textproduct: Western and Central Wyoming

KEY MESSAGES

- Showers continue to end across the area, but are expected to continue over the Wind River Basin. Accumulating snow is expected for locations like Riverton and Lander through the overnight hours, before ending after sunrise Thursday morning. - Isolated showers will return across the area Thursday afternoon, with little to no impacts.

- Drier and milder conditions return to the Cowboy State for the end of the week into the weekend.

UPDATE

Issued at 1233 PM MDT Wed Apr 29 2026

Scattered showers have already begun to develop across the Cowboy State. Precipitation will continue to spread this afternoon with most seeing a 10-40% chance for a brief shower. The main focus turns to late tonight into the morning hours on Thursday. Hi-res models remain locked in on a meso-low developing in association with a passing shortwave. This low will create a period of northerly/northeasterly flow for locations east of the Divide. This flow will create winter impacts for places along the eastern slopes of the Wind River Range and the higher elevations of the Owl Creek, southern Absaroka and northern Bighorn Ranges. As for lower elevations, portions of the Wind River Basin and the Lander Foothills look to have the best chances to see some impacts.

Currently, the bullseye is across the Lander Foothills, where favorable northerly/northeasterly flow up to 700mb will create a period of moderate to heavy upsloping Wednesday night into Thursday morning. PWATs are on the higher end with values around 0.40-0.50 inches, which sits about 110-120% above normal for this time of the year. Mixing ratios are looking favorable as well, with values sitting steady at 3 g/kg across much of the region. Temperatures are the main limiting factor and it is causing some models to struggle when it comes to forecasting possible snow accumulations. 700mb temperatures initially look to be on the fringe of favorable values. So its likely that precipitation during the evening hours Wednesday will fall as rain or a rain/snow mix. As precipitation intensifies after midnight, these values will likely cool further into the minus 6C to minus 8C range. This cooling eventually works its way down to the surface allowing for precipitation to fully transition over to snow and snow accumulation to begin on grassy surfaces. From midnight through sunrise, precipitation will persist across the eastern slopes of the Wind River Range. Depending on how intense the flow is, there may be some precipitation stretching far enough off the mountains to reach Riverton. Lander looks to be socked in with a period of moderate to heavy snowfall. While the sun is still down, snow will be able to accumulate along the grassy surfaces and possibly some paved surfaces. Models struggle with estimating snowfall amounts during these late season events, so some manual adjusting was needed. By sunrise Thursday, amounts of 1-3 inches are expected in downtown Lander mainly on grassy surfaces. The higher elevations up into the Lander Foothills may see some localized amounts nearing 4 or 5 inches. As for the remainder of the basin including Riverton, amounts become a bit tricky due to the dependence on precipitation stretching off of the mountains. Due to this, amounts are forecast to range from a coating to possibly an inch with higher amounts possible for locations such as Hudson or other places closer to the Wind River Range. Precipitation may linger after sunrise with showers gradually dissipating through the mid to late morning. After sunrise, little to no additional snow accumulation is expected to occur. The remainder of the forecast period remains mostly unchanged with the previous discussion still valid.

DISCUSSION

Issued at 200 AM MDT Wed Apr 29 2026

IR currently depicts ample clouds pushing in from the northwest down the upper level ridge to the west and weak troughing over the northern Rockies. WV shows the PFJ dipping around these features with a modest 90-100kt jet at the base of this positively tilted shortwave with its slow eastward progression. Weak diffluence aloft is giving way to a few scattered showers ongoing over the eastern Bighorn Basin and Bighorns themselves, but weakening as the early Wednesday morning progresses. Through the day Wednesday, some isolated shower activity for the northern half of the CWA but not expected much with low confidence on any impacts to be had during daylight hours. Similar temperatures and winds as it was Tuesday.

Models are more aligned with each other of the shortwave to deepen after sunset and into Thursday morning elongating further southwest than what previous models have shown. As such, shower activity Wednesday night looks to be more active across the southern Bighorn Basin and much of the Wind River Basin. CAMs show a weak meso low to develop at the base of the trough that will be enhance for upslope along the northern Owl Creeks and Lander Foothills/eastern slopes of the Winds. With the colder temperatures overnight, any liquid precipitation will turn to snow after midnight through the early to mid Thursday morning hours. 1 to 2 inches likely for the Lander Foothills (60-70%) with a few outliers of 3 to 4 inches possible (20-30%) dependent on how fast the aforementioned shortwave lifts out to the northeast. When this occurs, precipitation will diminish by mid Thursday morning. A light accumulation of an inch of so for the upslope of the Owl Creeks, and at least a dusting to a couple tenths possible (40-50%) for the other parts of the Wind River Basin to include Riverton itself. Otherwise, expect improving conditions quickly through the remainder of Thursday morning and especially into the afternoon and evening hours. Temperatures about the same Thursday as well, but upper level ridging expected to build in overnight into Friday and the weekend.

As the ridge builds, ample convergence aloft will help aid in dry conditions and a warming trend through early next week as well. Temperatures during the afternoon back into the 70s east of the Divide and 60s to the west starting over the weekend, perfect for a trip to the parks and wildlife viewing. The next system to keep an eye on will be by Tuesday/Wednesday next week as the EC keeps trending towards a closed upper level low coming up from the Desert Southwest combining with the PFJ dipping further south across the upper Rockies once again. How this comes together is up in the air, but this will tend to evolve into a quicker moving open wave that will have minor impacts at best going forward further into the long term forecast. Stay tuned for updates in the coming days as the weather quiets down for the end of the work week and especially over the weekend.

RIW WATCHES/WARNINGS/ADVISORIES

None.