textproduct: Western and Central Wyoming

KEY MESSAGES

- Precipitation persists over western WY tonight through Tuesday with periods of moderate to heavy snowfall in the mountains and a mix of rain/snow in the lower elevations.

- Gusty winds across portions of central and southern WY with gusts of 35 to 45 mph possible at times through this evening.

- Besides winds locations east of the Divide look to see mostly dry and mild conditions prevail through the first half of the week.

UPDATE

Issued at 1150 AM MST Sun Jan 4 2026

Little has changed regarding the short term forecast with precipitation continuing across western WY and gusty winds in portions of central and southern WY. Temperatures have begun to rise slightly above freezing in parts of the western valleys. Jackson has seen a transition over to rain with temperatures to flirt with freezing through the remainder of the day. Temperatures will drop by the evening which should allow for some snow accumulation to occur overnight. Precipitation will be periodic with some periods of moderate to heavy precipitation likely at times overnight. Light showers will be possible across the lower elevations during the day Monday, while higher elevations will continue to see periods of moderate to heavy snowfall. Precipitation gradually decreases during the evening Monday with some showers possible into the morning hours Tuesday. Winds continue to decrease through the remainder of the afternoon and evening today. Some breezy winds will linger into the overnight with occasional gusts around 30 mph possible mainly around Casper. Otherwise, locations east of the Divide are expected to remain mostly dry with warm above normal temperatures prevailing through the first half of the week.

DISCUSSION

Issued at 108 AM MST Sun Jan 4 2026

Snow has started over western portions, with the expected shortwave reaching the Cowboy State as of 06Z Sunday. This wave will bring the first round of snow and subside sometime around sunrise and remain light through the rest of the morning. Snow will pick back up by early afternoon, becoming steady by the evening and continuing through the rest of the night. Snow will spread to southern Lincoln County, the Upper Green River Basin and Sweetwater County by this time as well, with minor snowfall accumulations. I-80 will be largely unaffected, except toward Continental Divide and Wamsutter which will have a 40% chance for a rain/snow mix late tonight. Expected snowfall amounts remain largely unchanged, with 8 to 16 inches in the western mountains through Monday morning and locally higher amounts of 18 to 24 inches in the Tetons/Gros Ventres and southwestern Yellowstone (the Pitchstone Plateau). Snow in the Jackson/Star Valleys will have limited accumulations, melting during the day today and having the best chances for accumulations tonight into Monday morning. All told, 1 to 3 inches is expected. Conversely, the upper end of the Green River Basin near Bondurant and Hoback Junction is expected to receive 4 to 6 inches.

The strong to high winds developed a bit earlier than expected over South Pass/Red Canyon, with 50 to 60 mph gusts occurring around 03Z/04Z (8pm/9pm Saturday) Sunday and have had gusts up to 80 mph as of 07Z. Gusts up to 50 mph are occurring in the Casper area, with the threat for 60+ mph gusts still in place through sunrise. At the same time, gusts up to 70 mph will be possible north of Cody on Hwy 120 near Clark between 13Z and 19Z. Windy conditions will develop across much of the CWA this afternoon, with gusts of 30 to 45 mph impacting the Wind Corridor (eastern Sweetwater County to southern Johnson County), southern Lincoln County and the higher elevations. These winds will decrease this evening, but remain focused from southern Lincoln County to southern Johnson County through the night.

Snow will continue over the western mountains Monday afternoon, as another shortwave moves over the area. The current advisories may need to be extended as a result. Southern portions could be impacted by snow showers in the afternoon as the wave reaches far western portions of the state. Brief reductions in visibility would be the biggest impact, as temperatures are expected to be in the upper 30s. Additionally, west to southwest winds with gusts of 30 to 45 mph will be widespread across western and southern portions, as well as the Wind Corridor, Monday afternoon. This would contribute to the hazard to visibilities from the snow showers.

The flow pattern will shift to the west-northwest Tuesday, as yet another shortwave moves over the Cowboy State. Snow be light over northwestern portions during the day and could lead to a persistent flow through the night and into Wednesday. A strong cold front will move through the area as early as Wednesday, bringing temperatures back to more seasonal levels. Model guidance is split between either Wednesday or Thursday and would place better chances on Thursday at this point. Chances for widespread precipitation are higher with this system, but amounts are looking to stay on the low end. Dry and cold conditions look to be in place by Saturday, gradually warming up on Sunday.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1003 PM MST Sun Jan 4 2026

West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals.

Fog, snow, and low clouds are settling into KBPI/KPNA currently, and will hold well into the day Monday. KJAC has the low cigs, but the precipitation has been patchy so far. This should also fill in overnight, with all three sites at LIFR for the morning hours. Cigs and vis will lift to MVFR at KJAC around 18Z, with slow improvement through the rest of the day. Precip will end faster at KBPI/KPNA, with better cigs by 20Z. KRKS will have a much lower probability of snowfall overnight, so have kept to PROB30 groupings for any precip.

East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals.

VFR conditions expected for most of the next 24 hours, with high cirrus pouring overhead. KLND may still see some brief light snow around sunrise Monday, but any impacts would be brief, and may stay confined closer to the mountains.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts.

RIW WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 11 AM MST Monday for WYZ001-012- 014-024.