textproduct: Western and Central Wyoming

KEY MESSAGES

- Isolated virga showers continue through tonight, with little to no rain reaching the ground.

- Shower chances increase Sunday afternoon through late Monday, with the more numerous showers on Monday. These chances (40% to 90%) are greatest across western and southern Wyoming.

- Rainfall amounts look modest at best for Sunday through Monday, mostly focused in western Wyoming. Up to an inch or two of snowfall is possible for the highest peaks of the Wind River Range.

- Warm and largely dry weather is forecast Tuesday through at least Friday.

UPDATE

Issued at 1049 AM MDT Sat Sep 26 2026

The forecast is largely on track this afternoon with a cold front pushing into northwest Wyoming and stalling. The pressure gradient will tighten with the front and result in gusty winds across much of the area. West to southwest gusts of 20 to 30 mph are expected for low elevations and gusts of 30 to 40 mph for higher elevations. The only change made this afternoon is the addition of low virga shower or light rain chances (up to 20%) across from Rock Springs to Casper. There is just enough mid-level moisture and vorticity aloft that could support this virga or a light rain from 6PM through 2AM. Additionally, a few light rain showers are possible across northern Wyoming around sunrise on Sunday. The gusty winds begin diminishing after sunset with light winds overnight. The Sunday through early Tuesday weather system is still expected to bring cooler temperatures and shower and thunderstorm chances to most.

DISCUSSION

Issued at 136 AM MDT Sat Sep 26 2026

One of my interests outside of meteorology is also something involved with looking at the sky. As I was driving into work this evening listening to classic rock (because I'm old), I heard a song that fits with tonight, Harvest Moon by Neil Young. It looked beautiful when I was driving in. Much of the area, not all but a decent amount, will be mostly clear through sunrise so I highly suggest going out and taking a look if you can.

Otherwise, things look relatively tranquil today. A weak cold front will approach from the north and this will bring some breezy conditions to some locations. And, there could be just enough mid level moisture for an isolated shower mainly in and near the mountains. The chance is now more than 1 in 10 and chances were added mainly for fire weather purposes. Most locations will see nothing and remain dry through at least Sunday morning. It will also be a warm day today, with high temperatures rising into the 80s across the warmer spots like Worland and Thermopolis and possibly Casper. As for potential fire weather issues, relative humidity should remain above critical levels. However, with values dropping to around 20 percent, locally elevated fire weather is possible in the breezier locations for a time this afternoon.

The next chance of rain moves in Sunday afternoon into Monday as some moisture moves into the area, with an upper level low driving some moisture from Hurricane Polo off of the Mexican coast. This, along with some upper level divergence and the front being in the area. This does not look like a big rainfall event though. This mornings model runs have come in somewhat drier, keeping the bulk of the moisture to the south of Wyoming. Much of the southern and western portions of the area still have a greater than 1 in 2 chance of over a tenth of an inch of rain, although this would fall over a greater than 1 day period. Chances of greater than a quarter of an inch of rain greater than 2 out of 5 are largely limited to the mountains and possibly the far southern portions of the area. And, we also have to talk about a bit of snow. There is not a ton of cold air with this system, with 700 millibar temperatures only falling to around 4 Celsius, which would put snow levels around 10000 feet. There will likely be some snow in the air. Accumulations would be light though. The NBM ensemble shows the only area with a greater than 1 in 2 chance of an inch or more to be in the Wind River Range, largely above 11500 feet with no impacts to travel corridors. Most of the showers should end by sunrise on Tuesday.

Following that, largely tranquil conditions should move back into the area for most of the period as ridging builds over the Northern Rockies. That means another fairly lengthy period of above normal temperatures and little chance of precipitation. We will will have to keep an eye to the south though. It looks quite wet down there as an upper level low moving from California combines with the remnants of Hurricane Polo to bring some soaking rain and possible problems with flooding. Almost all guidance keeps this moisture to the south and east of western and central Wyoming. However, upper level lows and tropical systems are fickle so we will continue to watch this. Looking way out to next weekend, we may really have a taste of fall as one of the first Canadian cold fronts may drop southward into Wyoming, bringing some much cooler temperatures. With the continental origin of the system, moisture looks limited though. It is still a week out so a lot can change, but we may finally have a decent taste of mid autumn Saturday or Sunday.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 345 PM MDT Sat Sep 26 2026

Conditions will remain VFR through the TAF period. Clouds will continue over western portions this evening, with lee-enhanced clouds developing off the east slopes of the Absaroka Mountains. Scattered clouds will continue across the area through the overnight hours, with SCT-BKN FL120-250 in place by 12Z. Wind gusts of 20 to 25kt will quickly decrease by 01Z, staying light (11kt or less) through 18Z Sunday. Wind gusts up to 20kt will return across areas west of the Divide between 19Z and 21Z.

There is less than a 20% chance for light showers to move northward over portions of Sweetwater County between 00Z and 04Z. Have left out any mention in the KRKS forecast due to the low confidence and high likelihood of little to no impacts. Another wave of light showers looks to move over the central basins between 11Z and 14Z, with little to no impacts expected again. There is a 20-30% chance for showers over southern portions of the forecast area after 21Z, pushing northward into the Wind River Basin and Natrona County by the end of the forecast period. These showers are not expected to impact KRKS, KLND or KRIW at this time.

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.