textproduct: Western and Central Wyoming

KEY MESSAGES

- A warm day is in store with highs ranging from the 60s to low 80s. There is a very low chance (10% to 15%) of a virga shower in and near the mountains.

- 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.

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

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 approaching 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. And it will be a warm day, 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 or rain, although this would fall over a greater than 1 day period. Chances of greater than a quarter of an inch or 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 and eye to the south though. It looks quite wet down there as an upper level low moving from the 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 /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 403 AM MDT Sat Sep 26 2026

VFR conditions will dominate through 12Z Sunday. A weak cold front moving into northern Wyoming will bring some gusty breezes to most terminals, with gusts to 18 to 25 knots possible mainly between 20Z Saturday and 02Z when wind will decrease as the atmosphere decouples. A stray shower can't be ruled out in and near the mountains but the chance is 10 percent or less and any shower would likely be virga.

RIW WATCHES/WARNINGS/ADVISORIES

None.