textproduct: Western and Central Wyoming

KEY MESSAGES

- A cold front moves in tonight, bringing cold temperatures to the area for Friday. Coldest temperatures occur Saturday morning, with lows around and below 0 degrees.

- Light snow is possible, mainly east of the Divide Friday into Saturday. Up to 2 inches is possible for portions of the Bighorn Basin, Johnson County, and Natorna County, with lesser chances elsewhere.

UPDATE

Issued at 1127 AM MST Thu Jan 22 2026

No changes to the overall message for the next few days. A cold front moves in tonight, ushering in colder temperatures for the end of the week. Winds do not look to be a major concern, with gusts maybe topping around 30 mph with frontal passage for favored areas like the Bighorn Basin and Natrona County, mainly the western portion of the county. Breezy winds 15 to 20 mph become more widespread for Friday afternoon.

For temperatures, the coldest period will likely be Saturday morning lows (though Friday is also notably colder). There is a widespread 60 to 100 percent chance for Saturday morning lows to be 0 degrees or less, with the warmest temperatures across southern Sweetwater County. For the coldest areas, there is a 20 to 40 percent chance for below negative 10 degrees in the Bighorn Basin and a 40 to 60 percent chance for Johnson and Natrona Counties. Localized cold prone locations (like near rivers and in low spots) could be in the negative teens for these locations. Cloud cover and snow potential will be the greatest influence in these temperatures, adding some uncertainty with the current temperature forecast. Wind is not a great factor Saturday morning, but a light breeze around 10 mph in Johnson and Natrona County could have feel-like temperatures in the negative teens.

For snow, greatest accumulations are east of the Divide, mainly the eastern Bighorn Basin and Johnson/Natrona Counties. Latest guidance would suggest 40 to 60 percent chance for at least half an inch in the Bighorn Basin and 60 to 70 percent chance for the lower elevations of Johnson and Natrona Counties. Higher-end amounts of 2 inches or more is possible for Buffalo (20 percent chance) and Casper (40 percent chance). With the expected north-northwest flow, southern Casper will likely see more snow than northern parts.

DISCUSSION

Issued at 237 AM MST Thu Jan 22 2026

For the most part things are quiet at the humble Riverton weather abode as high pressure is bringing dry, quiet and for the most part seasonably cold weather tonight. We have two questions tonight that we are pondering for the forecast as we listen to classic rock tonight (two Gen Xers working tonight). The first is how much snow we will get over the next three days, and the second, more important question, is how cold will it get as we have the coldest air of the season moving in for the weekend and will people be Stone Cold, Cold As Ice or So Cold (I threw in Breaking Benjamin for the Millennials). We will do something different and address these individually.

We will start with snow. Dry conditions are expected today, but the next cold front (the third we have seen this week) will cross the area tonight and into Friday. And, I'm going to sound like a broken record, with the Arctic origins of the air, it has little moisture to work with. As a result, snowfall amounts are expected to be light. In the deterministic model realm, the ECMWF brings a fairly broad area of light QPF (less than a tenth of an inch) across most areas east of the Divide. The GFS is much drier with only some light snow showers across areas east of the Divide. Then we transition into the probabilistic realm of ensemble guidance. The snow is still expected to be of the anafrontal variety, falling behind the front. And with the northerly flow behind the front, the heaviest snow (a relative term with this system) would fall in the favored northerly upslope locations. This looks to be further east as well, generally around Casper and from Thermopolis and eastward into the southeastern Bighorn Basin. Even here, the chance of over an inch of snow in the lower elevations is only 1 out of 2. When we bump the totals to advisory level (3 inches), the only possible area is around Casper, where there will be a bit of right rear quadrant jet energy to enhance lift a bit. Even here, the chance is only 1 out of 5 at the most. This, plus the fact the cold air will ooze in rather than move in quickly, wind should not be too strong. So, no advisories here. Elsewhere, the chance of an inch of snow is less than 1 out of 10. This round of snow should end Friday night. After a dry Saturday, the fourth and last front will move into the area Saturday night. This system is even drier and will bring even less snow, with only some showers expected and any accumulation expected to be light.

The main story looks to be the cold air, the coldest of the season. One disclaimer here, this will not be a record breaking cold outbreak. Temperatures will generally be 10 to 15 degrees below normal as the core of the cold air will remain well to the east, over the Northern Plains and Great Lakes, with Wyoming seeing more of a glancing blow. The 700 millibar temperatures will be generally down to around minus 21C, as opposed to the minus 30s further east. Friday will be the coldest day in a long time for areas east of the Divide, with highs remaining in the teens and single digits. As of now, it is looking more likely that many areas will see lows in below zero east of the Divide, with most areas having at least a 4 out of 5 chance. There are still a couple of wild cards though. One is if the clouds don't clear quickly enough, keeping temperatures up just a bit. The other is snow cover. Areas further west may not have any snow cover, keeping temperatures a bit warmer. The coldest temperatures may end up being in Natrona County, where snow cover should be the deepest, aiding in cooling. Here, there is a 2 out of 5 chance of lows lower than minus 10. As for cold highlights, don't think they are needed now since minus 20 is not expected and the wind should be fairly calm. Saturday looks cold as well.

The cold should not last though, as the cold air moves to the east as flow turns more northwesterly and westerly. A slow moderation begins on Sunday, but should really be felt on Monday as a weak shortwave approaches and mixes out the atmosphere. Temperatures should return to above normal levels again on Monday. The forecast gets muddier after that, but no Arctic air is expected as we had toward the end of January.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 930 PM MST Thu Jan 22 2026

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

BKN-OVC FL100-180 will be in place for much of the area and progress southward through 13Z. these clouds decks will drop to around FL070 from north to south through this time frame. Lower ceilings will lead to mountain obscurations over portions of Yellowstone and the Absarokas. Conditions are expected to remain dry through the TAF period, along with light winds (11kt or less).

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

MVFR conditions have developed from KCOD to KCPR, with light possible. The best chances look to occur by 14Z, with a 30% chance for IFR visibilities between 15Z and 18Z. MVFR ceilings will be common across the Bighorn Basin by 12Z, with a 30% chance for light snow between 15 and 18Z also for KCOD. Ceilings are expected to stay VFR at KRIW/KLND through the period. Mountain obscurations will be common over the Bighorns and Casper Mountain, with improving conditions as clouds begin to clear from north to south toward the end of the TAF 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.