textproduct: Western and Central Wyoming

KEY MESSAGES

- Winds have decreased across the area heading towards sunset with increasing mid level levels from the west as light showers push in over the Tetons into Jackson Hole.

- Another weather system brings rain and snow showers tonight, from Lincoln County to Johnson County. Light snow accumulation is possible (a 1 in 2 chance in the lower elevations) in the mountains and Jackson Valley.

- The next chance of showers arrives this weekend, with the potential of a more substantial system Sunday night into Monday and Tuesday.

UPDATE

Issued at 1054 AM MDT Tue Oct 27 2026

Conditions will remain dry through the rest of the day. The cold front quickly exited the CWA by sunrise this morning, with several areas receiving at least 0.01" of precipitation. Western portions received the highest amounts as expected, ranging from 0.10" to 0.30" and falling in the form of snow. West to southwest wind gusts of 30 to 40 mph will impact most areas this afternoon as the stronger winds aloft mix down to the surface. Winds will quickly decrease by 00Z (6pm). Showers will return over western portions by 06Z (midnight), as another cold front moves over the area from the west. Initial snow levels will be around 7000/7500ft so most of the precipitation is expected to stay as rain. The exception will be northwestern portions, including the Jackson Valley, where trace amounts are expected and 1-2" occur in the mountains. Precipitation will be along and north of a Kemmerer to Kaycee line, with most of this staying within a 30 mile radius of this line. Brief wind gusts up to 30 mph will be possible with the showers as well. Precipitation will end across the area by 12Z Wednesday as the cold front moves over the High Plains. Similar conditions from today then return by 18Z Wednesday with mostly clear skies across the area and west to southwest winds gusting 25 to 35 mph from southern Lincoln County to Casper as well as over the mountains.

DISCUSSION

Issued at 204 AM MDT Tue Oct 27 2026

So far, the forecast is working out fairly well. An area of rain and snow associated with the front and trough is working its way across western Wyoming. It is moving quite quickly and other than a few orographic showers in the northwestern mountains, should be out of the area by sunrise with a majority of the area dry for most of the day. Any snowfall amounts should remain sub-advisory, but some of the mountain passes could be slick into the morning before the snow melts off after sunrise. Our attention then turns to strong to potentially high wind. This will be mainly in the wind prone areas like around South Pass and from Muddy Gap northeastward through Casper.

There are some factors for it. We will have an 100 knot jet streak over the area today. Some models also show wind at 700 millibar millibars around 50 knots, especially through around 2 pm when there will be some decrease. There are some factors against it though. Most MOS guidance shows sustained winds at the Casper Airport only around 22 to 26 knots. I would like to see 30 knots to have more confidence for high wind. Next, we dive into the wonderful world of ensemble and probabilistic guidance. The National Blend of Models ensemble gives a greater than 1 in 2 chance of wind gusts over 30 mph across most of the area. However, for high wind we are interested in wind gusts over 55 mph. The main area with the strongest wind is over the higher elevations of Casper Mountain and the Green and Rattlesnake Ranges, where criteria is 75 mph gusts. There is an area on the south side of Casper that has a greater than 1 in 2 chance of gusts over 55 mph. However, criteria is higher here, gusts have to be over 65 mph. And chances of this are less than 1 out of 4. There could be an isolated high wind gust in places like Wyoming Boulevard on the South Side of Casper and along Hat Six Road, but this would be the exception and not the rule. So, we chose not to issue a High Wind Warning at this time. Wind should decrease later this afternoon as the system moves away and the pressure gradient begins to relax.

A second shortwave will approach the area on Tuesday night and bring another round of showers. This one is similar to this one in that 1) it will have some upper level dynamics to work with in the form of the right rear quadrant of a jet streak and 2) it will be a fast moving system, with most of the precipitation falling in a 6 to 9 hour period, most likely from 9 pm until around sunrise Wednesday. I am still concerned the current forecast may be a bit underdone on QPF amounts, especially in southwestern Wyoming. I could see an inch or two of snow in places like Kemmerer, Farson and even Big Piney and Pinedale with a bit more in the Salt and Wyoming Ranges and the western Wind River Range if banding sets up right. The only location with a greater than 1 in 2 chance of 4 inches or more is the highest elevations of the Wind River Range though, so no highlights will be issued. A few showers are possible east of the Divide, but the chance is generally less than 1 out of 3 and any amounts should be rather light.

Wednesday and Thursday look more tranquil as ridging builds over the area and brings dry conditions and above normal temperatures. The next concern shifts to a potential weekend system that could bring the next round of rain and / or snow. There has been somewhat in slowing of the progress of the system, so Friday may end up being mild and dry as well, especially east of the Divide. Most of the weekend details are still uncertain. The best chance of showers would be across western mountains through most of Sunday, but there is a large spread in guidance as to how numerous showers would be. However, Sunday night into Monday are starting to look interesting. A closed low may pass near or just south of Wyoming and with north flow into the area, it may be cold enough for the first accumulating snow in many of the lower elevations east of the Divide. Now, it is still a week out and a lot can change, but it is something to watch as we head later in the week and into the weekend.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 352 PM MDT Tue Oct 27 2026

Terminals with breezy afternoon winds are forecast to diminish by 00Z Wednesday. A cold front is on track to trek west to east across Wyoming in the 01Z to 12Z timeframe, bringing chances of light snow or a rain/snow mix and breezy winds to a few terminals. KJAC, KRIW, and KLND each have a 30 percent chance of snow or a rain/snow mix. Confidence is highest in prevailing snow showers at KPNA and KBPI overnight with associated MVFR to IFR flight conditions. All other terminals have a 10 to 20 percent chance of seeing precipitation with the front, so there is no mention in TAF at this time. IFR to MVFR flight conditions from fog is forecast after snow ends at KPNA and KBPI on Wednesday morning. Should precipitation occur at KJAC, KRIW, and KLND, the chance of reduced flight conditions from fog increases substantially. Given the low chances for fog at these three terminals, there is no mention in TAF at this time. Mountain obscurations will be common overnight and Wednesday morning.

Breezy winds return to KCPR and KCOD after 16Z Wednesday, with frequent gusts in the 18kt to 25kt range. Winds at all other terminals are forecast to be 12kts or less.

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

None.