Alert archive / Nebraska / Severe Thunderstorm Watches in 2021

Severe Thunderstorm Watch 268

June 13, 20218 counties in Nebraska; 4 counties in Wyoming

The Storm Prediction Center issued this severe thunderstorm watch at Jun 13, 2021, 3:04 PM MDT for 8 counties in Nebraska; 4 counties in Wyoming. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Jun 13, 2021, 3:04 PM MDT (21:04 UTC)
Expired: Jun 13, 2021, 10:00 PM MDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 65 kt

Counties Banner County, NE, Box Butte County, NE, Cheyenne County, NE, Dawes County, NE, Kimball County, NE, Morrill County, NE, Scotts Bluff County, NE, Sioux County, NE, Goshen County, WY, Laramie County, WY, Niobrara County, WY, Platte County, WY

The radar

The Cheyenne radar (KCYS), 123 km from the middle of the area, began a volume at 21:08 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: 10%
One or more EF2 to EF5 tornadoes: 2%
Ten or more severe wind reports: 40%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 30%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jun 13, 4:53 PM MDT	Severe Thunderstorm Warning	CYS	Goshen	32 min
Jun 13, 4:58 PM MDT	Severe Thunderstorm Warning	CYS	Laramie	47 min
Jun 13, 5:13 PM MDT	Severe Thunderstorm Warning	CYS	Scotts Bluff, Sioux	47 min
Jun 13, 5:43 PM MDT	Severe Thunderstorm Warning	CYS	Laramie	41 min
Jun 13, 5:50 PM MDT	Severe Thunderstorm Warning	CYS	Box Butte, Dawes, Sioux	55 min
Jun 13, 5:58 PM MDT	Severe Thunderstorm Warning	CYS	Scotts Bluff, Sioux	47 min
Jun 13, 6:42 PM MDT	Severe Thunderstorm Warning	CYS	Box Butte, Dawes, Sioux	48 min
Jun 13, 7:27 PM MDT	Severe Thunderstorm Warning	CYS	Box Butte, Dawes, Sioux	48 min
Jun 13, 7:32 PM MDT	Severe Thunderstorm Warning	CYS	Dawes	43 min
Jun 13, 7:38 PM MDT	Severe Thunderstorm Warning	CYS	Box Butte, Cheyenne, Morrill	52 min
Jun 13, 8:52 PM MDT	Severe Thunderstorm Warning	CYS	Morrill	53 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

Rapid City, SD (KUNR), launched 12:00Z, 9.1 hours before the alert went out and 238 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: 10 J/kg
Mixed-layer CIN: -354 J/kg
Mixed-layer LCL: 2455 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: -6 m²/s²
0-3 km storm-relative helicity: -1 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

As transmitted.

914 
WWUS20 KWNS 132102
SEL8  
SPC WW 132102
NEZ000-WYZ000-140400-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 268
NWS Storm Prediction Center Norman OK
305 PM MDT Sun Jun 13 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Nebraska Panhandle
  Southeast Wyoming

* Effective this Sunday afternoon and evening from 305 PM until
  1000 PM MDT.

* Primary threats include...
  Scattered damaging winds and isolated significant gusts to 75
    mph possible
  Isolated very large hail events to 2 inches in diameter possible

SUMMARY...Initial discrete cells should persist across far southeast
Wyoming, while additional storms form over the northwest Nebraska
Panhandle. This activity should into an east-southeast moving
cluster this evening. Large hail transitioning to predominately
severe wind gusts are the main hazards.

The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 50 miles north
northwest of Cheyenne WY to 15 miles north of Alliance NE. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU8).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for 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. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 264...WW 265...WW
266...WW 267...

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 65 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
29020.

...Grams

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 13, 1:16 PM MDT	Mesoscale Discussion	SPC	Banner, Box Butte, Cheyenne, Dawes, Garden, Kimball and 4 more	89 min

Nearby

Severe Thunderstorm Watches in Nebraska, 2021 Severe Thunderstorm Watches in Wyoming, 2021 Every severe thunderstorm watch in 2021

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.