textproduct: Western and Central Wyoming

KEY MESSAGES

- Light snow continues across portions of western WY this morning, with periods of moderate to heavy snow over the Tetons and Salt River Range.

- There is a slight chance for rain or a rain/snow mix over southern portions and areas east of the Divide through the rest of the morning. Any slick spots will be very isolated.

- Locations east of the Divide remain above normal temperature- wise and mostly dry through much of the weekend.

- Another disturbance looks to bring more snow to western WY starting Sunday into Monday.

DISCUSSION

Issued at 112 AM MST Fri Jan 2 2026

Light snow will continue in the Jackson and Star Valleys this morning, as the inversions that had been in place Tuesday and Wednesday held firm Thursday. This kept temperatures firmly below freezing through the day, in the middle 20s. Accumulations will remain light this morning, with low clouds/fog in place as well, with an additional 1 to 2 inches expected and the clouds/fog lifting/scattering out by midday. Moderate to heavy snow will also continue over the Tetons and Salt River Range this morning, with an additional 12 inches expected. Elsewhere in the western mountains, up to 4 inches will fall today. Isolated rain showers will continue across areas east of the Divide and southern portions this morning, gradually ending toward 18Z as a subtle shortwave traverses over the CWA and pushing the available moisture to the southeast. Temperatures are expected to stay above freezing in these areas and any possible patches of ice will be isolated. There is low confidence in temperatures rising above freezing in the western valleys today, as a transitory begins to build over the region this afternoon. This will allow for the inversion to reform and keep the cold air trapped in the valleys.

As was just mentioned, a transitory ridge will build back over the region during the day today, as a strong closed upper low moves over the EPAC toward the West Coast. Dry conditions and above normal temperatures will be in place across much of the CWA once again this weekend as a result (especially east of the Divide). A leeside trough will develop over eastern WY by 12Z Sunday, due to southwest winds aloft as the ridge transitions eastward. The timing for the strong to high winds looks to be shifted forward in time toward Sunday morning, as 700mb winds increase to 50 to 60kt over South Pass and southern portions of Natrona County. Any high winds (wind gusts 60+ mph) look to be brief during the day however, as winds look to be more west-southwest, as opposed to a more favorable southwesterly direction. The timing for the next round of snow has also shifted toward Sunday morning, as the first shortwave from the upper low looks to reach western portions by 12Z. Southwest flow aloft will continue Sunday into Monday, leading to a persistent flow of moisture. However, this direction is not as conducive for higher snowfall amounts. 700mb temperatures are forecasted to be around minus 4 to minus 6C (which corresponds to snow levels of 5500 to 6500ft), which will keep the precipitation as snow in the western valleys. Will have to see if this trend holds, as snow levels would be expected to rise in this flow pattern. Initial snowfall amounts Sunday through Monday look to be in the 6 to 12 inch range across the western mountains.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 945 AM MST Fri Jan 2 2026

MVFR conditions at JAC/BPI with fog and stratus with recent snowfall. PNA/RKS has already lifted to VFR but all locations will remain low but VFR due to ceilings after the 20Z mark. Otherwise, gusty winds up to 35kts at RKS and 25kts at CPR. Mid level ceilings remain east of the Divide throughout the period lifting to the upper levels by 12Z Saturday morning. Fog development likely (40-50%) to occur once again west of the Divide after 01-03Z due to radiational cooling overnight. Worst conditions at BPI once again with model guidance pointing towards that Saturday morning. Otherwise, improvements after 14-16Z towards the end of the period when all locations will scatter out for Saturday afternoon and into Sunday ahead of the next system into early next week.

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 5 PM MST this afternoon for WYZ012-024.