Alert archive / Wyoming / Winter Weather Advisories in 2021

Winter Weather Advisory 4, NWS Cheyenne, WY

January 21, 20214 counties in Wyoming

NWS Cheyenne, WY issued this winter weather advisory at Jan 21, 2021, 10:29 PM MST for 4 counties in Wyoming. It was in force for 10 hr.

The area

The counties it named.

The facts

Issued
Jan 21, 2021, 10:29 PM MST (05:29 UTC)
Expired
Jan 22, 2021, 8:00 AM MST
In force
10 hr
Issued by
NWS Cheyenne, WY

Counties Albany County, WY, Goshen County, WY, Laramie County, WY, Platte County, WY

The radar

The Cheyenne radar (KCYS), 72 km from the middle of the area, began a volume at 05:30 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 00:00Z, 5.5 hours before the alert went out and 258 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 00:00Z on 2021-01-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 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 00:00Z on 2021-01-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 98 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2063 m above ground
0-6 km bulk shear
70 kt
0-1 km storm-relative helicity
98 m²/s²
0-3 km storm-relative helicity
201 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this winter weather advisory 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 winter weather advisory went out at Jan 21, 4:49 PM MST, 5 hours 40 minutes earlier.

Area forecast discussion, Jan 21, 4:49 PM MST, 5 hours 40 minutes before
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Hazardous weather outlook, Jan 21, 1:23 AM MST, 21 hours 6 minutes before
Hazardous Weather Outlook
National Weather Service Cheyenne WY
Issued by National Weather Service Riverton WY
123 AM MST Thu Jan 21 2021

WYZ106-110-116-117-221200-
Central Laramie Range and Southwest Platte County-
North Snowy Range Foothills-South Laramie Range-
South Laramie Range Foothills-
123 AM MST Thu Jan 21 2021

...High Wind Warning in Effect until 11 AM Thursday...

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

.DAY ONE...TODAY AND TONIGHT

High winds occurring, but diminishing by mid day. Please see the
High Wind Warning for details.

Some snow possible tonight, but accumulations should be light.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

A better chance for accumulating snow will return late Friday
into early Sunday. 4+ inches are possible in the Sierra Madre and
Medicine Bow Mountains.

.Spotter information statement...

Spotters are encouraged to report wind gusts and any damage
through Thursday morning.

WYZ104-105-109-115-221200-
Ferris/Seminoe/Shirley Mountains-Shirley Basin-
Central Carbon County-Laramie Valley-
123 AM MST Thu Jan 21 2021

...High Wind Warning in Effect until 5 AM Thursday...

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

.DAY ONE...TODAY AND TONIGHT

Winds diminishing today.

Some snow possible tonight, but accumulation is expected to be
light.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

A better chance for accumulating snow will return late Friday
into early Sunday.

.Spotter information statement...

Spotters are encouraged to report wind gusts and any damage
through Thursday morning.

NEZ002-003-019>021-054-055-095-096-WYZ101>103-111>114-221200-
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-Southwest Carbon County-Sierra Madre Range-
Upper North Platte River Basin-Snowy Range-
123 AM MST Thu Jan 21 2021

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

.DAY ONE...TODAY AND TONIGHT

Some snow possible tonight, but accumulations are expected to be
light.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

A better chance for accumulating snow will Friday into early
Sunday.

.Spotter information statement...

Spotter activation will not be needed.

WYZ107-108-118-119-221200-
East Platte County-Goshen County-Central Laramie County-
East Laramie County-
123 AM MST Thu Jan 21 2021

...High Wind Warning in Effect until 11 AM Thursday...

This hazardous weather outlook is for portions of southeast
Wyoming.

.DAY ONE...TODAY AND TONIGHT

High winds diminishing by midday.

Some snow possible tonight; but accumulations are expected to be
light.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

A better chance for accumulating snow late Friday into early
Sunday.

.Spotter information statement...

Spotters are encouraged to report wind gusts and any damage
through Thursday morning.

In the hours before

Special weather statement, Jan 21, 10:00 PM MST, 29 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jan 22, 3:22 AM MSTWinter Storm WarningCYSAlbany, Carbon47 hr
Jan 22, 12:46 PM MSTWinter Weather AdvisoryCYSAlbany, Carbon, Converse, Laramie, Niobrara, Platte38 hr

Nearby

Winter Weather Advisories in Wyoming, 2021Every winter weather advisory 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.