textproduct: Western and Central Wyoming

KEY MESSAGES

- Strong to high winds continue tonight for much of the area. Travel impacts remain possible through the night.

- Another weather system brings gusty winds and heavy western mountain snow Thursday afternoon through Friday.

UPDATE

Issued at 1206 PM MST Wed Dec 17 2025

Strong winds have been observed already across the area, with High Wind Warnings in effect for the area through at least this evening. Have extended the High Wind Warning for the Buffalo area through early tomorrow morning for the prolonged threat of downsloping mountain winds, and a northerly wind shift which favors stronger winds there. Winds begin to decrease late afternoon and into the evening, though remains gusty through tonight.

For the next system, which is quick to follow, snow chances begin over the western mountains as early as about sunrise, with the main push arriving early Thursday afternoon. Periods of heavy, wet snow are expected over the western mountains through Friday. To avoid any confusion, have held off any winter highlights (wind or snow) with this next system so the current highlights can expire later today or tonight.

DISCUSSION

Issued at 258 AM MST Wed Dec 17 2025

Record breaking warmth continued across the Cowboy State on Monday. If you were to look at the high temperatures across many locations east of the Divide over the past two weeks, you would think its currently mid October. High temperatures have been nearly 20 to 30 degrees above normal for a prolonged period and that continues today. Temperatures once again will be very mild with highs in the mid 50s east of the Divide and low to mid 40s west of the Divide. Frankly, we may see some locations east of the Divide near 60 once again, especially once winds pick up and mix down during the afternoon today.

Temperatures while being well above normal are going to be the least concern today. The next disturbance will bring widespread impactful weather to the state starting this morning. The main catalyst is a potent upper-level low currently developing over the PACNW. This low will make its way east remaining well to the north of the state. However, a potent jet streak associated with this disturbance will make its way south bringing with it widespread strong gusty winds. Models have and continue to remain very bullish with 700mb winds of 60 to 80 knots across much of the region. These winds start early Wednesday morning and intensify through the mid to late morning into the afternoon. Surface wind gusts of 60 mph will be common (60-80%) over most of the CWA with stronger gusts possible in wind prone areas. Downsloping across eastern slopes may create stronger gusts exceeding 60 mph in some locations, isolated gusts nearing 70 mph cannot be ruled out at times. Favorable locations that may possibly see these wind gusts of 70 mph or more include Cody, Lander, and Buffalo with probabilistic chances ranging from 40 to 70%. Winds look to gradually decrease over much of the state after sunset. However, there is some exceptions to this and that looks to be along the eastern slopes of the Absarokas and Bighorns. Hi-res models have picked up on a linger push of strong winds around 60 mph moving through these areas during the early morning hours Thursday. As a result of this High Wind Warnings have been extended to 5 am MST on Thursday. No further changes have been made to previous High Wind Warnings.

The other aspect of this system will be periods of heavy snowfall across the higher elevations of western WY mountains. Precipitation will continue to spread in coverage early this morning. Strengthening westerly 700mb winds will enhance orographic dynamics during the mid to late morning and early afternoon Wednesday. This period will likely see the heaviest snowfall for western mountains with snowfall rates of 1 to even 2 inches possible. The heaviest snow is expected to be limited to the highest elevations above 8,500 feet due to warm temperatures. A nearing cold front and its passage will begin to cutoff the heaviest precipitation over western WY. The timing looks to be in the late afternoon on Wednesday with it gradually spreading over central WY by the late evening Wednesday into the early morning hours Thursday. Storm total snowfall amounts have remained fairly consistent over the past 24 hours with not much change to note. The higher elevations above 8,500 feet across the Tetons, Gros Ventre and Wind River Ranges currently look to see anywhere from 6 to 12 inches. Higher peaks may see amounts nearing 14 to 18 inches. Other locations such as the western Absarokas, the Salt River/Wyoming, and higher elevations of YNP can see amounts of 6 to 12 inches. Locally higher amounts of 8 to 14 inches are possible over southwestern YNP specifically Pitchstone Plateau. Warm temperatures will greatly limit snow accumulations across lower elevations and western valleys. Storm total amounts for these areas are low ranging from a wet slushy coating to an inch or two. No changes have been made to winter related highlights and as a result Winter Storm Warnings remain in place for western mountains through late Wednesday evening.

Precipitation is forecast to remain mostly confined to portions of western WY and higher elevation mountains. However, some showers will be possible ahead of the cold fronts passage. The timing for these showers east of the Divide looks to be around late morning through the early afternoon. Temperatures will be too warm for any snowfall so if any precipitation does fall east of the Divide it would likely be in the form of rain. Overall, only light precipitation looks possible east of the Divide and will be isolated. There is one caveat though and that is the small possibility for a very isolated thunderstorm. This will also be possible west of the Divide with the chance for a few strikes of lightning and rumbles of thunder not completely off the table.

Thursday will see temperatures that are cooler but still above normal. While it may not feel like October on Thursday it still will not be feeling like December. Highs are forecast to range in the low 40s east of the Divide and mid to upper 30s west of the Divide. So instead of December temperatures will be more like November, which is a slight improvement towards normalcy that says a lot about how the month has gone so far. Otherwise, another disturbance takes aim at the state with very similar impacts as this current disturbance. Wet heavy snow looks increasingly likely for western mountains with widespread strong gusty winds returning to the area as well. Currently the timing for precipitation would be Thursday afternoon with winds gradually increasing late Thursday into Friday. The greatest impacts are likely to be limited to the western mountains and passes due to the combination of strong winds and heavy snow. Winds thankfully do not look as intense but some strong gusty winds do look possible. Winter related highlights may need to be issued due to increasing confidence in snow amounts.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1009 PM MST Wed Dec 17 2025

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

Wind will generally be on the decline through the overnight hours as upper support wanes. KRKS will hold on to stronger gusts the longest, up to 35 knots until around 13Z when gusts drop to 20 knots. Otherwise, VFR conditions are expected at terminals tonight. The next system begins pushing into western Wyoming late Thursday morning. KJAC will see MVFR impacts around 20Z, with IFR visibility expected by 23Z. Confidence is lower for this to impact KBPI and have a PROB30 group there for now. KPNA is expected to see IFR visibility late in the period.

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

Stronger winds linger east of the Divide late this evening. These too will generally decrease through the night, with KCPR and KRIW most favored to keep gusts around or over 40 knots through 10-12Z. Wind will increase again after 18Z at most terminals as the next system approaches, though gusts are expected to stay under 40 knots. Otherwise, VFR conditions are expected with scattered to broken high ceilings.

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

High Wind Warning until 5 AM MST Thursday for WYZ003-008>010.