Alert archive / Kentucky / Tornado Watches in 2011

Tornado Watch 163

April 20, 20114 states

The Storm Prediction Center issued this tornado watch at Apr 20, 2011, 1:59 AM EDT for 4 states. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Apr 20, 2011, 1:59 AM EDT (05:59 UTC)
Expired: Apr 20, 2011, 7:17 AM EDT
In force: 5 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1 in
Strongest gust expected: 60 kt

All 89 counties

Bath County, KY, Bell County, KY, Boyd County, KY, Breathitt County, KY, Carter County, KY, Clay County, KY, Elliott County, KY, Estill County, KY, Fleming County, KY, Floyd County, KY, Greenup County, KY, Harlan County, KY, Jackson County, KY, Johnson County, KY, Knott County, KY, Knox County, KY, Laurel County, KY, Lawrence County, KY, Lee County, KY, Leslie County, KY, Letcher County, KY, Magoffin County, KY, Martin County, KY, McCreary County, KY, Menifee County, KY, Montgomery County, KY, Morgan County, KY, Owsley County, KY, Perry County, KY, Pike County, KY, Powell County, KY, Pulaski County, KY, Rockcastle County, KY, Rowan County, KY, Wayne County, KY, Whitley County, KY, Wolfe County, KY, Athens County, OH, Gallia County, OH, Jackson County, OH, Lawrence County, OH, Meigs County, OH, Morgan County, OH, Perry County, OH, Vinton County, OH, Washington County, OH, Buchanan County, VA, City of Bristol, VA, City of Norton, VA, Dickenson County, VA, Lee County, VA, Russell County, VA, Scott County, VA, Washington County, VA, Wise County, VA, Barbour County, WV, Boone County, WV, Braxton County, WV, Cabell County, WV, Calhoun County, WV, Clay County, WV, Doddridge County, WV, Fayette County, WV, Gilmer County, WV, Harrison County, WV, Jackson County, WV, Kanawha County, WV, Lewis County, WV, Lincoln County, WV, Logan County, WV, Mason County, WV, McDowell County, WV, Mingo County, WV, Nicholas County, WV, Pleasants County, WV, Pocahontas County, WV, Putnam County, WV, Raleigh County, WV, Randolph County, WV, Ritchie County, WV, Roane County, WV, Taylor County, WV, Tyler County, WV, Upshur County, WV, Wayne County, WV, Webster County, WV, Wirt County, WV, Wood County, WV, Wyoming County, WV

The radar

The Charleston,WV radar (KRLX), 77 km from the middle of the area, began a volume at 06:02 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 30%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 60%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 10%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 90%

Warnings issued inside it

7 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Apr 20, 2:20 AM EDT	Severe Thunderstorm Warning	JKL	Bath, Fleming, Montgomery, Rowan	25 min
Apr 20, 2:41 AM EDT	Severe Thunderstorm Warning	RLX	Perry	34 min
Apr 20, 2:49 AM EDT	Severe Thunderstorm Warning	JKL	Estill, Lee, Powell, Wolfe	26 min
Apr 20, 2:51 AM EDT	Severe Thunderstorm Warning	RLX	Athens, Jackson, Morgan, Perry, Vinton, Washington	54 min
Apr 20, 3:01 AM EDT	Severe Thunderstorm Warning	JKL	Elliott, Menifee, Morgan, Rowan	44 min
Apr 20, 3:11 AM EDT	Severe Thunderstorm Warning	RLX	Carter, Greenup	64 min
Apr 20, 3:40 AM EDT	Severe Thunderstorm Warning	JKL	McCreary, Pulaski, Wayne	50 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Cncnati-Daytn, OH (KILN), launched 00:00Z, 6.0 hours before the alert went out and 160 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: 1686 J/kg
Mixed-layer CIN: -39 J/kg
Mixed-layer LCL: 1003 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 387 m²/s²
0-3 km storm-relative helicity: 474 m²/s²
Significant tornado parameter: 4.3
Supercell composite: 18.7

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

886 
WWUS20 KWNS 200601
SEL3
SPC WW 200601
KYZ000-OHZ000-VAZ000-WVZ000-201300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 163
NWS STORM PREDICTION CENTER NORMAN OK
200 AM EDT WED APR 20 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

       EASTERN KENTUCKY
       SOUTHEAST OHIO
       SOUTHWEST VIRGINIA
       WEST VIRGINIA

EFFECTIVE THIS WEDNESDAY MORNING FROM 200 AM UNTIL 900 AM EDT.

TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 85 STATUTE
MILES EAST AND WEST OF A LINE FROM 20 MILES EAST NORTHEAST OF
PARKERSBURG WEST VIRGINIA TO 30 MILES SOUTH OF LONDON KENTUCKY.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU3).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 157...WW 159...WW
160...WW 161...WW 162...

DISCUSSION...QLCS WITH EMBEDDED LARGE SCALE LEWP/BOWING STRUCTURE
EXPECTED TO CONTINUE ENE...WITH A CONTINUED THREAT FOR DMGG WIND AND
ISOLD MESOVORTICES/TORNADOES.  RAPID NNEWD SPREAD OF MOISTURE ALONG
70 KT LLJ INTO THE HIGHER TERRAIN OF WV AND ERN KY WILL FURTHER
DESTABILIZE REGION PRIOR TO ARRIVAL OF SQLN.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450.
MEAN STORM MOTION VECTOR 26045.


...CORFIDI

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 19, 9:07 PM EDT	Mesoscale Discussion	SPC	Ballard, Carlisle, Crittenden, Fulton, Graves, Henderson and 5 more	83 min
Apr 19, 9:47 PM EDT	Mesoscale Discussion	SPC	Adair, Anderson, Barren, Boone, Boyle, Bracken and 35 more	88 min
Apr 19, 10:13 PM EDT	Tornado Watch	SPC	Adair, Allen, Anderson, Barren, Boone, Bourbon and 55 more	6 hr
Apr 20, 12:56 AM EDT	Mesoscale Discussion	SPC	Adair, Allen, Anderson, Barren, Bath, Boone and 83 more	94 min
Apr 20, 3:20 AM EDT	Mesoscale Discussion	SPC	Bell, Boyd, Breathitt, Clay, Clinton, Cumberland and 23 more	85 min
Apr 19, 9:37 PM EDT	Severe Thunderstorm Watch	SPC	Allen, Defiance, Fulton, Henry, Paulding, Putnam and 2 more	3 hr
Apr 19, 11:47 PM EDT	Mesoscale Discussion	SPC	Ashland, Carroll, Crawford, Fulton, Hancock, Henry and 14 more	58 min
Apr 20, 12:18 AM EDT	Severe Thunderstorm Watch	SPC	Ashland, Ashtabula, Crawford, Erie, Geauga, Hancock and 21 more	4 hr
Apr 20, 2:22 AM EDT	Severe Thunderstorm Watch	SPC	Belmont, Carroll, Columbiana, Coshocton, Guernsey, Harrison and 5 more	3 hr

Nearby

Tornado Watches in Kentucky, 2011 Tornado Watches in West Virginia, 2011 Tornado Watches in Ohio, 2011 Every tornado watch in 2011

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.