Alert archive / Kentucky / Tornado Watches in 2011

Tornado Watch 856

September 26, 201122 counties in Kentucky; 8 counties in Ohio

The Storm Prediction Center issued this tornado watch at Sep 26, 2011, 6:43 AM EDT for 22 counties in Kentucky; 8 counties in Ohio. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Sep 26, 2011, 6:43 AM EDT (10:43 UTC)
Expired: Sep 26, 2011, 10:08 AM EDT
In force: 3 hr
Issued by: the Storm Prediction Center
Largest hail expected: 0.5 in
Strongest gust expected: 60 kt

All 30 counties

Bourbon County, KY, Boyle County, KY, Bracken County, KY, Campbell County, KY, Casey County, KY, Clark County, KY, Clinton County, KY, Fayette County, KY, Garrard County, KY, Harrison County, KY, Jessamine County, KY, Lewis County, KY, Lincoln County, KY, Madison County, KY, Mason County, KY, Mercer County, KY, Nicholas County, KY, Pendleton County, KY, Robertson County, KY, Russell County, KY, Scott County, KY, Woodford County, KY, Adams County, OH, Brown County, OH, Clermont County, OH, Clinton County, OH, Highland County, OH, Pike County, OH, Ross County, OH, Scioto County, OH

The radar

The Jackson,KY radar (KJKL), 104 km from the middle of the area, began a volume at 10:44 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: 40%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 5%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Sep 26, 8:17 AM EDT	Tornado Warning	LMK	Clark	13 min
Sep 26, 8:50 AM EDT	Severe Thunderstorm Warning	ILN	Lewis, Mason	12 min

The nearest sounding before it

Cncnati-Daytn, OH (KILN), launched 00:00Z, 10.7 hours before the alert went out and 130 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: 9 J/kg
Mixed-layer CIN: -128 J/kg
Mixed-layer LCL: 1410 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 223 m²/s²
0-3 km storm-relative helicity: 291 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

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

748 
WWUS20 KWNS 261044
SEL6
SPC WW 261044
KYZ000-OHZ000-261700-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 856
NWS STORM PREDICTION CENTER NORMAN OK
645 AM EDT MON SEP 26 2011

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

       CENTRAL KENTUCKY
       SOUTHWEST OHIO

EFFECTIVE THIS MONDAY MORNING AND AFTERNOON FROM 645 AM UNTIL 100
PM EDT.

TORNADOES...HAIL TO 0.5 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 45 STATUTE
MILES EAST AND WEST OF A LINE FROM 55 MILES EAST NORTHEAST OF
CINCINNATI OHIO TO 45 MILES SOUTHWEST OF LONDON KENTUCKY.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU6).

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.

DISCUSSION...QLCS WITH EMBEDDED MESOCYCLONES HAS RECENTLY
INTENSIFIED PERHAPS IN RESPONSE TO FORCING ASSOCIATED WITH VORTICITY
LOBE ROTATING INTO THE LOWER OH VALLEY.  RECENT SURFACE OBSERVATIONS
WITHIN INFLOW AIR MASS ACROSS CNTRL KY HAVE SHOWN GUSTY SURFACE
WINDS...SUGGESTING SOME COUPLING OF THE BOUNDARY LAYER WITH THE
HIGHER MOMENTUM FLOW ALOFT.  THOUGH INSTABILITY REMAINS
MARGINAL...THE INCREASED FORCING FOR ASCENT COUPLED WITH EFFECTIVE
SRH OF 400-500 M2/S2 SUGGESTS A RISK FOR TORNADOES AND DAMAGING
WINDS WITH THE QLCS.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
350. MEAN STORM MOTION VECTOR 22045.


...MEAD

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 25, 8:49 PM EDT	Mesoscale Discussion	SPC	Breckinridge, Bullitt, Butler, Caldwell, Calloway, Christian and 19 more	2 hr
Sep 26, 1:45 AM EDT	Mesoscale Discussion	SPC	Adair, Allen, Anderson, Barren, Boone, Bourbon and 55 more	3 hr
Sep 26, 2:16 PM EDT	Mesoscale Discussion	SPC	Floyd, Letcher, Martin, Pike	59 min

Nearby

Tornado Watches in Kentucky, 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.