textproduct: Western and Central Wyoming

KEY MESSAGES

- A quick-moving weather system brings light snow across southern Wyoming through this evening. Minor winter travel conditions for portions of I-80 through about 5pm MST.

- Monday is dry, with high temperatures a few degrees warmer. Breezy afternoon winds 20 to 30 mph occur over western Wyoming and into Natrona County.

- Multiple weak weather systems are expected this week, bringing light snow chances and keeping temperatures cool to seasonal. The best chance for widespread light snow comes Tuesday and Tuesday night.

UPDATE

Issued at 1119 AM MST Sun Nov 30 2025

No major changes with today's forecast. A quick-moving weather system brings light snow to southern Wyoming through this evening. It seems to be slightly further south than previous models had, resulting in snow amounts coming down ever so slightly, with chances decreasing across Jackson Valley and the northern Green River Basin. The main impacts remain to be for any travel along I-80 and southern Lincoln County, were some snow and breezy winds (20 to 25 mph) could cause minor winter travel conditions through about sunset.

DISCUSSION

Issued at 201 AM MST Sun Nov 30 2025

It is a quiet, but rather cold night here at the humble Riverton weather abode. Some locations are having their coldest temperatures so far this season. Things will turn a bit more active again today though.

The culprit for this is a weak area of low pressure that will drop across Idaho and then into Utah and Colorado today. This does not look like a big storm for us given that the system is fairly moisture starved and the best dynamics will remain to the south of Wyoming. As a result, snowfall amounts look relatively small. Ensemble guidance gives at most a 1 in 3 chance of 2 inches or more in the southern Star Valley and southern Lincoln County, with most other lower elevation locations having at most a 1 in 2 chance of an inch of snow. Nevertheless, there could be some impacts on a busy travel day at the end of the Thanksgiving holiday weekend, including Interstate 80. Not enough for an advisory though. The highest amounts will occur in the Salt and Wyoming Ranges, but even here there is only at most a 1 in 3 chance of 4 inches across the higher peaks with a near zero chance of 6 inches. As for elsewhere, a few snow showers could jump the Divide but any amounts east of the Divide would likely be slim to none. The time of most impacts would be from around 9 am to 4 pm, with all snow ending by midnight tonight as the system moves away to the south and east. Otherwise, expect another cold day with temperatures averaging 5 to 10 degrees below normal under mostly cloudy/overcast skies.

High pressure should bring a dry start to the work week on Monday with temperatures climbing closer to seasonal normals, as our air mass modifies a bit. There will be a gusty wind in the Wind Corridor from Rock Springs through Casper ahead of the next weather system. This system will bring impacts for Tuesday into Tuesday night. Most areas have the potential for more accumulating snow. Ensemble guidance gives much of northern and central Wyoming at least a 1 out of 3 chance of 2 inches of snow or more, although again this does not look like a major storm, with the chance of 6 inches or more generally less than 1 out of 4 except in the mountains. The problem with this system is that there are a lot of moving parts and guidance still has a rather substantial spread on most aspects including timing and placement of the heavier snow. So, confidence is fairly high there will be some snow, but exact details are still uncertain. Then, after a dry Thursday, another system may approach for the end of the week and next weekend. Like Tuesday's system, there is still a decent spread in guidance and details are difficult to resolve this far out. Temperatures should average fairly close to seasonal normals, with the coldest temperatures expected Wednesday behind the next cold front. However, no arctic outbreaks are expected for the next week.

East of the Continental Divide (KCOD/KCPR/KLND/KRIW/KWRL)

With the latest weather system staying to the south today, snow impacts will be minimal. KCPR may see light snow during the next couple hours before ending. Remaining sites hold mid level cloud cover through the rest of the afternoon before clearing overnight. Conditions are favorable for some fog on Boysen Reservoir tonight, which may briefly drift toward KRIW around 12Z. Chances remain low, so nothing in TAF for now.

Please see the Aviation Weather Center and/or CWSU ZLC and ZDV for the latest information on icing, turbulence, and smoke forecasts.

RIW WATCHES/WARNINGS/ADVISORIES

None.