Alert archive / Kentucky / Mesoscale Discussions in 2018

Mesoscale Discussion 1098

July 20, 201817 counties in Kentucky; Montgomery County, Robertson County, Stewart County, Tennessee

The Storm Prediction Center issued this mesoscale discussion at Jul 20, 2018, 11:17 AM CDT for 17 counties in Kentucky; Montgomery County, Robertson County, Stewart County, Tennessee. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: Jul 20, 2018, 11:17 AM CDT (16:17 UTC)
Expired: Jul 20, 2018, 12:15 PM CDT
In force: 58 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Butler County, KY, Caldwell County, KY, Calloway County, KY, Christian County, KY, Crittenden County, KY, Daviess County, KY, Hopkins County, KY, Logan County, KY, Lyon County, KY, Marshall County, KY, McLean County, KY, Muhlenberg County, KY, Ohio County, KY, Todd County, KY, Trigg County, KY, Warren County, KY, Webster County, KY, Montgomery County, TN, Robertson County, TN, Stewart County, TN

The radar

The Ft Campbell radar (KHPX), 39 km from the middle of the area, began a volume at 16:17 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.

Tornado Watch 289Jul 20, 12:35 PM CDT

The nearest sounding before it

Nashville Metro, TN (KBNA), launched 12:00Z, 4.3 hours before the alert went out and 129 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: 918 J/kg
Mixed-layer CIN: -46 J/kg
Mixed-layer LCL: 766 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 123 m²/s²
0-3 km storm-relative helicity: 206 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 5.7

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
Jul 20, 12:19 PM CDT	Mesoscale Discussion	SPC	Adair, Anderson, Barren, Boone, Boyle, Breckinridge and 33 more	56 min
Jul 20, 12:37 PM CDT	Tornado Watch	SPC	Adair, Allen, Anderson, Barren, Boone, Bourbon and 54 more	7 hr
Jul 20, 12:58 PM CDT	Mesoscale Discussion	SPC	Ballard, Caldwell, Calloway, Carlisle, Christian, Crittenden and 18 more	62 min
Jul 20, 2:43 PM CDT	Mesoscale Discussion	SPC	Adair, Anderson, Bath, Boone, Bourbon, Boyle and 60 more	62 min
Jul 20, 3:16 PM CDT	Severe Thunderstorm Watch	SPC	Bath, Bell, Boyd, Breathitt, Carter, Clay and 31 more	6 hr
Jul 20, 5:37 PM CDT	Mesoscale Discussion	SPC	Adair, Allen, Anderson, Barren, Boone, Bourbon and 57 more	53 min
Jul 20, 5:54 PM CDT	Mesoscale Discussion	SPC	Allen, Barren, Butler, Caldwell, Calloway, Christian and 17 more	3 hr
Jul 20, 6:22 PM CDT	Tornado Watch	SPC	Adair, Allen, Anderson, Ballard, Barren, Bourbon and 65 more	8 hr
Jul 20, 6:24 PM CDT	Mesoscale Discussion	SPC	Bath, Bell, Boyd, Breathitt, Carter, Clark and 33 more	96 min
Jul 19, 8:54 PM CDT	Severe Thunderstorm Watch	SPC	Dyer, Fayette, Haywood, Lauderdale, Shelby, Tipton	114 min

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.