textproduct: Western and Central Wyoming

KEY MESSAGES

- One more warm day with locally breezy conditions. A few showers and thunderstorms will be around in locations similar to yesterday.

- And approaching weather system will bring a good chance of showers to much of the area from later tonight into the weekend, with most rain across northern and western Wyoming.

- Accumulating snow is likely this weekend in the mountains, especially above 9500 feet.

DISCUSSION

Issued at 230 AM MDT Fri May 29 2026

Meteorology is one of the physical and mathematical sciences. And the weather is basically governed by complex mathematical equations (some I would like to forget, I still have nightmares about dynamics class 28 years after I finally passed it). One of the most common is the sine wave, most often used with Rossby Waves. The weather often runs like a wave pattern with crests and troughs of different parameters. And we are currently in a crest and trough of one right now. On Thursday, we had the crest in temperatures, with a trough in coverage of precipitation. Starting today and especially going into this weekend, this is going to begin flipping.

The main reason is the cut off low that has been spinning across California and Nevada for the past few days. It will finally get a nudge and will begin heading northeastward toward Wyoming today. Moisture will begin to head back into the area, although it will take a while to deepen. There will be a few more showers and storms around today. However, most guidance shows it will be later show with some sticking around into the evening. With the flow turning southeast, the most impacted areas will be similar to yesterday, the favored upslope areas like around the east sloes of the Absarokas and the Bighorns as well as Natrona and Johnson County where moisture will build the fastest. Even here, the chance of a shower or storm is probably no more than 1 out of 3. It will be another very warm day, but with increasing cloud cover probably a few degrees cooler than yesterday. And there will again be a bit of a gusty breeze, especially in southwest Wyoming, where, combined with still low humidity, may bring elevated fire weather this afternoon.

Precipitation will really increase later tonight and into Saturday as the upper level low finally moves into Wyoming. Most guidance shows the same general pattern as yesterday, with a northwest to southeast gradient of QPF with the highest amounts in the west and north. Areas further to the east will likely having more of a southwest downsloping flow that will keep the precipitation more showery. Every location will have a chance of rain though. As for how much, we will take a look at the NBA ensembles for this. At this point, it is fairly similar to yesterday, with a greater than 1 in 2 chance of a quarter of an inch of QPF or more mainly north and west of a Evanston to Riverton to Kaycee line. The highest amounts still look to be in northwestern Wyoming and near the Bighorns though, with a greater than 1 in 2 chance of an inch of QPF or more. The Weather Prediction Center continues to have a marginal risk of excessive rainfall across northern Wyoming on both Saturday and Sunday. It has been fairly dry, so there is room in the soil. But it is something to keep in mind. Saturday continues to look like the wettest day. However, the low will likely slow down somewhat and stall over Montana. This will keep unsettled weather over parts of the area, with northern Wyoming the most impacted. How far south it can stay this way is in question, since there are differences in guidance as to when the low will lift out of the area.

Needless to say, it will be much cooler with the cloud cover and showers. This is especially so on the western side of the low where flow will be northerly. A place like Jackson may stay below 55 all weekend. And this brings us to another part of the system, the chance of snow. Yes any visitors to the Cowboy State, it can snow here any month of the year. Now, it will not accumulate in the lower elevations, and travel should not be impacted much as it has been very warm and the high sun angle would melt snow on roads. However, we do have a decent chance of some accumulating snow in the mountains. Some models drop the 700 millibar temperatures as low as minus 1, which would lower snow levels to 8000 feet. We still think this is too low, it would likely be closer to 9000 feet. Ares above 9500 feet in the western mountains have a greater than 1 in 2 chance of an inch or snow, and this includes Togwotee Pass. Some of the higher elevations of the Tetons and Wind Rivers could see 6 inches or more of snow this weekend. So if you are recreating in the mountains, prepare for a cold and wet weekend. You will also likely see some snow if you are driving over Togwotee Pass.

Early next week is in questions as well. Some guidance lingers the low close enough for some showers to linger into Monday, other favor flow turning more to the west-southwest for a warmer and drier pattern. For most of the next week, the consensus seems to be for warm but not hot weather and a couple of chances of mainly diurnal showers and thunderstorm as shortwaves moving through the largely zonal flow.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1145 AM MDT Fri May 29 2026

VFR flight conditions are expected through 04Z Saturday for most terminals. This afternoon, winds are forecast to generally be in the 10kt to 15kt range, with gusts of 18kts to 28kts. There is a 30 percent chance of isolated thunderstorms from 20Z to 24Z today at KCPR and KCOD. Lingering showers are possible (15 percent chance) around KCPR after 24Z. Clouds will gradually increase from the south through the afternoon and evening ahead of an approaching weather system.

The weather system will approach from the south and first impact KRKS by 08Z Saturday. However, rain showers could begin as early as 04Z at KRKS. Rain showers spread to all other terminals between 07Z and 12Z with associated MVFR to IFR flight conditions. Rain is forecast to persist through 18Z Saturday at KJAC, KRKS, and KCOD. However, MVFR to IFR clouds and reduced visibilities are expected at all terminals once the bulk of the overnight rain diminishes. KCPR and KWRL are the only terminals forecast to be VFR through 18Z Saturday, with a 10 to 20 percent chance of MVFR flight conditions.

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.