textproduct: Western and Central Wyoming

KEY MESSAGES

- Little to no precipitation chances through the weekend as high pressure brings warm and dry weather to the area.

- The next weather system is possible Tuesday into Wednesday. Early indications are for western mountain snow and widespread, very gusty winds.

UPDATE

Issued at 1041 AM MST Fri Dec 12 2025

No major changes to the forecast for today. The potent cold front that swept through last night has dropped temperatures significantly across Johnson County, as well as the northern Bighorn Basin, where 24-hour temperature differences are 30 to 50 degrees lower. The front also made it into the Casper area, with temperatures 20 to 30 degrees lower than yesterday. Cooler temperatures in these areas linger through tomorrow, but it begins to warm Sunday.

Looking ahead at the Tuesday/Wednesday system, EFI/SOT (weather guidance to determine the potential significance of a weather event) highlights Wednesday for precipitation in the western mountains. It also significantly highlights wind gusts over the entire area Tuesday and Wednesday, with 70th to 95th percentiles and SOT values of 1. So, this will be the system to watch in the coming days, mainly for the wind threat.

DISCUSSION

Issued at 1117 PM MST Thu Dec 11 2025

The main concern in the short term will be the expected snow and travel impacts across northern Wyoming, especially from the Bighorn Range and eastward where the Winter Weather Advisory is in effect. Snow is now spreading into the area and will continue through the night before tapering off later in the morning. As was noted by the day shift, the main concern will not be snowfall amounts, as they should remain below advisory criteria. The main concern is icy roads from the rapidly falling temperatures following the warm temperatures today, (it was in the 50s and 60s) and a possible flash freeze. We will continue the Advisory as is for now. The only other location with a greater than a 1 in 3 chance of 3 inches or more is the northern Absarokas, and there are few impacts in that location. Otherwise, the challenge today will be temperatures and how far south the front can reach. Johnson County and the northern Bighorn Basin will be much cooler, with the high in Buffalo possibly 40 degrees colder than yesterday. It will remain milder further south though as the front would likely not make it. It should be a bit cooler than yesterday, but still well above normal for mid-December. We will continue to have some gusty breezes at times as well with the jet close to the area, but nothing like the wind we have seen the past few days.

Zonal to flat ridging then controls the weather through the weekend and into Monday. This means a continuation of above normal temperatures and breezy conditions. It is possible we could see more high temperature records fall, especially on Sunday and Monday following the brief cooldown on Friday and Saturday. There will be a gusty wind continuing in the favored areas, but high wind is not expected through that time period. The only fly in the ointment through this period will be one last piece of energy that could bring some snow showers to Johnson County on Saturday, but any amounts would be light and impacts minimal to none.

The next likely weather maker will be in the form of a Pacific trough and cold front that approaches Tuesday and Wednesday. Given the zonal flow across the area, impacts look similar to this weeks situation with most of the precipitation across western Wyoming with the orographic enhancement. Models are split on if any precipitation makes it east of the Divide though. There is higher confidence in strong to potentially high wind, with most guidance having an 140 to 160 knot jet over Wyoming from later Tuesday through Thursday. Details are obviously impossible to nail down this far out though. We are highly confident on above normal temperatures continuing across most of the area through most of the next seven days.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 406 PM MST Fri Dec 12 2025

MVFR ceilings continue at KWRL late this afternoon. Recent trends favor the persistence of this later than previously expected, and we now have low clouds through 03Z there. Otherwise, remaining terminals should stay VFR through the period as low clouds depart. The main aviation concern will be wind, most notably at KCOD, KCPR, KRIW and KRKS which will see southwest gusts of 20 to 25 knots for much of the period.

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

None.