textproduct: Western and Central Wyoming

KEY MESSAGES

- The next weather system pushes in Sunday morning spreading northeast throughout the day.

- Mainly rain in eastern basins changing over to snow after sunset. Highest impacts across the Bighorns to northern Johnson County.

- Continued active pattern with little impacts expected Monday through Wednesday.

- Dry conditions and a warming trend for the end of the week and into next weekend.

DISCUSSION

Issued at 130 AM MDT Sun Apr 26 2026

IR currently depicts increasing cloud coverage pushing in from the southwest with the next system over Nevada to northern Utah as it progresses to WY by early Sunday morning. WV shows the main finger of the PFJ pushing around an upper level low along the MT/Canada/ND tri-point with a jet max of around 120kts around the base of the L/W trough positively oriented extending southwestward to northern California. This next weather system with progress northeastward through the day Sunday as the PFJ moves northward as well with ample support and deepening due the increased divergence aloft out of the base of the aforementioned trough. Southwest flow will be conducive to increased precipitation for points east of the Divide and the southern areas of the state. Highest impacts to the western Winds (although to higher elevations and nothing of note to South Pass, but mostly to the passes of the Bighorns to northern Johnson County. Precipitation type for much of Sunday for eastern Basins will remain rain until sunset before it switches over to snow. There is even a bit of instability of around 100-200 J/kg across eastern Sweetwater to Fremont/Natrona Counties for a few possible rumbles of thunder Sunday afternoon. Storm chances will end before sunrise loses what warmth there will be for instability as precipitation changes over and starts to fill in across the Wind River Basin to eastern counties towards midnight and through the overnight hours.

Snow accumulations for the Bighorn mountain passes are likely to range from 6 to 10 inches (80-90% confidence) trickling down across northern Johnson County into early Monday morning. Highest wind speeds will be across this area pushing 30 to 35 mph. Coupled with an inch or two of snow (60-70%), expect some travel impacts before sunrise and lingering into the Monday morning commute. As such, a winter weather advisory has been issued to account for this, with any lingering snow and impacts to push east by mid morning Monday. The remainder of Monday will be much less active with some convection possible for Sweetwater County south of the I-80 corridor with the next shortwave skirting further south as the main upper level low starts to push east.

Overnight Monday into Tuesday, the low continues to the east and lift more north as the PFJ brings in a more northwest flow aloft. Precipitation will be more limited to the northern half of the CWA bringing some minor impacts to the northern mountains and Yellowstone as the jet weakens in support of the upper level low with decreased divergence in its wake. Wednesday will continue this trend as the low is even further east and impacts expected to be across the Bighorns to eastern counties as the cooler trend will come to an end. There after, expect some weak upper level ridging to build in from the southwest that will give way to drier conditions and a slight warming trend going into next weekend. The next thing to keep an eye on will be early the following week with a low/trough to the southwest dependent on if it remains closed or becomes an open wave. Stay tuned, but the short term looks to remain active brining some much needed moisture to much of the area.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1057 PM MDT Sat Apr 25 2026

An incoming system will bring widespread precipitation impacts to terminals this period. Rain and snow will begin increasing across southwestern Wyoming between 10Z and 12Z, bringing MVFR impacts to KRKS and then IFR impacts to KBPI and KPNA. Mostly rain is expected through the day Sunday, with precipitation spreading east of the Divide by late morning. MVFR to IFR impacts are then expected at most terminals through Sunday evening, with rain transitioning back to snow after 00Z Monday and focusing most on areas east of the Divide. The most persistent IFR impacts are expected at KCPR, KLND, and KRIW. Conditions will generally improve for KBPI, KJAC, and KPNA after 00Z Monday. Frequent mountain obscurations are expected through the period after 12Z today.

RIW WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory from 3 PM this afternoon to 9 AM MDT Monday for WYZ008-009.

Winter Weather Advisory from 6 PM this evening to 9 AM MDT Monday for WYZ010.