textproduct: Western and Central Wyoming

KEY MESSAGES

- Dry with seasonal temperatures today. Low clouds and fog decreases through the morning.

- A weather system brings a period of snow to western Wyoming tonight, and strong to potentially high wind East of the Divide into early Tuesday afternoon. Minor impacts to Teton and Togwotee Passes are possible.

- Another fast moving system may bring some light snow to southwestern Wyoming Tuesday night.

- Mainly dry and somewhat warmer from Wednesday through most of Friday.

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 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 4 to minus 6, dropping snow levels to the valley floors. There will also be an approaching 100 knot jet streak, enhancing lift. The limiting factor will be 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 10500 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 millibar wind 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 workweek and possibly to Saturday as well.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 443 AM MDT Mon Oct 26 2026

Areas of low clouds will persist into the morning for portions of the area, with the highest likelihood in vicinity of KCPR, KBPI, KPNA and KRIW. At KRIW, areas of fog have formed and will be around from time to time through around 16Z with periods of IFR to LIFR conditions before it gradually burns off. Largely VFR conditions are then expected at all TAF sites from around 16Z Monday through 04Z Tuesday. Wind should remain under 11 knots at all terminals through 06Z tonight, with the exception of KCPR which will see a gusty wind develop this afternoon and persist through the night, with gusts over 30 knots likely (70 percent chance) after 08Z Tuesday.

A weather system will move into western Wyoming after 04Z tonight and bring a period of snow and rain changing to snow. The rain and snow will mainly impact KJAC, KPNA and KBPI between 05Z and 12Z, with the highest chance of IFR conditions (around 50 percent) in vicinity of KJAC. Mountain obscurations are expected during the time of this period of rain and snow.

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 Watch from late tonight through Tuesday afternoon for WYZ019-020.