Winter Storm in Wyoming, February 21 to 22, 2023

Name: Winter Storm in Wyoming, February 21 to 22, 2023
Start: 2023-02-21T09:00
End: 2023-02-22T23:00
Location: Wyoming

February 21 to 22, 2023 · NWS UNR · 6 events in 6 counties and zones

Where it happened

Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 6

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS UNR wrote it up.

A strong winter storm impacted the area, bringing significant snowfall, gusty winds, and a surge of Arctic air. A series of upper-level disturbances associated with the system overrode the Arctic air at the surface and produced snowfall for an extended period. The Arctic cold front dropped temperatures to near or below zero for an extended period. Snowfall amounts were in the six to 12 inch range across a good portion of northeastern Wyoming, with amounts tailing off some across far northeastern Wyoming. Minor blowing and drifting of snow occurred with breezy conditions. Wind chill values dropped to 20 below to 35 below zero during the event.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Rapid City, SD wrote its last area forecast discussion before the first event at Feb 21, 4:20 AM MST, 4 hours 40 minutes earlier.

Area forecast discussion, Feb 21, 4:20 AM MST, 4 hours 40 minutes before

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
420 AM MST Tue Feb 21 2023

.DISCUSSION...(Today Through Monday)
Issued at 132 AM MST Tue Feb 21 2023

The upper trough responsible for most of our snow this week is
pushing into the Pac NW. At the surface, low pressure sits over
central MT, with high pressure over the eastern Dakotas, and a
frontal boundary draped in between. Skies are becoming
increasingly cloudy, and a few snow showers have appeared along
the front. Radar indicates a broader area of snow over MT. Winds
are light and southeasterly, and temperatures are in the teens
and 20s.

Precipitation will spread into the northwestern CWA as frontogenesis
strengthens and shifts eastward into the Dakotas. Precip will begin
as snow this morning, but as the warm front pushes northeastward,
snow will mix with and/or change to rain, especially across southern
parts of the area. Snow across NW SD will quickly shift eastward by
this afternoon, but precip will linger over northeastern WY and
especially the Black Hills through the day. Froude number this
afternoon is supportive of upslope enhancement, and several inches
of snow may fall there just today. Before the next push of energy
moves in Wednesday, some places (especially NW SD) may see a break
or lessening of snowfall this afternoon and overnight. Ensemble
spreads for temperatures across the CWA are large for today (10-15
degrees), and will depend on where the front ends up. Expecting
highs to range from the 20s across NW SD (and therefore expecting
all snow there) to the low 50s across SW SD.

On Wednesday, the low pressure system will dig into the Rockies,
sending strong PVA over the northern plains. Considerable isentropic
lift will commence beneath coupled jets, and a large swath of snow
will expand over the northern plains. At the surface, very cold air
will spread southward, and northeasterly winds will become breezy.
Snow and some blowing snow, along with bitter cold temperatures,
will continue into Wednesday night. Upper wave will shift east
Wednesday night, with lift and moisture dissipating Thursday
morning. Snow and winds will gradually end from west to east
Thursday. However, bitter cold temperatures will linger into Friday,
before warmer air starts moving back in. With wind chills in the 20s
and 30s below zero, will need to consider wind chill headlines after
the storm.

All in all, snowfall forecast has stayed mostly the same, except for
a slight increase in amounts over SW and west central SD. Still
generally expecting 6 to 14 inches across much of the area, with the
lesser amounts being over far NW SD and northeastern WY, and the
greater amounts over the northern BH and south central SD. The
higher amounts over the northern BH can be attributed to the upslope
enhancement today; otherwise, that area can expect similar snow
amounts to the plains on Wednesday. Still could see locally higher
amounts over the northeastern foothills with some slight upslope
enhancement there from the breezy NE winds Wednesday.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Wednesday Morning)
Issued At 418 AM MST Tue Feb 21 2023

Snow will increase in coverage across parts of northeastern
Wyoming and far northwestern South Dakota this morning with
IFR/LIFR conditions, then will slowly spread across the rest of
northeastern WY and far western SD during the day today, with
widespread IFR conditions in -SN and BLSN tonight.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Storm Warning until 11 AM MST Thursday for SDZ001-002.
     Winter Storm Warning from 5 PM this afternoon to 11 AM MST
     Thursday for SDZ012>014-025>027-029>032-041>043-072>074.
     Winter Storm Warning until 11 AM MST Thursday for SDZ024-028.
     Winter Storm Warning from 8 PM MST /9 PM CST/ this evening to 11
     AM MST /noon CST/ Thursday for SDZ044-046-047-049.
WY...Winter Storm Warning from 5 PM this afternoon to 11 AM MST
     Thursday for WYZ054>056-058-071.
     Winter Storm Warning until 11 AM MST Thursday for WYZ057.
&&

DISCUSSION...Pojorlie
AVIATION...10

In the hours before

Local storm report, Feb 21, 8:01 AM MST, 59 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
801 AM MST TUE FEB 21 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0515 AM     SNOW             3 SE SAINT ONGE         44.52N 103.67W
02/21/2023  M1.3 INCH        LAWRENCE           SD   COCORAHS

            24-HOUR SNOWFALL.

0600 AM     SNOW             SUNDANCE                44.40N 104.37W
02/21/2023  M1.1 INCH        CROOK              WY   COCORAHS

            24-HOUR SNOWFALL.

0600 AM     SNOW             3 E NEWCASTLE           43.86N 104.14W
02/21/2023  M0.5 INCH        WESTON             WY   COCORAHS

            24-HOUR SNOWFALL.

0700 AM     SNOW             3 ESE CHEYENNE CROSSING 44.28N 103.81W
02/21/2023  M5.0 INCH        LAWRENCE           SD   COCORAHS

            24-HOUR SNOWFALL.

0720 AM     SNOW             5 SSE DWTN SPEARFISH    44.44N 103.81W
02/21/2023  M3.5 INCH        LAWRENCE           SD   COCORAHS

            24-HOUR SNOWFALL.

&&

07

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

6 winter storm. Local standard time, as filed.

Winter Storm, South Campbell

When: February 21, 9:00 AM MST to February 22, 9:00 PM MST
Where: South Campbell forecast zone
Reported by: CoCoRaHS
Coordinates: 44.248, -105.548 (the zone’s center; the record gives no point)

Winter Storm, Northern Campbell

When: February 21, 10:00 AM MST to February 22, 10:00 PM MST
Where: Northern Campbell forecast zone
Reported by: Emergency Manager
Coordinates: 44.248, -105.548 (the zone’s center; the record gives no point)

Winter Storm, Western Crook

When: February 21, 10:00 AM MST to February 22, 10:00 PM MST
Where: Western Crook forecast zone
Reported by: Trained Spotter
Coordinates: 44.589, -104.570 (the zone’s center; the record gives no point)

Winter Storm, Wyoming Black Hills

When: February 21, 10:00 AM MST to February 22, 10:00 PM MST
Where: Wyoming Black Hills forecast zone
Reported by: CoCoRaHS
Coordinates: 44.215, -104.569 (the zone’s center; the record gives no point)

Winter Storm, Northeastern Crook

When: February 21, 12:00 PM MST to February 22, 11:00 PM MST
Where: Northeastern Crook forecast zone
Reported by: Trained Spotter

Winter Storm, Weston

When: February 21, 2:00 PM MST to February 22, 9:00 PM MST
Where: Weston forecast zone
Reported by: CoCoRaHS
Coordinates: 43.841, -104.568 (the zone’s center; the record gives no point)

What these are

Winter Storm: A storm that brought snow, sleet or freezing rain at warning levels, usually over several hours or days.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Wyoming in 2023 Every state in 2023 This day in weather history Warnings in Wyoming, February 2023

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1074302, 1074301, 1074304, 1074305, 1074307, 1074306.