textproduct: Western and Central Wyoming

KEY MESSAGES

- Cloud cover increases across the far west and southwest Monday night with a few light showers possible by sunrise Tuesday.

- A weak system pushes across the region Tuesday with isolated shower activity (~20%) across higher terrain, mainly west of the Continental Divide. No significant impacts expected.

- A weather system generates gusty southwest wind Thursday and especially Friday, with rain and high elevation snow late Thursday through Friday. Confidence in precipitation totals and snow levels is low at this time.

- Much above normal high temperatures prevail through Thursday before beginning to cool Friday. Weekend daytime highs will be around or slightly below seasonal averages.

UPDATE

Issued at 1232 PM MDT Mon Oct 19 2026

The next few days remain seasonable and mostly dry. Latest hi-res models continue to put weak, isolated (15-30% chances) rain showers over the western mountains from about sunrise Tuesday through late evening. Otherwise, focus remains on the bigger system for late this week. Details still have low confidence, but high elevation snow (9000+ feet) is still looking likely, with the main impacts being to western mountain passes Friday morning; impacts look minor at this time however. Details should become clearer over the next couple days.

DISCUSSION

Issued at 130 AM MDT Mon Oct 19 2026

IR currently depicts mainly clear skies into Monday morning with some passing clouds through Sweetwater County pushing east by sunrise. Water vapor shows weak upper level southwest flow across the CWA with the main finger of the PFJ well to the north supporting a low off the Pacific northwest coast. This will deepen with its southward progression Monday into Tuesday with increasing divergence aloft. Seasonable temperatures and relatively light or modest winds 10 to 20 mph through mid week expected. A weak shortwave will propagate across the southwest flow Tuesday afternoon and evening that will bring isolated shower activity for higher terrain, mainly west of the Divide. Low coverage is expected ~20 percent with no significant impacts expected.

As the aforementioned low starts to move east across southern California Wednesday, models indicate it becoming more of an open and more progressive wave. This will then push along the southwest flow across the upper Rockies not of high of an impact with its quicker movement. However, models are not in the best of agreement and QPF amounts fluctuate with each model run. With this run, it has bumped up for mountain snow, especially for western mountains but does include the Bighorns. With the seasonable to just above temperatures, expect valley/basin rain, even west of the Divide below 8-9kft. This will be the biggest weather event to keep an eye on for headlines going forward for late Thursday into Friday, stretching into the weekend, all dependent on how quickly it progresses with its east to northeastward movement. Beyond that, induced ridging will be short lived ahead of another low off the Pacific northwest extending in from the GOA that could be more impactful with a more reinforced colder air and lower freezing levels. Stay tuned for updated forecasts in the coming days, but enjoy the quieter weather leading up to later in the work week.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 950 PM MDT Mon Oct 19 2026

All terminals to be VFR through 06Z/Wednesday. The upper flow backs to the south-southwest Tuesday in response to a digging trough along the US West Coast. Mid-level moisture spreads north across far west Wyoming overnight and Tuesday morning, leading to isolated light showers within a BKN mid-level cloud deck. KJAC has a less than 30 percent chance of seeing a few sprinkles, mainly between 09Z-15Z/Tuesday. With the mid-level moisture in place, daytime heating helps to initiate convection over the western Wyoming mountains by early Tuesday afternoon. The chance of precipitation remains less than 30 percent with minimal impacts if a shower did move across a terminal. Terminals west of the Continental Divide, and perhaps KCOD, have the best chance at seeing a late Tuesday shower before sunset arrives. Other than a 4- to 6-hour period of 10-18kt winds at KCPR during the morning and early afternoon, wind speeds at all terminals should be less than 10kts through the period.

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

RIW WATCHES/WARNINGS/ADVISORIES

None.