textproduct: Western and Central Wyoming

KEY MESSAGES

- A cold front has begun to move across the state this afternoon bringing with it showers, gusty winds, and colder temperatures.

- Rain/snow showers are expected to move into portions of northern and central WY this afternoon/evening. Portions of the Bighorn Basin along with Johnson and Natrona Counties may see a light coating to an inch or two of wet snow by Friday morning.

- Periods of light to moderate snow will continue through late Friday morning over the high elevation mountain ranges of central and northern WY.

- A cooler, and overall more active weather pattern is favored Friday through early next week.

UPDATE

Issued at 123 PM MDT Thu Apr 23 2026

Currently, the cold front is starting to enter the state bringing with it showers and increasing winds. Showers will gradually spread south through the afternoon and evening. A stray thunderstorm or two cannot be ruled out with the best chances remaining across northern WY (10-30%). Otherwise, precipitation amounts continue to decrease especially over central WY such as the Wind River Basin. A shower or two cannot be ruled out with the frontal passage but overall chances for seeing some beneficial moisture once again do not look promising. In other parts of the state, Hi-res models are trying to show a period of moderate precipitation late this evening into the early morning hours Friday over portions of Johnson and northern Natrona Counties. This looks to be the result of some brief upsloping post frontal passage. As a result of this, there is a good chance (50-80%) to see 1 to 2 inches of wet snow mainly along the eastern foothills of the Bighorns. Other locations have not seen much change with mountain snowfall forecasts mostly unchanged. As for the rest of the forecast period, not much has changed with the previous forecast discussion remaining on track. One thing to note is models do continue to show a more unorganized disturbance for the weekend into the start of next week. The potential low that moves through the region is looking more like an open wave likely leading to lesser impacts to the state. There is still time for this to change, but it bears monitoring as nearly all of the state is desperate for moisture.

DISCUSSION

Issued at 254 AM MDT Thu Apr 23 2026

The upper level low that brought precipitation to western Wyoming and widespread wind on Wednesday is now (09Z/3AM) positioned over northeastern Montana. A shortwave rounding this low will traverse the state and provide support for periods of moderate snow across the western mountains, Yellowstone National Park, and the Bighorn Mountains through roughly 11AM this morning. In addition to the snow, widespread wind can be expected. For lower elevations, wind gusts this morning will generally be in the 20 to 35 mph range with the shortwave passage. Higher elevations and wind prone locations have a 60 to 75 percent chance of at least 40 mph winds this morning.

The next "round" of snow, wind, and colder temperatures will arrive shortly after the aforementioned shortwave moves through. Another upper level low, currently over the Canadian province of Alberta, will shift south and "absorb" the current Montana low early this afternoon. As it does so, a shortwave and associated cold front will move south into Wyoming. The cold front is currently forecast to move north to south across the state between 3PM and 9PM today. As it drops south, another round of moderate snow is expected for the western mountains, Yellowstone National Park, and the Bighorn Mountains. The Bighorn Mountains have been added to the Winter Weather Advisory today for snow amounts of 5 to 12 inches through 11PM tonight. There is generally a 60 to 90 percent chance of at least 6 more inches of snow across the western mountains and southwest portions of Yellowstone National Park today, so the Winter Weather Advisory remains in effect. Winter travel conditions can be expected with snow and wind for all western mountain passes and Powder River Pass. There will be some instability (around 200 J/kg, unstable mid level lapse rates, and increased frontogenesis) with the front this afternoon/evening, so some instances of snow banding and thundersnow is possible.

This cold front also brings some precipitation potential and more wind to most low elevations of central and western Wyoming. First, the pressure gradient will continue to tighten early this afternoon bringing widespread 25 to 35 mph winds, with wind prone locations seeing occasional gusts of 50 mph. For the Wind River Basin and Natrona County specifically, the boundary layer remains relatively unsaturated ahead of the front. The wind and dry air (relative humidity around 20 percent) across these areas, will create elevated fire weather conditions early this afternoon. Relative humidity is forecast to be between 25 and 30 percent elsewhere. Additionally, ahead of the front, isolated showers and/or virga and thunderstorms are possible (30 percent) across central Wyoming. There will be moisture accompanying the cold front so there exists a 60 to 90 percent chance of precipitation for all areas east of the Divide and across western Wyoming. For areas east of the Divide, expect precipitation to start first as rain. Because of the Canadian origin of the system, a cold push of air is expected behind the front which will allow for rain to change over to snow late tonight and continue as snow overnight. Most low elevations east of the Divide have a 40 to 80 percent chance of seeing 1 inch of snow by Friday morning. Areas such as northern Natrona County and Johnson County have a 60 to 70 percent chance of seeing 2 inches of snow by Friday morning. The front ultimately stalls along the northern Sweetwater County border, so southern Wyoming can expect to remain dry.

The front will remain stalled roughly along the northern Sweetwater County border on Friday. In the upper levels, the low stalls over the southern Canadian Provence of Saskatchewan with zonal flow, and embedded passing shortwaves over Wyoming. With 700mb temperatures of minus 2 Celsius to minus 10 Celsius, a cool day with light snow or a rain/snow mix can be expected north of the front. South of the front across southern Wyoming, a relatively warm, dry, and windy day is forecast on Friday. Southern Wyoming will be windy due to passing shortwaves aloft and a tight gradient at the surface. Should the front stall farther to the south, southern Wyoming could see some precipitation but the current chances of this occurring are 15 percent.

The front lifts north on Saturday as the upper level low's trough expands to the west and puts Wyoming in more west to southwest flow aloft. Expect Saturday to be the drier and warmer day of the weekend as a brief push of drier air moves in. However, this drier air will not last for long. Ensemble guidance is in consensus that by later Saturday a shortwave trough embedded in the southwesterly flow will approach southern Wyoming and usher Pacific moisture into the Intermountain West. By Sunday, there are indications that an associated 700mb low will traverse across the Wind Corridor region of the state. This is currently not looking to be a major precipitation event by any means. There are still plenty of uncertainties with regards to the exact location, timing, precipitation amounts, and temperatures with this system. However, if this trend continues, many areas could see precipitation on Sunday. Ensemble guidance has a reasonable amount of agreement that more zonal flow will set up over the state with weak embedded disturbances Monday through Wednesday. This indicates that there are more precipitation chances on the horizon for Wyoming next week.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 435 PM MDT Thu Apr 23 2026

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

Snow showers will continue at KBPI/KPNA/KJAC through around 06Z. Models have backed off of some of the precip at KBPI/KPNA, which have aligned better with KJAC having a break in the precip overnight tonight. The next round still noted for around 12Z at KJAC, lasting through the morning hours, with cigs down to around 2000ft. The main snow production should be finished by 18Z, but low to mid clouds will persist through sunset.

KRKS remains well away from any precip, with only midlevel clouds varying through the next 24 hours. Winds will again ramp up during the afternoon Friday, with frequent gusts reaching 40kts.

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

Snow will continue to push southward through 06Z tonight with the cold front. Precip will increase at KCOD/KWRL through this evening, with KCPR seeing rain change to snow by 04Z. Showers will taper off at KCOD/KWRL after 06Z, but showers remain in the vicinity through most of Friday behind the front. KCPR will see cigs approach IFR overnight, with snow showers continuing. KLND/KRIW will be on the edge of snow showers tonight, with light rain switching to light snow around 05Z. Main precip here should end by 10Z, but a few lingering showers are possible again Friday afternoon.

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 Weather Advisory until 11 PM MDT this evening for WYZ001-002-008-009-012-024.