Alert archive / Nebraska / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 138, NWS Cheyenne, WY

August 8, 20204 counties in Nebraska

NWS Cheyenne, WY issued this severe thunderstorm warning at Aug 8, 2020, 6:27 PM MDT for 4 counties in Nebraska. It was in force for 18 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Aug 8, 2020, 6:27 PM MDT (00:27 UTC)
Expired
Aug 8, 2020, 6:45 PM MDT
In force
18 min
Issued by
NWS Cheyenne, WY
Area
Storm-based polygon
Hail
1.5 in
Wind
60.0 mph

Counties Box Butte County, NE, Morrill County, NE, Scotts Bluff County, NE, Sioux County, NE

The radar

The Cheyenne radar (KCYS), 156 km from the middle of the area, began a volume at 00:28 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 8, 5:00 PM MDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Rapid City, SD (KUNR), launched 00:00Z, 0.5 hours before the alert went out and 226 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-pSkew-T log-p diagram, Rapid City, SD at 00:00Z on 2020-08-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1865 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Rapid City, SD at 00:00Z on 2020-08-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 58 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
1865 J/kg
Mixed-layer CIN
-40 J/kg
Mixed-layer LCL
1835 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
58 m²/s²
0-3 km storm-relative helicity
94 m²/s²
Significant tornado parameter
0.1
Supercell composite
2.6

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Cheyenne, WY wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 8, 5:57 PM MDT, 30 minutes earlier.

Area forecast discussion, Aug 8, 5:57 PM MDT, 30 minutes before
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Hazardous weather outlook, Aug 8, 3:43 PM MDT, 2 hours 44 minutes before
Hazardous Weather Outlook
National Weather Service Cheyenne WY
343 PM MDT Sat Aug 8 2020

WYZ104-105-109>115-092145-
Ferris/Seminoe/Shirley Mountains-Shirley Basin-
Central Carbon County-North Snowy Range Foothills-
Southwest Carbon County-Sierra Madre Range-
Upper North Platte River Basin-Snowy Range-Laramie Valley-
343 PM MDT Sat Aug 8 2020

This hazardous weather outlook is for portions of south central
Wyoming and southeast Wyoming.

.DAY ONE...THIS AFTERNOON AND TONIGHT

Gusty winds and low afternoon humidity will lead to increased fire
danger across parts of Carbon County. A Red Flag Warning remains in
effect until 8 PM this evening.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

Critical fire weather conditions can be expected on a daily basis
through next week. A Red Flag Warning is in effect from 9 AM through
8 PM Sunday.

.Spotter information statement...

Spotter activation will not be required.

NEZ002-003-019>021-054-055-095-096-WYZ101>103-106>108-116>119-
092145-
Dawes-Box Butte-Scotts Bluff County-Banner County-Morrill-
Kimball County-Cheyenne-North Sioux-South Sioux-
Converse County Lower Elevations-Niobrara County-
North Laramie Range-
Central Laramie Range and Southwest Platte County-
East Platte County-Goshen County-South Laramie Range-
South Laramie Range Foothills-Central Laramie County-
East Laramie County-
343 PM MDT Sat Aug 8 2020

This hazardous weather outlook is for the western Nebraska
Panhandle...east central Wyoming and southeast Wyoming.

.DAY ONE...THIS AFTERNOON AND TONIGHT

Isolated to scattered thunderstorms will develop east of the Laramie
Range this afternoon and move east into the Nebraska Panhandle through
early evening. Some of these storms could become severe with large
hail and damaging downburst winds.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

Isolated to widely scattered thunderstorms will be possible each day
east of the Laramie Range Monday through Wednesday.

.Spotter information statement...

Spotter activation may be required across the eastern Wyoming
plains and western Nebraska Panhandle between 4 PM and 8 PM this
evening.

In the hours before

Local storm report, Aug 8, 5:14 PM MDT, 1 hour 13 minutes before
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Special weather statement, Aug 8, 5:24 PM MDT, 1 hour 3 minutes before
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Local storm report, Aug 8, 5:57 PM MDT, 30 minutes before
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Local storm report, Aug 8, 6:11 PM MDT, 16 minutes before
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Local storm report, Aug 8, 6:12 PM MDT, 15 minutes before
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Special weather statement, Aug 8, 6:12 PM MDT, 15 minutes before
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The office that day

Everything else NWS Cheyenne, WY issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 9, 1:33 AM MDTFire Weather WatchCYS13 hr
Aug 9, 2:32 PM MDTRed Flag WarningCYS29 hr
Aug 8, 6:02 PM MDTSevere Thunderstorm WarningCYSDawes28 min
Aug 8, 6:12 PM MDTSpecial Weather StatementCYSScotts Bluff33 min
Aug 8, 6:29 PM MDTSevere Thunderstorm WarningCYSBox Butte, Morrill, Scotts Bluff, Sioux19 min

Nearby

Severe Thunderstorm Warnings in Nebraska, 2020Every severe thunderstorm warning in 2020

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.