textproduct: Western and Central Wyoming

KEY MESSAGES

- Mountain snow continues across western WY with western valleys seeing periodic shower either in the form of snow or a mix or rain/snow.

- Strong gusty winds return to the state similar to earlier this week with the potential for widespread gusts of 60 mph or more across portions of southern, central, and northern WY.

- A cold front arrives late tonight into early Saturday morning. The front will decrease winds and ahead of it bring chances for showers east of the Divide.

DISCUSSION

Issued at 242 AM MST Fri Dec 19 2025

The upper level low that is contributing to the weather across the Cowboy State today is currently north of the region sitting along the border of Canada and the US. This low will continue to make its way east through the day today, a jet streak associated with this system will move over the state today. Hi-res models show 700 mb winds of 60 to 75 knots across portions of southern, central, and northern WY. Similar to earlier this week these 700 mb winds will translate to widespread strong gusty winds at the surface. The upper level low to the north will lead to flow from the southwest which creates the potential for mountain waves over parts of the state. The main areas of concern will once again be along the eastern slopes of the Wind River, Absaroka, and Bighorn Ranges. This includes locations around Lander, Cody, and Buffalo where again wind gusts of 70 mph or more may be possible at times today. Other locations will see these strong upper level winds mix down to the surface at times today. The Wind Corridor from Casper to Rock Springs and portions of the Green River Basin look to see wind gusts of 55 to 70 mph. Probabilistic guidance shows a 50-80% chance for gusts exceeding 60 mph for the locations previously listed. As a result, High Wind Warnings have been issued and remain in effect for portions of southern, central, and northern WY. Gusty winds will persist through much of the day until an associated cold front from the system to the north moves across the state. The frontal passage will cut off the strong winds leaving breezy conditions through the overnight into Saturday morning.

Snow continues to fall across portions of western WY this morning. Precipitation will persist over the area through most of the day today with periods of moderate to heavy snowfall expected across the higher elevation mountains. Temperatures are forecast to range in the upper 40s to around 50 east of the Divide and mid to upper 30s west of the Divide. Temperatures will play a role in just how much additional snow accumulates across western valleys through the day today. Warming temperatures may lead to transition from snow to a mix of rain/snow or even possibly rain at times, which would hinder accumulations. Winds will begin to increase through the morning with southwesterly winds of 15 to 25 mph along with occasional gusts of 30 to 35 mph. This may lead to some areas of blowing snow and hazardous driving conditions across western WY especially along mountain passes such as Togwotee and Teton Passes. Precipitation is expected to gradually dissipate through the evening into the early morning Saturday ahead of the approaching cold front. Additional snow accumulations range from 10 to 20 inches over the higher elevations of the Teton, Gros Ventre, Salt River/Wyoming, Wind River, and Absaroka Ranges along with southern YNP. The highest peaks of these ranges may see additional accumulations of 20 to 30 inches. As mentioned earlier the warm temperatures will likely limit snow accumulations across western valleys. Additional accumulations for these locations look to range from 2 to 6 inches with lesser amounts in parts of Star Valley and around Pinedale. As a result western valleys and the upper Green River Basin remain in Winter Weather Advisories. The previously mentioned mountain ranges have Winter Storm Warnings in effect through early Saturday morning.

The timing for the cold front looks to be late this evening into Saturday morning. While the front will begin to cut off winds it will also bring chances for precipitation east of the Divide ahead of it. Temperatures will initially be too warm for snow as scattered showers move across central and northern WY later this evening. However, cold air should quickly follow behind leading to the possibility for some snow to fall east of the Divide. Depending on how quickly this cold air can move in there is some potential for light snow accumulations. The best chances look to be over portions of Johnson and Natrona Counties where a quick coating to inch or two may fall before sunrise on Saturday. Otherwise most locations can expect a trace to little or nothing in terms of snow accumulations. One thing to keep in mind is that any liquid precipitation that does fall will likely quickly freeze as the front moves through, so some slick spots may be possible Saturday morning.

The remainder of the forecast period sees the active pattern continue. A brief lull looks to occur Saturday and parts of Sunday before another potential system impacts the region. At this time the greatest likelihood for impacts would be western WY but that may be subject to change. As for temperatures, warm well above normal values return for the upcoming holiday week. Long range models are showing a return of mid to upper 50 degree highs east of the Divide and low to mid 40s west of the Divide. As a result the potential for a white Christmas is looking very slim for anywhere outside of western WY.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 1110 PM MST Thu Dec 18 2025

West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals.

IFR conditions at KBPI, KJAC, and KPNA are expected to improve over the next couple of hours as a relative lull sets in ahead of the next push of snow. This will arrive around 12Z, returning IFR conditions to KJAC by sunrise Friday. Impacts will arrive later at KBPI and KPNA. Wind will also be accompanying this system, and west to southwest gusts of 25 to 35 knots will be seen for much of the period. KRKS is less favored to see precipitation impacts but will see wind gusts to 40 knots after 18Z Friday. KJAC should most persistently see IFR conditions, with an improvement to MVFR expected late in the period. Mountain obscurations are expected through the period.

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

Wind will continue to be the main concern east of the Divide. Gusts of 30 to 50 mph will be widespread through much of the period, strongest at KCOD, KCPR, and KLND. Precipitation will have a harder time making it east, with the best chances coming late in the period which may bring MVFR conditions to several terminals.

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 Storm Warning until 5 AM MST Saturday for WYZ001-002- 012-014-015-024.

High Wind Warning until 5 PM MST this afternoon for WYZ003- 005>007-009>011-016.

Winter Weather Advisory until 5 AM MST Saturday for WYZ013-023- 025.

High Wind Warning from 8 AM this morning to 5 PM MST this afternoon for WYZ018-026-028>030.

High Wind Warning until 11 PM MST this evening for WYZ019-020- 022.