Alert archive / Nebraska / Special Weather Statements in 2020

Special Weather Statement, NWS Cheyenne, WY

August 6, 2020Sioux County, Nebraska

NWS Cheyenne, WY issued this special weather statement at Aug 6, 2020, 3:36 PM MDT for Sioux County, Nebraska. It was in force for 39 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 6, 2020, 3:36 PM MDT (21:36 UTC)
Expired
Aug 6, 2020, 4:15 PM MDT
In force
39 min
Issued by
NWS Cheyenne, WY

County Sioux County, NE

The radar

The Cheyenne radar (KCYS), 160 km from the middle of the area, began a volume at 21:39 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 nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 9.6 hours before the alert went out and 308 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, Denver, CO at 12:00Z on 2020-08-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 116 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, Denver, CO at 12:00Z on 2020-08-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 3 square meters per square second.1939Sfc1 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
116 J/kg
Mixed-layer CIN
-360 J/kg
Mixed-layer LCL
2239 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
3 m²/s²
0-3 km storm-relative helicity
53 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement 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 special weather statement went out at Aug 6, 3:19 PM MDT, 17 minutes earlier.

Area forecast discussion, Aug 6, 3:19 PM MDT, 17 minutes before
Area Forecast Discussion
National Weather Service Cheyenne WY
319 PM MDT Thu Aug 6 2020

.SHORT TERM...(This evening through Friday)
Issued at 223 PM MDT Thu Aug 6 2020

Summary: Scattered thunderstorms expected this afternoon across
the High Plains of Southeast Wyoming and the western Nebraska
Panhandle. A few of these thunderstorms could be strong to severe
with up to ping pong sized hail and wind gusts of 60 mph possible.
Localized downpours will also be likely with the the
thunderstorms but flash flooding risk is low given storm motion
speed. Strong to briefly severe storms will diminish in
probability and coverage through mid-evening hours. In addition to
the strong/severe storm risk, critical fire weather conditions
are occurring along and west of the Laramie Mountains this
afternoon.

Weather Details: Increasing instability of surface based parcels
continues to occur this afternoon that is allowing for
thunderstorms, some strong to severe, to develop as of early this
afternoon. Effective deep layer shear is near 30 knots and this
will allow for some brief pulse to semi-displaced
updraft/downdraft interfacing for greater storm longevity and
enhanced strength. The combined moderately favorable
thermodynamics with a weak shortwave trough within the ridge axis
will also assist in brief robust convection.

Drier air will shift across the region Friday with less of a
shortwave trough signal vs. today but a few isolated showers and
storms could be possible across far north Niobrara County. The
Drier air will support greater area of critical fire weather
danger Friday and kept Red Flag configuration as is for now. A
Fire Weather Watch may be needed for Saturday but winds appear
marginal at this time with confidence low.

.LONG TERM...(Friday through Wednesday)
Issued at 324 AM MDT Thu Aug 6 2020

Not much in the way of rainfall seen over the CWA through the
period with an upper high over the southern CONUS keeping the
stronger westerlies and embedded shortwaves riding generally to
the north. One wave will swing across the northern plains Sunday
and push a cool front across the CWA resulting in some cooling for
Monday. The upper high then builds over the southern Rockys by
midweek keeping any convection limited. Right now best chances
look to be late Tuesday though very isolated activity cannot be
ruled out at other times if any other hard-to-discern shortwaves
clip the area.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1128 AM MDT Thu Aug 6 2020

VFR flight conditions anticipated for this afternoon through 0Z
for all terminals. A weak upper level disturbance will create
VCSH and VCTS for the WY terminals this afternoon, but flight
categories are not expected to change, however wind gusts up to 25
knots are possible for the WY terminals through 0Z at times from
the rain shower activity. AIA, CDR, and SNY could see VCTS by 23Z
this afternoon with the possibility of thunderstorms causing
reduced VIS from approximately 0Z-2Z. BFF may see VCTS a little
earlier from 21Z to 0Z. Expect wind gusts up to 20-25 knots at
times for the Western NE Panhandle terminals this afternoon.

&&

.FIRE WEATHER...
Issued at 223 PM MDT Thu Aug 6 2020

Critical fire weather conditions are ongoing across Carbon and
portions of Albany Counties this afternoon with winds gusts
over 25 mph and humidity values near or below 15 percent. These
conditions will remain in place through mid-evening with
humidity increasing overnight. Another critical fire weather
day Friday across a larger region of Southeast Wyoming. Will
need to monitor for Fire Weather Watch on Saturday but winds
will be marginal in the 15-20 mph range.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 8 PM MDT this evening for WYZ303>308.

     Red Flag Warning from 11 AM to 8 PM MDT Friday for WYZ303>308.

     Red Flag Warning from 11 AM to 4 PM MDT Friday for WYZ301-302-
     309.

NE...None.
&&

SHORT TERM...JSA
LONG TERM...RE
AVIATION...BW
FIRE WEATHER...JSA
Hazardous weather outlook, Aug 6, 4:09 AM MDT, 11 hours 27 minutes before
Hazardous Weather Outlook
National Weather Service Cheyenne WY
409 AM MDT Thu Aug 6 2020

WYZ104-105-109>115-071015-
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-
409 AM MDT Thu Aug 6 2020

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

.DAY ONE...TODAY AND TONIGHT

Dry and breezy conditions expected with fire weather conditions
the primary concern. A Red Flag Warning is in place today.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

Red Flag Warning is in place Friday, with more warnings likely
over the course of the next week.

.Spotter information statement...

Spotter activation will not be required.

NEZ002-003-019>021-054-055-095-096-WYZ101>103-106>108-116>119-
071015-
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-
409 AM MDT Thu Aug 6 2020

This hazardous weather outlook is for portions of panhandle
Nebraska...western Nebraska...east central Wyoming and southeast
Wyoming.

.DAY ONE...TODAY AND TONIGHT

Scattered afternoon and evening thunderstorms will develop
Thursday; some may be strong to severe. Strong winds will be the
primary threat, with large hail possible over east-central
Wyoming and the western Nebraska Panhandle.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

Storms become isolated and confined to the mountains Friday and
Saturday. Fire weather concerns beginning Friday for areas along
and near the Laramie Range.

.Spotter information statement...

Spotter activation will not be required.

In the hours before

Special weather statement, Aug 6, 2:31 PM MDT, 1 hour 5 minutes before
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Special weather statement, Aug 6, 2:42 PM MDT, 54 minutes before
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Special weather statement, Aug 6, 3:10 PM MDT, 26 minutes before
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Special weather statement, Aug 6, 3:16 PM MDT, 20 minutes before
Special Weather Statement
National Weather Service Cheyenne WY
316 PM MDT Thu Aug 6 2020

NEZ054-062200-
Kimball NE-
316 PM MDT Thu Aug 6 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN KIMBALL COUNTY UNTIL
400 PM MDT...

At 316 PM MDT, Doppler radar was tracking a strong thunderstorm near
Panorama Point, or 20 miles southwest of Kimball, moving southeast at
10 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm.

This storm will remain over mainly rural areas of southwestern
Kimball County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4113 10392 4102 10358 4100 10359 4100 10402
TIME...MOT...LOC 2116Z 322DEG 10KT 4102 10392

Trudel
Special weather statement, Aug 6, 3:30 PM MDT, 6 minutes before
Special Weather Statement
National Weather Service Cheyenne WY
330 PM MDT Thu Aug 6 2020

NEZ095-WYZ102-062215-
North Sioux NE-Niobrara County WY-
330 PM MDT Thu Aug 6 2020

...SIGNIFICANT WEATHER ADVISORY FOR WESTERN SIOUX AND SOUTHEASTERN
NIOBRARA COUNTIES UNTIL 415 PM MDT...

At 329 PM MDT, Doppler radar was tracking a strong thunderstorm 9
miles northeast of Lusk, moving east at 10 mph.

Penny size hail and wind gusts up to 50 mph will be possible with
this storm.

This storm will remain over mainly rural areas of western Sioux and
southeastern Niobrara Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4279 10435 4290 10434 4296 10401 4268 10401
TIME...MOT...LOC 2129Z 283DEG 7KT 4283 10430

Trudel
Special weather statement, Aug 6, 3:36 PM MDT, 0 minutes before
Special Weather Statement
National Weather Service Cheyenne WY
336 PM MDT Thu Aug 6 2020

NEZ095-WYZ102-108-062215-
North Sioux NE-Goshen County WY-Niobrara County WY-
336 PM MDT Thu Aug 6 2020

...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL SIOUX...SOUTHERN
NIOBRARA AND NORTHEASTERN GOSHEN COUNTIES UNTIL 415 PM MDT...

At 336 PM MDT, Doppler radar was tracking a strong thunderstorm near
Prairie Center, or 16 miles southeast of Lusk, moving southeast at 15
mph.

Penny size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Prairie Center.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4253 10442 4264 10434 4261 10394 4235 10414
TIME...MOT...LOC 2136Z 301DEG 14KT 4256 10429

Trudel

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 5, 7:09 PM MDTSpecial Weather StatementCYSNiobrara51 min
Aug 5, 7:55 PM MDTSpecial Weather StatementCYSNiobrara50 min
Aug 5, 8:30 PM MDTSevere Thunderstorm WarningCYSNiobrara45 min
Aug 6, 3:08 AM MDTRed Flag WarningCYS41 hr
Aug 6, 1:28 PM MDTSpecial Weather StatementCYSLaramie47 min
Aug 6, 2:31 PM MDTSpecial Weather StatementCYSLaramie44 min
Aug 6, 2:42 PM MDTSpecial Weather StatementCYSNiobrara48 min
Aug 6, 3:30 PM MDTSpecial Weather StatementCYSNiobrara45 min
Aug 6, 4:19 PM MDTSpecial Weather StatementCYSGoshen41 min
Aug 6, 4:29 PM MDTSevere Thunderstorm WarningCYSGoshen, Platte26 min
Aug 6, 5:42 PM MDTSevere Thunderstorm WarningCYSGoshen, Niobrara33 min
Aug 5, 6:11 PM MDTSpecial Weather StatementCYSMorrill49 min
Aug 5, 6:13 PM MDTSevere Thunderstorm WarningCYSMorrill18 min
Aug 5, 6:18 PM MDTSpecial Weather StatementCYSDawes42 min
Aug 5, 6:50 PM MDTSpecial Weather StatementCYSScotts Bluff40 min
Aug 5, 7:37 PM MDTSpecial Weather StatementCYSCheyenne38 min
Aug 5, 7:52 PM MDTSevere Thunderstorm WarningCYSCheyenne27 min
Aug 5, 7:57 PM MDTSpecial Weather StatementCYSSioux48 min
Aug 5, 9:00 PM MDTSpecial Weather StatementCYSDawes45 min
Aug 5, 9:39 PM MDTSpecial Weather StatementCYSDawes51 min
Aug 5, 10:16 PM MDTSpecial Weather StatementCYSBox Butte59 min
Aug 5, 10:19 PM MDTSpecial Weather StatementCYSDawes56 min
Aug 5, 11:15 PM MDTSpecial Weather StatementCYSMorrill45 min
Aug 6, 2:26 PM MDTSpecial Weather StatementCYSKimball49 min
Aug 6, 2:35 PM MDTSevere Thunderstorm WarningCYSKimball40 min
Aug 6, 3:10 PM MDTSpecial Weather StatementCYSBanner50 min
Aug 6, 3:16 PM MDTSpecial Weather StatementCYSKimball44 min
Aug 6, 3:51 PM MDTSpecial Weather StatementCYSBanner39 min
Aug 6, 4:33 PM MDTSpecial Weather StatementCYSSioux42 min
Aug 6, 5:14 PM MDTSpecial Weather StatementCYSCheyenne46 min
Aug 6, 5:30 PM MDTSpecial Weather StatementCYSSioux45 min
Aug 6, 5:46 PM MDTSpecial Weather StatementCYSCheyenne44 min

Nearby

Special Weather Statements in Nebraska, 2020Every special weather statement 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.