Alert archive / Kentucky / Mesoscale Discussions in 2017

Mesoscale Discussion 583

April 28, 20174 states

The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2017, 11:19 PM EDT for 4 states. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued: Apr 28, 2017, 11:19 PM EDT (03:19 UTC)
Expired: Apr 29, 2017, 1:15 AM EDT
In force: 116 min
Issued by: the Storm Prediction Center

All 79 counties

Clark County, IN, Crawford County, IN, Daviess County, IN, Dearborn County, IN, Dubois County, IN, Floyd County, IN, Gibson 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, Pike County, IN, Ripley County, IN, Scott County, IN, Spencer County, IN, Switzerland County, IN, Vanderburgh County, IN, Warrick County, IN, Washington County, IN, Boone County, KY, Boyd County, KY, Bracken County, KY, Campbell County, KY, Carroll County, KY, Carter County, KY, Fleming County, KY, Franklin County, KY, Gallatin County, KY, Grant County, KY, Greenup County, KY, Harrison County, KY, Henry County, KY, Jefferson County, KY, Kenton County, KY, Lewis County, KY, Mason County, KY, Nicholas County, KY, Oldham County, KY, Owen County, KY, Pendleton County, KY, Robertson County, KY, Scott County, KY, Shelby County, KY, Trimble County, KY, Adams County, OH, Athens County, OH, Brown County, OH, Clermont County, OH, Clinton County, OH, Gallia County, OH, Hamilton County, OH, Highland County, OH, Hocking County, OH, Jackson County, OH, Lawrence County, OH, Meigs County, OH, Pike County, OH, Ross County, OH, Scioto County, OH, Vinton County, OH, Warren County, OH, Braxton County, WV, Cabell County, WV, Calhoun County, WV, Clay County, WV, Gilmer County, WV, Jackson County, WV, Lewis County, WV, Mason County, WV, Putnam County, WV, Ritchie County, WV, Roane County, WV, Wirt County, WV, Wood County, WV

The radar

The Louisville radar (KLVX), 119 km from the middle of the area, began a volume at 03:20 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

Cncnati-Daytn, OH (KILN), launched 00:00Z, 3.3 hours before the alert went out and 128 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1645 m above ground
0-6 km bulk shear: 76 kt
0-1 km storm-relative helicity: 419 m²/s²
0-3 km storm-relative helicity: 848 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

620 
ACUS11 KWNS 290319
SWOMCD
SPC MCD 290319 
WVZ000-OHZ000-KYZ000-INZ000-290515-

Mesoscale Discussion 0583
NWS Storm Prediction Center Norman OK
1019 PM CDT Fri Apr 28 2017

Areas affected...Parts of southern Indiana...northern
Kentucky...southern Ohio...northern West Virginia

Concerning...Tornado Watch 171...

Valid 290319Z - 290515Z

The severe weather threat for Tornado Watch 171 continues.

SUMMARY...Severe weather potential is expected to linger across
severe thunderstorm watch 170 and tornado watch 171 at least into
the 1-2 am EDT time frame.  The need for an additional watch farther
east into the central Appalachians is not currently anticipated, but
trends will be monitored.

DISCUSSION...Vigorous thunderstorm activity continues to form within
a relatively narrow zone focused near or just to the cool side of a
quasi-stationary frontal zone across the lower Ohio Valley, near the
river, into the central Appalachians.  This is occurring beneath an
axis of 60-90 meter 500 mb height rises, which may be tending to
suppress convection at least somewhat.  However, the environment
appears characterized by sizable CAPE on the order of 1000-2000 J/kg
(diminishing in magnitude from west to east), in the presence of
40-50 kt west southwesterly lower/mid tropospheric flow.  

This may continue to be conducive to organizing storm structures,
including supercells, accompanied by a risk for potentially damaging
wind gusts and some hail.  A somewhat more moist, potentially
unstable boundary layer near the front across parts of southern
Indiana and adjacent portions of north central Kentucky, may still
support potential for an isolated tornado or two.  Severe weather
potential with storms spreading east of the Ohio River into less
unstable environment across northern West Virginia may not be
completely negligible, but probably is less than that that exists to
the west.

..Kerr.. 04/29/2017

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

ATTN...WFO...RLX...JKL...ILN...LMK...IND...PAH...

LAT...LON   38528756 38888705 39428452 39668250 39148034 38408098
            38308332 38188531 38028658 37898782 38528756

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 28, 8:10 PM EDT	Severe Thunderstorm Watch	SPC	Bartholomew, Brown, Dearborn, Decatur, Fayette, Franklin and 8 more	6 hr
Apr 28, 9:27 PM EDT	Tornado Watch	SPC	Clark, Crawford, Dubois, Floyd, Gibson, Harrison and 10 more	5 hr
Apr 29, 1:50 AM EDT	Mesoscale Discussion	SPC	Clark, Crawford, Dubois, Floyd, Gibson, Harrison and 11 more	85 min
Apr 29, 7:23 AM EDT	Mesoscale Discussion	SPC	Clark, Dearborn, Floyd, Harrison, Jackson, Jefferson and 6 more	3 hr
Apr 29, 4:28 PM EDT	Mesoscale Discussion	SPC	Daviess, Gibson, Greene, Knox, Pike, Posey and 3 more	2 hr
Apr 29, 7:30 PM EDT	Mesoscale Discussion	SPC	Bartholomew, Brown, Clay, Daviess, Dubois, Gibson and 23 more	60 min
Apr 29, 12:55 AM EDT	Mesoscale Discussion	SPC	Ballard, Carlisle, Crittenden, Fulton, Graves, Hickman and 4 more	95 min
Apr 29, 4:57 PM EDT	Severe Thunderstorm Watch	SPC	Ballard, McCracken	6 hr

Nearby

Mesoscale Discussions in Kentucky, 2017 Mesoscale Discussions in Indiana, 2017 Mesoscale Discussions in Ohio, 2017 Every 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.