textproduct: Western and Central Wyoming

KEY MESSAGES

- Strong gusty winds will continue tonight after a cold front moved through areas east of the Divide earlier this evening. Temperatures will continue to drop through the night.

- Isolated snow showers may be possible across areas east of the Divide this evening through midnight.

- Dry, cold and windy conditions will be in place Friday, with high temperatures 20 to 30 degrees colder east of the Divide. Wind gusts of 30 to 50 mph will be widespread, with the higher gusts occurring over Johnson County.

- Mild temperatures and mainly quiet conditions return for the weekend through the first half of next week.

UPDATE

Issued at 722 PM MST Thu Jan 15 2026

The cold front moved through much faster than expected, reaching the Continental Divide around sunset this evening. Winds have come down a bit in the wake of the front over northern portions. Gusts of 60 to 77 mph occurred here earlier this afternoon around 2PM and 3PM. Gusts around 50 mph are still occurring through eastern portions of the Bighorn Basin, Johnson County and Natrona County. Areas of snow will also continue across the I-25 Corridor this evening, ending around midnight. Reductions in visibility and slick roads will be the main impacts. THe gusty winds and falling temperatures will be the main hazard tonight, with lows in the teens and 20s for most locations. The western valleys will drop into the single digits once again.

DISCUSSION

Issued at 202 AM MST Thu Jan 15 2026

Satellite water vapor imagery at 09Z shows three distinct features that will influence the weather across Wyoming through Saturday. The first is the upper level ridge centered over northern California, keeping northwesterly flow aloft. The second feature is a weak disturbance embedded in the northwest flow traversing over southern Montana as of 09Z. The third feature is potent shortwave trough, with limited moisture, over eastern Washington. The weak disturbance, the second feature mentioned, will shift into northern Wyoming early this morning through roughly 10AM. This disturbance will provide support for gusty 25 mph to 35 mph winds across northern Johnson County and wind prone high elevations. Behind this disturbance, winds aloft become more northerly and the surface pressure gradient will be tightening ahead of an approaching cold front. Thus, a windy afternoon is in store for much of the area with widespread gusts of 15 mph to 25 mph across many low elevation areas. Gusts of 30 mph to 45 mph are forecast across north/northwesterly wind prone locations such as northern Johnson County, the Cody Foothills, portions of Natrona County, and high elevations.

The aforementioned cold front and potent shortwave trough will traverse, north to south, across the state between 3PM and 11PM today. Along and behind the front, winds will increase even more, especially across northern Johnson County, as a strong, northerly upper level jet positions itself over the state. There is high confidence (90%) that the strongest winds will occur over Johnson County late this evening through at least Friday evening due to a 60kt to 70kt 700mb wind maximum directly over this area. For Johnson County, sustained winds of 25 mph to 40 mph and gusts around 60 mph are expected (90%+ chance) from 3PM this afternoon through Friday evening. Thus, the High Wind Watch has been upgraded to a High Wind Warning valid from 3PM Thursday through 5PM Friday. Another area of interest during this time frame is the Bighorn Basin, given the favorable northerly flow. Northerly winds of 20 mph to 35 mph, with 75% chance of gusts of 40 mph, are forecast behind the front and on Friday. A gust of 50 mph is not completely out of question (25% to 30% chance), however, any gusts above 50 mph are unlikely given the 700mb wind maximum is farther east. On Friday, there is an 80% chance of 40 mph gusts across Natrona County. Most other locations across the state will have a windy Thursday evening with and for a few hours behind the front with gusts between 25 mph and 35 mph. Star Valley and Jackson Hole Valley will likely (90%+ chance) be spared of any gusts at all between now and Friday evening.

The second story with the cold frontal passage is the accompanying colder, near season temperatures. High temperatures today/Thursday are forecast to be 15 to 25 degrees above normal, especially east of the Divide, with highs in the upper 40s to 50s. At sunset this evening, mean 700mb temperatures are forecast to be anywhere from - 1C to -6C. By sunrise on Friday, behind the front, forecasted mean 700mb temperatures drop to -9C across southwest Wyoming to near -20C across northeastern portions. This means temperatures Friday morning will be in the single digits across west Wyoming and teens to low 20s (Fahrenheit) elsewhere. High temperatures on Friday are forecast to be 20 to 30 degrees colder compared to this afternoon's / Thursday's high temperatures, especially east of the Divide. However, Friday's temperatures will be more representative of "normal" mid January highs.

The third and final story with the cold front are the light precipitation chances (20% to 40%) with and behind the front across Johnson and Natrona Counties, the Bighorns, Casper Mountain, and other high elevations east of the Divide. Precipitation will begin as light rain across northern Johnson County before transitioning to light snow. Accumulations will be light as this is not a very saturated system. There is a 70% chance of 0.5 inches and a 40% chance of 1 inch across northern Johnson County. Other low elevation areas of Johnson and Natrona Counties will be lucky to see 0.5 inches.

A windy night can be expected Friday night into Saturday with the upper level jet still overhead. However, we have opted to not extend the High Wind Warning into Friday night at this time due to weakening 700 mb winds. There is a good consensus that the west CONUS ridge will remain in place from Sunday through at least mid next week, ultimately keeping most of the area precipitation free. Temperatures over the weekend are forecast to in the 30s and 40s. Guidance has been hinting that a weak, mostly dry cold front will traverse the area late Sunday into Monday. This front will likely only bring Monday's high temperatures down a few degrees compared to Sunday. There is a reasonable amount of confidence (around 60%) that mild temperatures will return on Tuesday. There is early indication that the west CONUS ridge will shift east by Thursday and bring a return of westerly flow. This would mean that the region will be able to tap into Pacific moisture and potentially bring a return of snow to western Wyoming by late next week.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 918 PM MST Thu Jan 15 2026

Brief marginal MVFR conditions will be possible at KCPR, KRIW and KLND to start the forecast, but will quickly improve back to VFR by 08Z. Any snow is also expected to end by this time as well. Gusty north winds will continue, with gusts of 25 to 35kt through 00Z. Winds will decrease for most sites, with sustained winds of 10 to 15kt.

At KJAC, the low clouds are staying to the north of the terminal currently. However, the north winds could help push these through the rest of the night. There is also a 30% chance for MVFR conditions. So, have left the mention of low clouds in the forecast.

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

High Wind Warning until 5 PM MST Friday for WYZ010-011.