Alert archive / Kentucky / Mesoscale Discussions in 2018

Mesoscale Discussion 708

June 11, 201820 counties in Kentucky; 4 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Jun 11, 2018, 5:11 PM EDT for 20 counties in Kentucky; 4 counties in Tennessee. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Jun 11, 2018, 5:11 PM EDT (21:11 UTC)
Expired: Jun 11, 2018, 7:45 PM EDT
In force: 3 hr
Issued by: the Storm Prediction Center
Chance of a watch: 5%

All 24 counties

Bell County, KY, Boyle County, KY, Casey County, KY, Clay County, KY, Garrard County, KY, Harlan County, KY, Jackson County, KY, Knox County, KY, Laurel County, KY, Leslie County, KY, Lincoln County, KY, Marion County, KY, McCreary County, KY, Mercer County, KY, Owsley County, KY, Pulaski County, KY, Rockcastle County, KY, Taylor County, KY, Wayne County, KY, Whitley County, KY, Campbell County, TN, Claiborne County, TN, Grainger County, TN, Union County, TN

The radar

The Jackson,KY radar (KJKL), 113 km from the middle of the area, began a volume at 21:15 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 12:00Z, 9.2 hours before the alert went out and 222 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: 694 J/kg
Mixed-layer CIN: -113 J/kg
Mixed-layer LCL: 1001 m above ground
0-6 km bulk shear: 11 kt
0-1 km storm-relative helicity: 64 m²/s²
0-3 km storm-relative helicity: 50 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

702 
ACUS11 KWNS 112111
SWOMCD
SPC MCD 112111 
VAZ000-TNZ000-KYZ000-112345-

Mesoscale Discussion 0708
NWS Storm Prediction Center Norman OK
0411 PM CDT Mon Jun 11 2018

Areas affected...Central and southeast KY to part of northeast
TN...and far southwest VA

Concerning...Severe potential...Watch unlikely 

Valid 112111Z - 112345Z

Probability of Watch Issuance...5 percent

SUMMARY...Locally, strong damaging wind gusts are possible through
the late afternoon to early evening across southeast Kentucky into
northeast Tennessee and perhaps far southwest Virginia.  WW issuance
is unlikely.

DISCUSSION...Trends in mosaic radar imagery showed a short band of
storms in central KY, extending from Mercer to Marion Counties, and
moving to the east-southeast at 25-30 kt.  Additional isolated
storms had developed along an old outflow boundary which was
analyzed from northeast TN through south-central KY to southern IL. 
The ongoing band of storms in central KY had the strongest forward
motion which should persist as they track along an instability
gradient into southeast KY, northeast TN, and perhaps affecting part
of far southwest VA.  This motion and potential severe wind threat
could be enhanced some, given stronger winds of 35-40 kt observed on
the LVX VWP in the 3-5 km layer.  Spatiotemporal limitations will
preclude the issuance of a severe thunderstorm watch.

..Peters/Hart.. 06/11/2018

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MRX...JKL...LMK...

LAT...LON   37868485 37548385 37148322 36798319 36298336 36168392
            36338426 36718473 37118518 37258543 37368560 37728500
            37868485

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 10, 8:01 PM EDT	Mesoscale Discussion	SPC	Breckinridge, Bullitt, Butler, Crittenden, Daviess, Edmonson and 13 more	59 min
Jun 11, 5:53 PM EDT	Mesoscale Discussion	SPC	Breckinridge, Crittenden, Daviess, Hancock, Henderson, Hopkins and 4 more	2 hr

Nearby

Mesoscale Discussions in Kentucky, 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.