textproduct: Western and Central Wyoming

KEY MESSAGES

- Showers continue today, with the greatest coverage across western Wyoming. Showers shift to southern and central Wyoming Tuesday afternoon through Wednesday.

- Snow will continue in the higher elevations of the mountains, with snow levels falling to the lowest elevations (between 7000 and 7500 feet) from later Tuesday through Wednesday morning.

- Accumulating snowfall is expected across the higher elevations of 9,000+ ft through Wednesday morning.

- The first freeze of the season for many low elevation locations east of the Divide may be around the corner. Friday morning lows are currently forecast to be near or below freezing.

UPDATE

Issued at 131 PM MDT Mon Oct 12 2026

A few updates to the near term forecast but overall much of the previous forecast discussion remains on track. First, low level stratus and some patchy areas of fog linger across much of central and northern WY. This will likely hinder warming, resulting in temperatures being cooler than originally forecast. Currently, highs are forecast to get into the low to mid 40s across much of central and northern WY. Warmer temperatures are forecast for southern WY where cloud cover is more scattered in nature. Showers and a few thunderstorms will be possible throughout much of the day and into Tuesday. The greatest chances for precipitation will remain over central and southern WY with rounds of showers over the next 24-48 hours. The heaviest periods of precipitation look to occur Monday evening and Tuesday afternoon/evening. Winter precipitation is the other aspect of the near term forecast. This next round of precipitation will bring some more accumulating snow to the higher elevation mountains. The Wind River Range in particular looks to get a good bit of snow. Probabilistic guidance is showing a 50-80% chance for elevations of 9,000 ft or higher seeing 6 or more inches of snow. There is around a 20-50% chance for the highest elevations of the Wind River Range to see amounts nearing 12 inches. Due to this, the first Winter Weather Advisories of the 2026-2027 season will be issued for both sides of the Wind River Range. Advisories will go into effect at 21Z Monday and last through 12Z Wednesday. There may be some lulls in precipitation between sunrise Tuesday to noon. Other high elevation mountains will see some accumulating snow as well. The Absarokas, Gros Ventre, Tetons, Wyoming/Salt River Ranges, and the Bighorns will all see some snow during this period as well. However, due to a less favorable track of this system amounts look less and more isolated for these other high elevation locations. Lastly, the first freeze of the season may be around the corner for many low elevations that have yet to see temperatures hit 32F. Wednesday and Thursday mornings look to have some isolated chances for near freezing morning lows mainly across southern WY. However, confidence is growing on a widespread hard freeze (<28F) possible Friday morning. At this moment no freeze related products will be issued but they may be needed over the next 24-48 hours.

DISCUSSION

Issued at 232 AM MDT Mon Oct 12 2026

Fall has finally arrived to the area. Sunday was the coolest day may locations have seen since May. And it looks like we are through with the record high temperatures for a while, although we should see some moderation in temperatures toward seasonal normals toward the end of the week.

The moisture from Rachel that moved over the area today is now moving away to the north and east. We still have some showers across the area, although most of the precipitation is on the light side. Notice how I said precipitation though. There has been some snow in the mountains. And even in the lower elevations, we have seen some mixing in places like Cody and Powell, although there have been no reported problems with roads. The general trend should be down through the night, although some rain and mountain snow will linger until morning.

Our attention now turns away from the moisture from Rachel to that big bowling ball to west, AKA an upper level now swirling over Oregon. This feature has been giving me fits over the details of its direction, and, most importantly, the ultimate impacts of the weather across western and central Wyoming. And the good news is we finally have somewhat better agreement in the path of it. The models are digging the low a bit further south, both the operational GFS and European models, as well as a majority of the ensemble members dig the low further south, moving across the Great Basin to near Las Vegas by Tuesday evening. The result at this point looks to be somewhat less precipitation. There should be somewhat of a lull this morning as we will be in between systems. There are some indications of a weak meso low that may try to move into the area, but the models are split on this. Nevertheless, the majority of the showers will fall West of the Divide today, especially during the day. Northeastern portions of the County Warning Area may have a mainly dry day today. Another wave should bring an increase in showers tonight. However, there is a decent spread of where the most numerous showers will fall. And it will be a cool day as well, with below normal temperatures. As for precipitation amounts, I will talk about those in separate paragraphs further down. As for the high wind warning, we will let it ride until expiration. We will let the freeze warning ride for now. And, with the cold comes snow. We will also discuss that in another paragraph.

Tuesday looks like a similar day with cool temperatures and most of the showers across southern and western Wyoming with fewer further to the north. The low will begin to make a turn toward the northeast Tuesday night and into Wednesday. This is when the wettest period should be for areas East of the Divide as flow turns more easterly, bring an upslope component. It should be noted though that with the low further to the south, we will closer to the edge of the moisture so precipitation amounts have been cut, to about half of what they were yesterday at this time. Showers should linger into Wednesday before gradually ending as we head into Thursday as the low moves away. Which way it moves depends on what model you believe, but most agree it will move away. Dry weather should then return Friday and into the weekend as flow turns zonal as flat ridging builds, bring a return to near normal temperatures.

PRECIPITATION AMOUNTS...I will break this up into two different segments. The first will be the twenty four hours through tonight. No surprise, the highest amounts will be across western and southern Wyoming, with the 1 out of 2 chance line roughly running south of a Jackson to Casper line. The chance of a half an inch or more is generally 1 out 2 across the southwestern quarter of the state. The epicenter is, no surprise across the western slopes of the Wind River Range were where is a 1 out of 2 chance of an inch or more. Amounts decrease further north where many areas may end up with a mainly dry day. As for Tuesday through Wednesday night, all areas have at least a 1 in 2 chance of a quarter of an inch or precipitation, south of a Jackson to Buffalo line as the main concern for precipitation shifts to central and southern Wyoming. When we bump it up to an inch, the main concern switches to the east to northeasterly upslope locations East of the Divide, mainly along and south of US 20 26 from Dubois to Casper, with lesser amounts across western Wyoming as the upper level low moves further to the east. Some locations, especially the Wind River Range have the potential to pick up an additional two inches of QPF by Thursday morning.

SNOWFALL...Snow level at this time are generally running between 8000 and 8500 feet this morning in central Wyoming to around 7000 feet in northern Wyoming in regards to accumulating snow. Through the day today, snow levels should remain in in this vicinity so above most passes. The exception would be Togwotee although warm ground temperatures are keeping any impacts from the roads. The best time for snow levels to lower would be later Tuesday through Wednesday as flow turns more northeast. The 700 millibar temperatures way fall as low as minus 2 to minus 3, which could bring snow levels down as low as 6500 to 7000 feet, especially in vicinity of the Wind River Range, Tetons, Absarokas and Salt and Wyoming Range. This period from Tuesday through Wednesday looks to be the most impactful of the period, so this is when the first winter weather advisories my be needed. For three inches of snow, most of the mountains ranges have at least a 1 in 2 chance at the higher peaks. Advisories in the mountains are for 6 inches or greater though. And although a few locations have this, the most widespread location would be the Wind River Range, where most locations above 9000 feet have at least a 3 out of 4 chance. A decent portion of the Wind River Range has a 1 out of 2 chance of at least 12 inches of snow, but this would be in places well away from the main travel routes. So, the likely highlights needed would be advisories and not warnings. Some of the highest locations, like Gannett Peak, may end up with over 30 inches of snow by the time the upper level low moves away on by Thursday.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 345 PM MDT Mon Oct 12 2026

MVFR conditions at most locations to start the period and through the overnight hours with on and off precipitation in the form of rain. Some improvement early morning ahead of the next round by mid morning around 13-16Z, with RKS likely to remain dry and improve to VFR as winds increase to 25kt gusts after 18Z with daytime heating and mixing. Otherwise, all other locations remain relatively dry 10kts or less through the entirety of the period. Mountain obscuration will continue to factor in the entirety of this period and into at least the next TAF cycle or two into Wednesday morning with lingering precipitation and after storm fog/stratus.

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

Winter Weather Advisory until 6 AM MDT Wednesday for WYZ014- 015.