textproduct: Western and Central Wyoming

KEY MESSAGES

- A weather system brings snow showers to western Wyoming tonight, with the highest totals occurring between about 10pm and 3am. Minor impacts due to snowfall and gusty winds are possible along Teton and Togwotee Passes.

- Gusty winds 30 to 50 mph occur along and east of the Divide after midnight, continuing through Tuesday. The strongest winds are expected between about 3am and 2pm and from South Pass to Casper.

- A quick-moving weather system continues light snow chances over western Wyoming Tuesday night.

UPDATE

Issued at 1233 PM MDT Mon Oct 26 2026

Overall, the weather system for tonight is still on track, with a few detail changes with the latest guidance. Starting with wind, the watches have been cancelled. Confidence is not quite high enough for widespread winds over 55 mph to occur. However, it's still going to be windy just ahead and behind the front, with fairly widespread gusts 30 to 50 mph along and east of the Divide. Wind prone locations, like along South Pass and Outer Drive in Casper, could still see stronger winds. The other aspect is snow. Overall, not any notable changes with forecasted amounts. Hi-res models are in good agreement on timing of snow showers occurring between about 10pm and 2am tonight. With a bit of CAPE, there will likely be a little convective element to the showers, meaning snowfall rates could be relatively high. Latest guidance suggests possibly 1 to 3 inches occurring over Teton and Togwotee Passes in about a 3-hour period.

DISCUSSION

Issued at 232 AM MDT Mon Oct 26 2026

I have to apologize for the forecast yesterday, the rain showers reached a bit further north than I or most of the guidance thought. However, most areas need rain so complaints were few. And, many areas will have an additional couple of chances of precipitation over the next week or so.

We still have a few light showers out there early this morning, but these should be gone by sunrise, which is getting rather late (after 7:30 am). All in all, today looks like a fairly low impact day as shortwave ridging should bring a mainly dry and somewhat warmer day to the area. We have a couple of small concerns. The first is that maybe the fog monster could come crawling out of his lair and bring some reduced visibility. He is still sleeping at this time, but we will see if he wakes up. The other will be some gusty wind developing in the favored Muddy Gap to Casper area, but nothing unusual through around midnight. There should be more sun today as well, and this should allow for temperatures to be a bit warmer than over the weekend.

The first weather maker, an area of low pressure now moving onshore in the Pacific Northwest, will be the first concern of the forecast. Concerns remain the same as yesterday, with a period of snow, potentially heavy in western Wyoming, and potential strong to high wind in areas east of the Divide. We will start with the snow. Snow should hold off until after sunset this evening. We also have decent model agreement in having the heaviest precipitation between 9 pm and 3 am tonight, when the trough axis and cold front move through the area. Snow levels will start fairly high, above 8500 feet, as 700 millibar temperatures are expected to be at 0 Celsius or above. These will quickly drop to around minus 4C to minus 6C, dropping snow levels to the valley floors. There will also be an approaching 100 knot jet streak, enhancing lift. The limiting factor will be the speed of the system, as the heaviest precipitation should only last at most six hours, possibly as few as three. This should limit amounts somewhat. Most areas should see at least a coating in the west. However, the area that has a greater than 1 out of 2 chance of 3 inches or more is largely restricted to areas above 9500 feet. As for areas with advisory level amounts (6 inches in the mountains), this is largely restricted to areas above 10,500 feet and in places like southwestern Yellowstone Park, where impacts would be minimal. So, we will not issue advisories at this time. However, there could be a period of a few hours later this evening when there could be a period of heavy snow and gusty wind that could make travel difficult, especially over the mountain passes. The steadiest snow should end by sunrise, with only a few leftover showers after sunrise Tuesday.

The other concern is strong to potentially high wind. It will be a decent setup for strong wind with an 100 to 110 knot jet streak moving across the area and a trough to help mix strong wind to the surface. There is also a decent area of 50 to 55 knot wind at 700 millibars in the favored southwest flow areas, mainly from Muddy Gap through Natrona County, with the strongest wind between 6 am and noon on Tuesday. Probabilistic guidance is still borderline though. There is a 1 in 2 chance of wind gusts past 55 mph in portions of the area. However, much of this area is over areas that have higher thresholds (65 mph for East Casper, 75 mph for the higher elevations). So, we will continue the Watch for now and let the day crew take one more look at it. Wind should decrease late Tuesday into Tuesday night as the low moves away and the pressure gradient decreases.

There is one more concern for Tuesday night, especially late, in the form of a trailing shortwave that would mainly impact southwestern Wyoming. There is not a ton of moisture with it. However, there will be some right rear quadrant jet energy to produce more lift. The current forecast may be too dry. This will be another quick system which should limit amounts but the potential for an inch or two of snow in places like Kemmerer, Farson, Pinedale or even Rock Springs later Tuesday night. Again, with the fast movement of the system, all precipitation should end by sunrise Wednesday.

Flat ridging should then bring mainly dry weather Wednesday through most of Friday. My gut feeling is that the forecast for Friday looks too wet. The next system in the form of a low moving in from the southwest will bring the next chance of showers for next weekend. There are still differences in the details, with some models showing a deep trough developing across the western United States and others showing the trough flatter and further north. So, details are still difficult to hash out at this time. Southwest flow should bring near to somewhat above normal temperatures through the end of the work week and possibly to Saturday as well.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 430 PM MDT Mon Oct 26 2026

Conditions will remain dry to start the TAF period with SKC skies over areas east of the Divide and the eastern half of Sweetwater County. A cold front will move from west to east across the forecast area, reaching the ID/WY border around 04Z/05Z. Precipitation will be widespread across the western mountains as the front tracks eastward, impacting KJAC, KBPI/KPNA and KCOD. Increased winds and marginal MVFR/VFR conditions will occur in a brief window of time due to the fast eastward progression of the front. Mountain obscurations will be widespread over the western mountains as well, becoming confined to northwestern portions by 18Z. Wind gusts around 30kt will occur at KCPR both ahead and behind the front. Similar winds with gusts up to 20kt will occur at KCOD after 17Z. Otherwise, winds at the remaining terminals will stay light (11kt or less) through the period. The highest winds will occur along the east slopes of the Wind River, Absaroka and Bighorn Mountains from 12Z onward. Clouds will scatter out across most areas through the morning, as drier air moves in behind the front. Clouds will increase again over areas west of the Divide toward the end of the TAF period as another weak storm system approaches the state.

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

RIW WATCHES/WARNINGS/ADVISORIES

None.