Alert archive / Nebraska / Tornado Watches in 2011

Tornado Watch 527

June 20, 201110 counties in Kansas; 24 counties in Nebraska

The Storm Prediction Center issued this tornado watch at Jun 20, 2011, 7:40 PM CDT for 10 counties in Kansas; 24 counties in Nebraska. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Jun 20, 2011, 7:40 PM CDT (00:40 UTC)
Expired: Jun 20, 2011, 10:33 PM CDT
In force: 3 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 34 counties

Decatur County, KS, Graham County, KS, Jewell County, KS, Mitchell County, KS, Norton County, KS, Osborne County, KS, Phillips County, KS, Rooks County, KS, Sheridan County, KS, Smith County, KS, Adams County, NE, Buffalo County, NE, Clay County, NE, Dawson County, NE, Fillmore County, NE, Franklin County, NE, Frontier County, NE, Furnas County, NE, Gosper County, NE, Hall County, NE, Hamilton County, NE, Harlan County, NE, Howard County, NE, Kearney County, NE, Merrick County, NE, Nance County, NE, Nuckolls County, NE, Phelps County, NE, Polk County, NE, Red Willow County, NE, Sherman County, NE, Thayer County, NE, Webster County, NE, York County, NE

The radar

The Grand Island radar (KUEX), 73 km from the middle of the area, began a volume at 00:58 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: 50%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 20%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 50%
One or more hailstones of 2 inches or more: 20%
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
Jun 20, 8:11 PM CDT	Severe Thunderstorm Warning	GID	Furnas	34 min
Jun 20, 8:15 PM CDT	Severe Thunderstorm Warning	GLD	Red Willow	21 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

N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 0.7 hours before the alert went out and 143 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: 109 J/kg
Mixed-layer CIN: -135 J/kg
Mixed-layer LCL: 552 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 271 m²/s²
0-3 km storm-relative helicity: 471 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.

564 
WWUS20 KWNS 210044
SEL7
SPC WW 210044
KSZ000-NEZ000-210700-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 527
NWS STORM PREDICTION CENTER NORMAN OK
740 PM CDT MON JUN 20 2011

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

       NORTH CENTRAL KANSAS
       SOUTH CENTRAL NEBRASKA

EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 740 PM UNTIL
200 AM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 90 STATUTE
MILES EITHER SIDE OF A LINE FROM 30 MILES NORTHWEST OF KEARNEY
NEBRASKA TO 70 MILES SOUTH OF HASTINGS NEBRASKA.  FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU7).

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 524...WW 525...WW 526...

DISCUSSION...TSTMS WITH THE POTENTIAL FOR A FEW TORNADOES AND LARGE
HAIL MAY PERSIST IN NE QUADRANT OF STRONG UPR VORT NOW NEAR HLC.
DEVELOPMENT MAY FOCUS ALONG STNRY BOUNDARY EXTENDING WSW/ENE ACROSS
S CNTRL NEB...BUT ALSO FARTHER E IN ZONE OF GREATER LOW LVL MOISTURE
AHEAD OF WEAK COLD FRONT IMMEDIATELY AHEAD OF THE VORT OVER N CNTRL
KS.  STORM MOTION MAY BE ERRATIC GIVEN LARGE SPATIAL VARIATION OF
WIND FIELD NEAR VORT...AND GIVEN PRESENCE OF LOW LVL BOUNDARIES THAT
WILL FORCE PROPAGATION ALONG SAME.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 20015.


...CORFIDI

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 20, 7:21 PM CDT	Mesoscale Discussion	SPC	Decatur, Norton	24 min
Jun 20, 7:46 PM CDT	Mesoscale Discussion	SPC	Allen, Anderson, Atchison, Bourbon, Brown, Chautauqua and 25 more	59 min
Jun 20, 8:32 PM CDT	Tornado Watch	SPC	Allen, Anderson, Atchison, Bourbon, Brown, Chautauqua and 25 more	4 hr
Jun 20, 9:46 PM CDT	Severe Thunderstorm Watch	SPC	Bourbon, Cherokee, Crawford	9 hr

Nearby

Tornado Watches in Nebraska, 2011 Tornado Watches in Kansas, 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.