County, KY, Pike County, KY, Anderson County, TN, Bledsoe County, TN, Blount County, TN, Bradley County, TN, Campbell County, TN, Claiborne County, TN, Cumberland County, TN, Franklin County, TN, Grainger County, TN, Grundy County, TN, Hamblen County, TN, Hamilton County, TN, Hancock County, TN, Hawkins County, TN, Jefferson County, TN, Knox County, TN, Loudon County, TN, Marion County, TN, McMinn County, TN, Meigs County, TN, Monroe County, TN, Morgan County, TN, Polk County, TN, Rhea County, TN, Roane County, TN, Sequatchie County, TN, Union County, TN, Buchanan County, VA, City of Norton, VA, Dickenson County, VA, Lee County, VA, Russell County, VA, Scott County, VA, Wise County, VA, Boone County, WV, Fayette County, WV, Kanawha County, WV, Lincoln County, WV, Logan County, WV, McDowell County, WV, Mingo County, WV, Putnam County, WV, Raleigh County, WV, Wayne County, WV, Wyoming County, WV

The radar

The Knoxville radar (KMRX), 61 km from the middle of the area, began a volume at 03:49 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

Nashville Metro, TN (KBNA), launched 00:00Z, 3.8 hours before the alert went out and 278 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: 398 J/kg
Mixed-layer CIN: -16 J/kg
Mixed-layer LCL: 1862 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: 243 m²/s²
0-3 km storm-relative helicity: 349 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 4.8

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 3, 10:47 PM EDT	Severe Thunderstorm Watch	SPC	Bartow, Catoosa, Chattooga, Dade, Floyd, Gordon and 5 more	4 hr
Apr 4, 12:09 AM EDT	Mesoscale Discussion	SPC	Bartow, Carroll, Catoosa, Chattooga, Cherokee, Cobb and 16 more	66 min
Apr 4, 2:00 AM EDT	Mesoscale Discussion	SPC	Bartow, Carroll, Cherokee, Clayton, Cobb, Coweta and 26 more	105 min
Apr 3, 9:16 PM EDT	Mesoscale Discussion	SPC	Bell, Boyd, Breathitt, Carter, Clay, Elliott and 26 more	89 min
Apr 3, 9:50 PM EDT	Severe Thunderstorm Watch	SPC	Bath, Bell, Breathitt, Clay, Elliott, Estill and 27 more	5 hr
Apr 3, 8:14 PM EDT	Severe Thunderstorm Watch	SPC	Bedford, Benton, Cannon, Carroll, Cheatham, Chester and 45 more	5 hr
Apr 4, 1:27 PM EDT	Mesoscale Discussion	SPC	Accomack, Charles City, Dinwiddie, Essex, Gloucester, Greensville and 32 more	3 hr

Nearby

Mesoscale Discussions in Tennessee, 2018 Mesoscale Discussions in West Virginia, 2018 Mesoscale Discussions in Kentucky, 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.