Alert archive / Kentucky / Mesoscale Discussions in 2017

Mesoscale Discussion 803

May 20, 20174 states

The Storm Prediction Center issued this mesoscale discussion at May 20, 2017, 6:42 PM EDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
May 20, 2017, 6:42 PM EDT (22:42 UTC)
Expired
May 20, 2017, 8:45 PM EDT
In force
2 hr
Issued by
the Storm Prediction Center
All 80 counties

Bartholomew County, IN, Brown County, IN, Clark County, IN, Crawford County, IN, Dearborn County, IN, Decatur County, IN, Dubois County, IN, Fayette County, IN, Floyd County, IN, Franklin County, IN, Harrison County, IN, Jackson County, IN, Jefferson County, IN, Jennings County, IN, Lawrence County, IN, Martin County, IN, Ohio County, IN, Orange County, IN, Perry County, IN, Ripley County, IN, Rush County, IN, Scott County, IN, Shelby County, IN, Spencer County, IN, Switzerland County, IN, Union County, IN, Warrick County, IN, Washington County, IN, Boone County, KY, Breckinridge County, KY, Bullitt County, KY, Butler County, KY, Caldwell County, KY, Calloway County, KY, Campbell County, KY, Carroll County, KY, Christian County, KY, Daviess County, KY, Edmonson County, KY, Franklin County, KY, Gallatin County, KY, Grant County, KY, Grayson County, KY, Hancock County, KY, Hardin County, KY, Hart County, KY, Henderson County, KY, Henry County, KY, Hopkins County, KY, Jefferson County, KY, Kenton County, KY, Larue County, KY, Logan County, KY, Lyon County, KY, McLean County, KY, Meade County, KY, Muhlenberg County, KY, Nelson County, KY, Ohio County, KY, Oldham County, KY, Owen County, KY, Shelby County, KY, Simpson County, KY, Spencer County, KY, Todd County, KY, Trigg County, KY, Trimble County, KY, Warren County, KY, Webster County, KY, Butler County, OH, Clermont County, OH, Hamilton County, OH, Cheatham County, TN, Dickson County, TN, Henry County, TN, Houston County, TN, Humphreys County, TN, Montgomery County, TN, Robertson County, TN, Stewart County, TN

The radar

The Louisville radar (KLVX), 70 km from the middle of the area, began a volume at 22:45 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, 10.7 hours before the alert went out and 174 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-pSkew-T log-p diagram, Nashville Metro, TN at 12:00Z on 2017-05-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 268 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Nashville Metro, TN at 12:00Z on 2017-05-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 23 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
268 J/kg
Mixed-layer CIN
-127 J/kg
Mixed-layer LCL
1494 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
23 m²/s²
0-3 km storm-relative helicity
18 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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.

IssuedProductOfficeCountiesLasted
May 20, 12:13 PM EDTMesoscale DiscussionSPCBartholomew, Brown, Clark, Crawford, Dearborn, Decatur and 22 more92 min
May 20, 4:23 PM EDTSevere Thunderstorm WatchSPCClark, Crawford, Floyd, Harrison, Jefferson, Orange and 3 more7 hr
May 20, 7:07 PM EDTMesoscale DiscussionSPCAdams, Benton, Blackford, Boone, Carroll, Cass and 31 more2 hr
May 19, 10:18 PM EDTMesoscale DiscussionSPCBreathitt, Clay, Floyd, Jackson, Johnson, Knott and 16 more87 min
May 20, 2:45 AM EDTMesoscale DiscussionSPCBallard90 min

Nearby

Mesoscale Discussions in Kentucky, 2017Mesoscale Discussions in Indiana, 2017Mesoscale Discussions in Tennessee, 2017Every mesoscale discussion in 2017

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.