Heavy snow occurred across extreme southeast Wyoming 17-18 January 2023.
Every event with a place to put it; 6 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.
Heavy snow occurred across extreme southeast Wyoming 17-18 January 2023.
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 Jan 17, 3:32 PM MST, 58 minutes earlier.
Area Forecast Discussion...CORRECTED
National Weather Service Cheyenne WY
332 PM MST Tue Jan 17 2023
.SHORT TERM...(Late this afternoon through Thursday night)
Issued at 315 PM MST Tue Jan 17 2023
Afternoon GOES-W IR/VIS imagery showed the primary upper level low
pressure center along the UT/AZ border. Copious Pacific moisture
was streaming north-northeast into WY/CO/NE. A surface low was
organizing across western CO, with a front trailing south into
western NM. Precipitation was increasing in coverage in advance of
the upper low from eastern UT to the I-25 corridor in CO. Skies
were mostly cloudy to cloudy, with low stratus and patchy fog
lingering over the northern NE Panhandle. Temperatures were 5 to
10 degrees cooler compared to Monday with readings in the mid 20s
to mid 30s. A weak surface trough along the Laramie Range separated
easterly winds from westerly winds.
The primary concerns with the next 24 to 48 hours will be snow
accumulations tonight through Wednesday with the winter storm and
gusty winds on the backside of the exiting upper low.
Model ensembles (ala SREF plumes) and associated QPF/snow totals
have increased since the 06Z WPC guidance, and trended slightly
northward with the heavier snow totals. The upper low tracks east
across the Four Corners through this evening, and through
southeast CO/western KS Wednesday morning. This will strengthen
the surface low pressure system over eastern CO overnight. The GFS
has slowed the progress of the low with the ECMWF a bit faster.
Favoring the HRRR with the overall placement of the heavier
snowfall, which has trended slightly more north. At this time,
upwards of 8 to 12 inches with locally higher amounts is expected
over the southern half of the NE Panhandle into far southeast WY.
Along the I-25 corridor from south of Douglas to the CO border, 4
to 8 inches is expected. Winter Storm Warnings were expanded west
from Cheyenne to the I-80 Summit. Winter Weather Advisories were
issued for the Laramie Valley (2 to 5 inches), and North Laramie,
Snowy and Sierra Madre Ranges (5 to 10 inches). No changes were
made to the time period of the winter weather headlines (5 PM this
afternoon to 5 PM Wednesday). The period of most impactful winter
conditions is late this evening through late Wednesday morning.
Snowfall rates 1-2 inches an hour are possible in the warned areas
where banding develops. The snow will begin tapering off from
west to east Wednesday afternoon. Despite the low visibility in
falling snow and hazardous travel, winds are not forecast to
increase until Wednesday afternoon, and especially Wednesday night
and Thursday morning with stronger low level gradients on the
backside of the departing upper low. Blowing/drifting snow will
become a concern at that time. In fact, the in-house random forest
high wind rise to near 60 percent between 09Z and 12Z Thursday at
Arlington and the I-80 Summit. Probabilities are lower at Buford
and Bordeaux. Peak gusts of 45-55 MPH are possible for these wind-
prone areas.
High temperatures Wednesday and Thursday will be below normal with
mid 20s to mid 30s. After lows tonight in the teens and 20s, lows
Wednesday night and Thursday night will drop into the upper
single digits and teens.
.LONG TERM...(Friday through Tuesday)
Issued at 315 PM MST Tue Jan 17 2023
A change in the large scale weather pattern is expected for the long
term period. The parade of Pacific troughs will come to an end, and
transition to more north to northwest flow. We still expect regular
shortwaves to impact the area, but these systems will likely be
colder and drier than the pattern since late December.
The first system will be a fairly vigorous but moisture starved upper
level low diving down from the Pacific northwest from Thursday into
Friday. A ridge will start to build in behind just off the West
Coast, which will close the door to the abundant Pacific moisture
most systems have tapped into for the last several weeks. The
upper level low will track well into the desert Southwest, and is
likely to be too far south for significant impacts to our area.
The ECMWF and its ensemble has minimal precipitation for our area,
while the GFS/GEFS brings some light precip to the I-80 corridor.
Even in the higher end scenario, doesn't look like more than a
dusting to an inch or so. Kept PoPs in the 15-25% range along the
I-80 corridor to have the mention of snow in the forecast, but
this looks fairly minor. Unfortunately, it will also bring a
little dose of arctic air. Models are in fairly good agreement on
700-mb temperatures dropping to around -12C behind this system.
This supports a cold day on Friday, with highs struggling to get
out of the 20s for many areas. Clouds will keep things cool on
Friday, but then clear out Friday night and allow temps to dive
further. Single digits and perhaps a few subzero readings are
possible early Saturday.
Transient ridging passes through on Saturday into early Sunday, so
should see temperatures moderate towards near/slightly below normal.
Models diverge somewhat on Sunday through the early part of next
week, mainly regarding the timing and intensity of the next trough.
The ECMWF depicts a faster, colder system with less precip, blowing
through fairly quickly on Sunday and leaving quite cold air in its
wake for Sunday into Monday. The GFS has a slower, warmer system
passing through mainly on Monday. Due to timing uncertainty, kept a
longer period of PoPs in the 20-40% range (slightly lower than NBM)
from Sunday through early Tuesday. Overall, the forecast does not
include any significant changes from previous updates.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1019 AM MST Tue Jan 17 2023
Flight conditions will deteriorate close to 00Z for the SE WY terminals
as VFR transitions to MVFR. Between 00Z and 12Z there will continue
to be a shift as -SHSN move into the region and IFR/LIFR/MVFR
fluctuations are likely for SE WY terminals. Winds are expected to
be 15 knots or less through 12Z Wednesday, with gusts beginning to
pick up closer to the 15Z-18Z timeframe for SE WY terminals.
NE Panhandle will see a larger window of -SHSN impacting the area
beginning later this afternoon and evening through Wednesday. Low
CIGs for KAIA and KCDR will remain present between 18Z-0Z today
resulting in continued IFR/LIFR/MVFR fluctuations. KBFF and KSNY
will see CIGs decreasing through 18Z-00Z today, and VIS will quickly
follow this trend after 00Z. All NE Panhandle terminals can expect
IFR/LIFR overnight due to persistent -SHSN. MVFR can be expected
to be present after 18Z Wednesday for the NE Panhandle terminals.
Wind gusts are expected to be at or below 15 knots through the
forecast period.
&&
.FIRE WEATHER...
Issued at 315 PM MST Tue Jan 17 2023
No fire weather concerns are expected due to widespread snow Tuesday
night and Wednesday. Moderate to heavy snow is expected across portions
of Southeast Wyoming and the Nebraska Panhandle. Gusty northwest winds
will produce some blowing snow Wednesday night and Thursday. Temperatures
will remain below normal through the weekend.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory from 5 PM this afternoon to 5 PM MST
Wednesday for WYZ101>103-106>108-110-112-114-115.
Winter Storm Warning from 5 PM this afternoon to 5 PM MST
Wednesday for WYZ116>119.
NE...Winter Weather Advisory from 5 PM this afternoon to 5 PM MST
Wednesday for NEZ002-095-096.
Winter Storm Warning from 5 PM this afternoon to 5 PM MST
Wednesday for NEZ003-019>021-054-055.
&&
SHORT TERM...MAJ
LONG TERM...MN
AVIATION...BW
FIRE WEATHER...MAJHazardous Weather Outlook...UPDATED National Weather Service Cheyenne WY 136 PM MST Tue Jan 17 2023 WYZ104-105-109-111-113-182045- Ferris/Seminoe/Shirley Mountains-Shirley Basin- Central Carbon County-Southwest Carbon County- Upper North Platte River Basin- 136 PM MST Tue Jan 17 2023 This hazardous weather outlook is for portions of south central Wyoming. .DAY ONE...THIS AFTERNOON AND TONIGHT Snow will develop this afternoon and continue tonight. Periods of moderate snow are expected. Accumulations will range from 2 to 4 inches by Wednesday morning. Winter Weather Advisories are in effect until 5 PM MST Wednesday. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY Snow will continue Wednesday morning, tapering off from west to east in the afternoon. Additional accumulations of 1 to 2 inches are expected. .Spotter information statement... Spotter activation will not be required. WYZ112-114-115-182045- Sierra Madre Range-Snowy Range-Laramie Valley- 136 PM MST Tue Jan 17 2023 This hazardous weather outlook is for portions of south central Wyoming and southeast Wyoming. .DAY ONE...THIS AFTERNOON AND TONIGHT Snow will develop this afternoon and continue tonight. Periods of moderate snow are expected. Accumulations will range from 2 to 5 mountains, to 1 to 3 inches Laramie Valley by Wednesday morning. Winter Weather Advisories are in effect until 5 PM MST Wednesday. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY Snow will continue Wednesday morning, tapering off from west to east in the afternoon. Additional accumulations of 2 to 5 inches are expected for the mountains and 1 to 2 inches for the Laramie Valley. .Spotter information statement... Spotter activation will not be required. NEZ003-019>021-054-055-WYZ116>119-182045- Box Butte County-Scotts Bluff County-Banner County-Morrill County- Kimball County-Cheyenne County-South Laramie Range- South Laramie Range Foothills-Central Laramie County- East Laramie County- 136 PM MST Tue Jan 17 2023 This hazardous weather outlook is for portions of Panhandle Nebraska and southeast Wyoming. .DAY ONE...THIS AFTERNOON AND TONIGHT Snow will develop late this afternoon and continue tonight. Periods of moderate to heavy snow are expected. Accumulations will range from 4 to 8 inches by Wednesday morning. Winter Storm Warnings are in effect until 5 PM MST Wednesday. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY Snow will continue Wednesday morning, tapering off from west to east in the afternoon. Additional accumulations of 2 to 5 inches are expected. .Spotter information statement... Spotter activation will not be required. NEZ002-095-096-WYZ101>103-106>108-110-182045- Dawes County-Northern Sioux County-Southern Sioux County- Converse County Lower Elevations-Niobrara County- North Laramie Range- Central Laramie Range and Southwest Platte County- East Platte County-Goshen County-North Snowy Range Foothills- 136 PM MST Tue Jan 17 2023 This hazardous weather outlook is for portions of Panhandle Nebraska...east central Wyoming...south central Wyoming and southeast Wyoming. .DAY ONE...THIS AFTERNOON AND TONIGHT Snow will develop late this afternoon and continue tonight. Periods of moderate snow are expected. Accumulations will range from 2 to 4 inches by Wednesday morning. Winter Weather Advisories are in effect until 5 PM MST Wednesday. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY Snow will continue Wednesday morning, tapering off from west to east in the afternoon. Additional accumulations of 1 to 2 inches are expected. .Spotter information statement... Spotter activation will not be required.
The national radar mosaic for the moment the first event began.
6 heavy snow. Local standard time, as filed.
Crow Creek SNOTEL estimated 6 inches at 5AM on the 18th. Peak snowfall 9 inches.
Spotter reported 8 inches of snow that fell mainly before 11 AM on the 18th.
NWS employee 10.7 miles north of Cheyenne reported 6.5 inches. Highest total reported was 10 inches at 5 miles south southwest of Hillsdale.
Report received via Facebook of 8 inches in Pine Bluffs.
Public report received via Facebook of 7 inches of snowfall in Torrington Wyoming. Peak snow report 11 inches in Veteran Wyoming at 130 PM on the 18th.
Report received via Twitter of 9.0 inches of snow at 930AM. Peak snowfall report of 10.3 inches 8 miles southwest of Wheatland at 245PM on the 18th.
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, January 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: 1065907, 1065908, 1065909, 1065910, 1065905, 1065906.