textproduct: Western and Central Wyoming

KEY MESSAGES

- Any showers ending early, then a somewhat warmer and mainly dry day today with more sunshine.

- An approaching weather system will bring a period of snow to western Wyoming tonight, and strong to potentially high wind East of the Divide on Tuesday.

- Another fast moving system may bring some snow to southwestern Wyoming later 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 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 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 to 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 should bring near to somewhat above normal temperatures through the end of the workweek and possibly to Saturday as well.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 948 PM MDT Sun Oct 25 2026

A weakening weather system will continue to slide through the area tonight exiting Monday morning. There will be very isolated showers tonight, with no impacts expected. There will be areas of low clouds in the area tonight into Monday morning. The best chance for MVFR to IFR CIGS will be at KCPR through Monday morning. There is a low chance (15%) of patchy fog and low clouds at KJAC, KBPI, and KPNA Monday morning.

Wind will remain below 10 knots through the TAF period with the exception of KCPR where wind will be 10-15 knots with gusts up to 20 knots Monday afternoon. Periods of mountain obscuration will occur through Monday morning. The next weather system will push into western portions of the area near the end of the TAF period. By 05Z/Tues conditions should drop to MVFR at KJAC due to a band of snow/rain moving into western Wyoming.

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.