textproduct: Western and Central Wyoming

KEY MESSAGES

- Isolated areas of fog/low clouds in the Upper Green River Basin this morning and possibly the Jackson/Star Valleys.

- Monday will be dry and high temperatures several degrees warmer. Breezy afternoon westerly wind 20 to 30 mph occurs over southwest Wyoming into Natrona County as well as near Dubois and Cody.

- The next storm system arrives in western Wyoming Monday night into Tuesday. Light snow gradually spreads east of the Continental Divide Tuesday evening and persists through the Wednesday morning commute.

- Northwest flow aloft favors additional light snow in the western and northern mountains late in the week. Temperatures across the region remain seasonal heading into next weekend.

DISCUSSION

Issued at 122 AM MST Mon Dec 1 2025

Snow ended across the area earlier Sunday evening. Apart from a few high clouds, skies will be clear this morning for most of the area. Some low clouds/fog could push into the Star Valley in the next few hours, as well as areas along Hwy 28 near Farson. Conditions will remain dry today, with temperatures about 5 to 10 degrees warmer. Some locations will be 15 to 20 degrees warmer from Sunday, due to highs in the teens yesterday. Winds will be a bit breezy today, with gusts of 25 to 30 mph occurring across southern portions and Natrona County. Areas near Dubois and Cody will also be breezy, with locally higher gusts around 35 mph.

Another storm system will quickly make its to the CWA from the north this evening, with snow developing over northwestern portions by 04Z Tuesday and spreading southward through the rest of the night tonight. Winds will increase over the east slopes of the Absaroka and Wind River Mountains irt this latest (third) storm system. West to northwest winds, with gusts of 35 to 45 mph, will develop by 06Z and continue through much of the day Tuesday. These conditions will occur at Dubois, Cody and Clark as well. These winds will then spread across southern portions of Fremont and Natrona counties by 12Z. Gusts of 50 to 55 mph will be possible along Hwy 258 on the south side of Casper. Gusts of 25 to 30 mph will then be common after 18Z across areas west of the Divide and portions of the Wind River Basin. Isolated snow showers will also occur across areas east of the Divide through the afternoon and become more widespread in the evening, as the associated cold front makes its way southward. This system will be a bit slower than the previous two, with light snow continuing through Wednesday morning. Snowfall amounts of 1 to 2 inches is expected over central portions and the western valleys, with 3 to 6 inches in the mountains.

Snow will end across the area through the rest of the morning Wednesday, as high pressure builds into the area from the north through the afternoon. Conditions will remain dry Wednesday night and Thursday, with a chance for snow over northwestern portions due to upslope flow from another incoming system on Friday. Impacts from this storm will be widespread once again, however it will track further north so snowfall amounts look to stay on the light side again. Periods of snow look possible Friday and Saturday across western portions, due to the semi-consistent upslope flow. Exact details will become clearer in the next few days as we progress through the week.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 403 AM MST Mon Dec 1 2025

At KPNA, IFR flight conditions should begin to improve between 14Z- 16Z this morning. Then, VFR flight conditions are forecast most of the TAF period all West of the Divide terminals. Moisture begins to filter into the region after 00Z Tuesday, resulting in increasing cloud cover and occasional mountain obscuration. There is a 20% chance of MVFR ceilings at KJAC and KPNA after 08Z Tuesday and these chances are reflected in a prevailing SCT030 group. The disturbance aloft associated with the increased moisture will reach western Wyoming/KJAC late in the period, bringing a 30% chance of snow showers at KJAC between 06Z-12Z Tuesday. Chances at KPNA, KBPI, and KRKS are between 10%-20%, so there is no mention in TAF at this time. MVFR flight conditions could accompany any snow showers.

At KRKS, KPNA, and KBPI, winds increase between 17Z and 20Z with gusts between 20-30kts and continue through the evening. Expect KRKS to be the gustiest terminal. At KJAC, expect winds to become gusty as the disturbance aloft approaches after 06Z Tuesday.

East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals.

VFR flight conditions are forecast this TAF period. Moisture begins to filter into the region after 00Z Tuesday, resulting in increasing mid level cloud cover and occasional mountain top obscuration. After 16Z, winds increase with gusts around 25kts at KCPR until 00Z Tuesday when gusts subside. KCOD is forecast to become gusty after 02Z Tuesday as a disturbance aloft begins to shift into the region. There is a 20% chance in gusty west-northwest winds between 20-30kts at KRIW after 07Z Tuesday, however, given these low chances there is no mention in TAF at this time.

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

RIW WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory from 11 PM this evening to 11 PM MST Tuesday for WYZ012.