textproduct: Western and Central Wyoming

KEY MESSAGES

- Low pressure passing by will bring a low chance for showers again today, mainly for the western mountains, the Bighorns, and Casper Mountain. Accumulations will be minimal.

- A more potent late winter system sweeps into Western Wyoming starting Wednesday and continuing through Friday. Ample cold temperatures will bring snowfall to most of the region, including lower elevations.

- A hard freeze is expected east of the Divide Thursday night and Friday night. The likelihood of temperatures falling below 28 degrees is high (>90%), with temperatures possibly falling into the teens.

DISCUSSION

Issued at 145 AM MDT Tue Apr 14 2026

Finally a more active pattern across Wyoming trying to bring precipitation! The latest system is a trough ejecting into the central Plains from the Sour Corners region. This system is set a little too far south to bring a significant amount of precip, but still enough energy to produce precip for areas of Casper Mountain, the Bighorns, and higher elevations of the Tetons.

But this does set the table for a potent late winter storm diving out of the PacNW into the northern Rockies. This system starts to spread precip into the NW mountains during the day Wednesday before slowly moving east Thursday and Friday. The system will be accompanied by ample moisture, so the potential for meaningful accumulations is improving. The system will also be accompanied by a strong push of colder air, so most precip will be snowfall, especially Thursday night into Friday. This includes most of the lower elevations as well, with the current forecast totals of 2 to 5 inches. Winter Storm Watches have been posted for the northwestern Mountains and YNP for this system, and may need to be expanded is the snow forecast increases with later updates.

The other concern with this next system is the significant cold air push coming with and behind the next system. Cold temperatures will arrive during the day Thursday, with lows Thursday night in the low to mid 20s east of the Divide and in the teens west of the Divide. The main core of the cold air then settles in on Friday, with the core of the cold air setting in Friday night. Probabilities of temperatures falling below 28 degrees are high (>90%), with current forecast lows reaching the teens. The complicating factor will be how quickly cloud cover clears out behind the weather system, allowing for radiational cooling. If clouds hold longer, these teens would likely not be achieved.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1027 PM MDT Mon Apr 13 2026

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

A tight, compact shortwave along the western Wyoming border rotates eastward overnight. The leading edge of this shortwave produced a two-hour period of intense snowfall at KJAC, but these are beginning to fade late Monday evening. Isolated snow showers, producing intermittent IFR/MVFR conditions come to an end early in the period as the shortwave fizzles and heads east. However, the now moistened boundary layer could lead to widespread IFR/MVFR ceilings and patchy fog at KJAC overnight and into Tuesday morning. Ceilings gradually rise to VFR after sunrise Tuesday and improve further around midday. A few showers skirt southern Wyoming in the vicinity of KRKS until sunrise Tuesday. All other terminals to be VFR. West-northwest surface wind 12-22kts develops around 19Z/Tuesday at all terminals except KJAC, where a southwest wind 8-11kts begins around midday. All winds decrease between 01Z-02Z/Tuesday. Mountain tops obscured across northwest Wyoming until 20Z/Tuesday.

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

All terminals to be VFR through the period. Surface wind speeds Tuesday are to be much less than those of the previous few days. After a morning lull, westerly wind 15-25kts mixes to the surface at KCOD between 20Z-22Z/Tuesday, with KRIW seeing west-northwest surface wind 15-25kts developing around 23Z/Tuesday. Otherwise, speeds remain 11kts or less at other terminals.

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

RIW WATCHES/WARNINGS/ADVISORIES

Winter Storm Watch from Wednesday evening through late Thursday night for WYZ001-002-012.