Widespread snowfall occurred over much of southeast Wyoming on the 21st through the 23rd. Heaviest snowfall occurred over much of Carbon County in south-central Wyoming with blizzard conditions leading to an extended closure of Interstate 80 through the area.
Every event with a place to put it; 26 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
The episode as NWS CYS wrote it up.
Widespread snowfall occurred over much of southeast Wyoming on the 21st through the 23rd. Heaviest snowfall occurred over much of Carbon County in south-central Wyoming with blizzard conditions leading to an extended closure of Interstate 80 through the area. Numerous search and rescues were conducted for stranded motorists along the roadway.
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 Cheyenne, WY wrote its last area forecast discussion before the first event at Feb 20, 4:50 AM MST, 10 minutes earlier.
Area Forecast Discussion
National Weather Service Cheyenne WY
450 AM MST Mon Feb 20 2023
...STRONG WIND EVENT CONTINUES TODAY INTO TOMORROW, THEN
TRANSITIONS INTO A HIGH IMPACT WINTER STORM TUESDAY NIGHT INTO
EARLY THURSDAY. DANGEROUS WIND CHILLS TO FOLLOW ACCUMULATING
SNOWFALL...
.SHORT TERM...(Today through Wednesday Night)
Issued at 400 AM MST Mon Feb 20 2023
The short to medium range forecast has very little changes to
speak on for this forecast package discussion. Current winds and
wind gusts are quite strong due to very steep pressure gradients
across portions of southeast WY. Have not changed any of the high
wind headlines as overnight wind gusts along the I-80 corridors
for the Summit and Elk Mountain/Arlington areas have been observed
at 60-75mph. The I-25 corridor has also observed wind gusts near
60mph overnight at times for the Bordeaux area.
Northwest flow aloft will persist for the remainder of today into
Tuesday, with mountain wave signatures being well advertised on
model guidance. There will be occasional lulls in the maximum wind
gusts for areas under the high wind headlines, but the timeline of
this dissipating is unlikely until Tuesday afternoon for most
areas. Orographic enhancement of snow shower activity continues to
be forecast for the Snowy and Sierra Madre Mtns as shortwaves
riding along this northwest flow aloft propagate across the
region. The Winter Storm Warning headlines for these two forecast
zones remain on track as strong winds, reduced visibilities, and
heavy snowfall accumulations are expected through Thursday
morning.
Please read the previous forecast discussion for a more thorough
analysis of the atmospheric setup leading to our anticipated
snowfall from Tuesday night into Wednesday night. Model guidance
has persisted with a strong signal for a medium to high impact
threshold for a winter storm followed by bitter wind chill values
on Wednesday night into early Thursday. Ensemble regimes continue
their upward trend of clustering for mean average snowfall in the
winter storm warning criteria for our cwa. Once the strong cold
front pushes south through our area Tuesday into late Tuesday
evening, the light rain showers that are forecast for the onset of
precipitation will quickly transition to snow. The most difficult
portion of the forecast will be determining where the
frontogenetic bands persist across our cwa. The GFS deterministic
highlights a large section of southeast Wyoming seeing very
aggressive snowfall totals when referencing Kuchera ratio method
versus the typical 10:1 ratio. Another factor in the weather
forecast is how small the snowfall dendrites become due to the
very cold air that will infiltrate the region aloft. This could
impact the snowfall totals as the snow depth may not reflect how
much moisture is present for the area during peak snowfall rates.
Several locations could see localized areas of greater than 1 foot
if model trends continue with snowfall rates of 1+ inch/hr. Have
decided to upgrade a majority of the W.S.A. headlines to a winter
storm warning. There will be stronger wind gusts that pick up
across our western forecast zones on Wednesday. With this in mind,
combined with the forecast moderate to heavy snowfall rates,
confidence of blizzard conditions were present. Decided to go with
a blizzard headline to reflect this. Once the snowfall winds down
late Wednesday, bitter cold temperatures and wind chills are
anticipated to settle in. Given the trends in model guidance,
there is a high probability of a wind chill headline issuance
after snowfall winds down Wednesday night into early Thursday.
.LONG TERM...(Thursday through next Monday) Issued at 400 AM MST
Mon Feb 20 2023
Overview: Very cold wind chill values Thursday morning should be the
last chapter of the impactful weather that has impacted the
region. Temperature forecast has remained on par as minimum
temperatures Thursday morning should be in the teens below zero
for much of the region. A stiff, northwest wind will create wind
chill values that should warrant wind chill highlights, if this
forecast remains on track. What should be a widespread snowpack
across much of the region should aid in keeping temperatures on
the colder side of the spectrum on Thursday.
Discussion: As mentioned, Thursday should be the last day of the
hazardous weather associated with the active pattern that
developed across the region. If current runs of the long range
models, especially the GFS pan out, a quick return to winter
weather in the form of blowing snow and high winds return over the
weekend with the GFS showing a very strong Colorado low near the
ideal benchmark location for significant snowfall to impact SE
Wyoming and the Nebraska Panhandle. Confidence in this scenario is
extremely low as this just now getting into the day seven
timeframe and only the GFS is showing this solution. The ECMWF
brings a weaker system through the region but this still brings a
chance of widespread snow to the region.
&&
.AVIATION...(For the 12Z TAFS through Tuesday morning)
Issued at 400 PM MST Sun Feb 19 2023
Although VFR conditions are expected across all terminals through
the valid TAF period, LLWS and high wind gusts will be the main
aviation hazards for the terminals. The strongest wind gusts will be
across all the Wyoming terminals and after a lull in the wind speeds
through the early morning hours wind gusts will exceed 40 knots
between 14-16z at all terminals, with these strong winds expected to
last through the majority of this TAF period. Isolated wind gusts
of +50 knots will be possible. Winds will be around 10 to 15
knots less across the Nebraska TAF sites but with main wind gusts
ranging between 30 to 35 knots.
&&
.FIRE WEATHER...
Issued at 321 AM MST Mon Feb 20 2023
Fire weather concerns will remain low as cool and dry air persists
today and Tuesday. Very strong winds will be present for several
FWZs Monday and Tuesday, but minimum RH values will be 30-40
percent for fuels east of the Laramie Range. Cold temperatures and
snowfall will occur Tuesday night into Thursday, keeping fire
concerns low.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Storm Warning from 2 PM Tuesday to 5 AM MST Thursday for
WYZ101>103-106>108-111-113-116>119.
High Wind Warning until 8 AM MST Tuesday for WYZ101-105-107-108-
115-118-119.
High Wind Warning until 2 PM MST Tuesday for WYZ104-106-109-110-
116-117.
Blizzard Warning from 2 PM Tuesday to 5 AM MST Thursday for
WYZ104-105-109-110.
Winter Storm Warning until 5 AM MST Thursday for WYZ112-114.
NE...Winter Storm Warning from 2 PM Tuesday to 5 AM MST Thursday for
NEZ002-003-019>021-054-095-096.
&&
SHORT TERM...BW
LONG TERM...AW
AVIATION...TJT
FIRE WEATHER...BWThe national radar mosaic for the moment the first event began.
10 extreme cold/wind chill, 7 winter storm, 4 heavy snow, 4 blizzard, 1 winter weather. Local standard time, as filed.
Numerous SNOTEL sites estimated between 22 and 42 inches of snow accumulation. Med Bow SNOTEL site (elevation 10510 feet) estimated 42 inches of snow accumulation with 2.8 inches of snow water equivalent and 15:1 snow to liquid ratios.
Numerous SNOTEL sites estimated between 20 and 48 inches of snow accumulation. Old Battle SNOTEL site (elevation 10000 feet) estimated 48 inches of snow accumulation with 3.2 inches of snow water equivalent and 15:1 snow to liquid ratios.
COOP observer 4 miles north of Saratoga reported a storm total snow accumulation of 11 inches.
WYDOT reported 6 inches of snowfall in Baggs with 1 to 2 foot drifts just outside of town. Received reports of 7-foot drifts north of Baggs along highway WY-789.
CoCoRaHS observer located 3 miles east of Douglas reported a 2-day snow total of 12.3 inches. Additional observers near Glenrock reported 6 to 9 inches of accumulation during this time. Interstate 25 was closed between Douglas and Casper for an extended period of time due to winter conditions.
Estimated 5 to 8 inches of snow accumulation near Lusk based on nearby COOP and CoCoRaHS observers.
La Prele Creek SNOTEL site (elevation 8375 feet) estimated 18 inches of snow accumulation with 1 inch of snow water equivalent and 18:1 snow to liquid ratios.
CoCoRaHS observer located 22 miles east-northeast of Laramie near Horse Creek reported a storm total snow accumulation of 10 inches.
Interstate 80 was closed between Cheyenne and Laramie for an extended period of time due to winter conditions.
CoCoRaHS observer located 1 mile north of Wheatland reported a storm total snow accumulation of 10.5 inches. Interstate 25 between Wheatland and Douglas was closed for an extended period of time due to winter conditions.
CoCoRaHS observer located 20 miles southwest of Wheatland reported a storm total snow accumulation of 8.2 inches.
Measured 5.5 inches of storm total accumulation including a 2-hour period of heavy snowfall and limited visibility late in the afternoon on the 22nd.
Numerous WYDOT mesonet stations along Interstate 80 reported one-quarter mile visibility in falling and blowing snow with 45 to 55 mph wind gusts during this period, including Halleck Ridge (WY18) and Elk Mountain (WY19). Interstate 80 was closed between Laramie and Rawlins for an extended period of time until late on the 24th. CoCoRaHS observers near Elk Mountain reported a storm total snow accumulation of 14 to 18 icnhes.
WYDOT mesonet stations along Interstate 80 at Walcott Junction (WY14) and Sinclair (WY15) reported one-quarter mile visibility in falling and blowing snow with 35 to 50 mph wind gusts during this period. Interstate 80 was closed near Rawlins for an extended period of time until late on the 24th. Local emergency management reported local power outages along with numerous search and rescue operations to collect stranded motorists. COOP observer 1 mile north of Rawlins reported a storm total snowfall of 18 inches.
Emergency manager reported ongoing search and rescues for utility workers attempting to restore power to the area and for families trapped in their homes near the town of Medicine Bow due to snow drifts up to 14 feet high.
WYDOT webcams from Muddy Gap showed whiteout conditions due to falling and blowing snow for most of the day. Nearby WYDOT mesonet station Pathfinder (KPAT) along highway WY-220 reported one-quarter mile visibility with winds gusting around 45 mph during this time.
Numerous WYDOT mesonet stations along Interstate 80 between Laramie and Rawlins reported wind chills as low as 43 degrees below zero.
Numerous WYDOT mesonet stations along Interstate 80 between Laramie and Cheyenne reported wind chills as low as 41 degrees below zero.
WYDOT mesonet station Gun Barrel (KGUN) along Highway US-85 reported wind chills as low as 40 degrees below zero.
Laramie Airport ASOS station (KLAR) reported wind chills as low as 42 degrees below zero with a minimum temperature of 23 degrees below zero.
Saratoga Airport AWOS station (KSAA) reported wind chills as low as 42 degrees below zero with a minimum temperature of 22 degrees below zero.
Numerous WYDOT mesonet stations along Interstate 80 between Laramie and Cheyenne reported wind chills as low as 44 degrees below zero.
Cheyenne Airport ASOS station (KCYS) reported wind chills as low as 37 degrees below zero with a minimum temperature of 19 degrees below zero.
Douglas Airport ASOS station (KDGW) reported wind chills as low as 45 degrees below zero with a minimum temperature of 30 degrees below zero.
Wheatland Airport AWOS station at Phifer Airfield (KEAN) reported wind chills as low as 34 degrees below zero with a minimum temperature of 24 degrees below zero.
Torrington Airport ASOS station (KTOR) reported wind chills as low as 38 degrees below zero with a minimum temperature of 23 degrees below zero.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2023Every state in 2023This day in weather historyWarnings in Wyoming, February 2023
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: 1072312, 1072311, 1072309, 1072308, 1072313, 1072320, 1072310, 1072318, 1072319, 1072316, 1072315, 1072321, 1072304, 1072303, 1072307, 1072306, 1072347, 1072349, 1072350, 1072337, 1072345, 1072348, 1072333, 1072343, 1072344, 1072342.