textproduct: Western and Central Wyoming

KEY MESSAGES

- Spring-like weather across the Cowboy State today with mild temperatures and dry conditions.

- A weather system begins to enter the region late tonight bringing snow to western WY and gradually spread east of the Divide Thursday afternoon/evening.

- Accumulating snow is forecast to occur across the low and high elevations east of the Divide Thursday into Friday. The greatest snowfall chances look to be across parts of central and southern WY.

- Snow dissipates Friday with a gradual return to warm and dry conditions over the weekend.

UPDATE

Issued at 119 PM MST Wed Mar 4 2026

Multiple updates to the short term forecast in regards to the incoming weather system. Overall, precipitation begins to move into western WY late Wednesday night into the early morning hours Thursday. Periods of moderate to heavy snowfall look to occur across the western mountains from YNP south into the Wyoming/Salt River Ranges. Lower elevation western valleys will see some light snowfall but impacts look minimal at this time. Precipitation gradually makes its way east of the Divide during the afternoon/evening on Thursday. There is some discrepancies among hi-res models regarding timing. It is possible that precipitation takes a little longer to begin with some models suggesting a late evening start. Regardless, due to warm temperatures precipitation across lower elevations will likely first fall as rain or a mix before transitioning over to snow later in the evening. Currently, the favored locations for the greatest snow accumulation looks to be along the Lander Foothills and from Casper west to the county line. Portions of Sweetwater County from Rock Springs east to Wamsutter look to be another favored area as well. Higher elevations east of the Divide, such as the eastern Wind River Mountains, Casper Mountain, the Owl Creek and Bighorn Ranges, as well as the Rattlesnake Hills look to see favorable dynamics for 6 or more inches of snow accumulation. Winds do look to increase some Thursday into Friday which may create some blowing snow and difficult driving conditions at times. Precipitation gradually dissipates through the day Friday with gradual warming expected to occur over the weekend.

Now for a more detailed examination of the impacts associated with the incoming system. Starting across western WY first. As mentioned earlier, precipitation begins to move in late Wednesday into the very early morning hours Thursday. Hi-res models have picked up on some heavier precipitation occurring during the morning and early afternoon hours Thursday. The heaviest snow will remain along the highest peaks of the western mountains with amounts ranging from 6 to 12 inches. Lower elevations of the western valleys look to see light accumulations with amounts ranging from 1 to 3 inches. The forecast becomes pretty tricky east of the Divide with models showing a wide variety of outcomes. These outcomes range from little to no precipitation to widespread heavy precipitation. At this time confidence remains for locations that favor northerly/northeasterly flow. This would include the Lander Foothills, eastern slopes of the Wind River Range, Rattlesnake Hills, Casper Mountain, and portions of Natrona County. Probabilistic guidances supports this with chances for 3 inches or more ranging from 60 to 80% for locations from the Lander Foothills to Casper. Chances drop to around 20 to 40% for snow accumulation of 6 or more inches. Other portions of the Wind River Basin are looking to see lesser amounts with only a 20 to 50% chance for 2 or more inches. The I-80 corridor from Rock Springs to Wamsutter is another area with solid chances of 50 to 70% to see 3 or more inches of snow. As mentioned earlier, there is a lot of volatility among models when it comes to possible storm total snow accumulation. The overall picture at this time is one with a low floor and high ceiling meaning amounts range greatly. At this time there is enough confidence to issue Winter Weather Advisories across parts of the State. Starting late tonight Winter Weather Advisories go into effect across the western mountains including YNP through Thursday evening. The Absarokas, Owl Creek, and Bighorn Ranges see Winter Weather Advisories go into effect Thursday through Friday morning. Portions of central and southern WY see Advisories begin late Thursday through Friday afternoon. Depending on how things pan out over the next 12 to 24 hours, there is the possibility to see more winter highlights or even some current advisories being upgraded to warnings.

DISCUSSION

Issued at 119 AM MST Wed Mar 4 2026

Things look fairly active over the next three days. Today will be the least active. For most of the area, it will be a nice late winter / early spring day with a continuation of well above normal temperatures and a mixture of sunshine and high clouds. The one issue will be fire weather. This looks be mainly from Muddy Gap to Natrona and possibly Johnson Counties. For now, it looks largely elevated and not critical. Muddy Gap to Casper will have the gusty wind, with gusts over 30 mph. However, humidity will be generally in the 20 to 25 percent range. In Johnson County, humidity will fall to around 15 percent. However, the wind will remain light to moderate. So, we will stick with elevated to near critical fire weather conditions for now.

The next weather maker arrives in the west in the form of a Pacific cold front and trough tonight across western Wyoming. Again I assert that the forecast is the fastest precipitation could arrive, and most areas should be dry until around midnight. Snow will begin moving across the area late tonight and into Thursday. The system is showing some signs of spitting though and the best forcing looks to remain just north and west of Wyoming, over northeastern Idaho and southwestern Montana. This should help limit amounts somewhat. The HREF ensemble only gives a greater than 1 in 2 chance of over 6 inches of snow over two locations, the higher elevations of the Tetons and southwestern Yellowstone. The former is where they want snow and the heaviest is away from the passes and the latter location has nothing but bears and moose this time of year. Amounts drop further south away from the best forcing. The chance of 4 inches in the valleys is basically zero, and precipitation may start as rain before changing over. The snow will also fall over around a 36 hour period, but the heaviest would be on Thursday with leftover showers in Friday.

As we move to east of the Divide and Sweetwater County, things look relatively uneventful through most of Thursday. Most of the precipitation is anafrontal, so the cold front will move through in the morning, bringing cooler temperatures. A few showers may develop in the afternoon on Thursday, but most locations should be largely dry through sunset. Precipitation should really increase Thursday night and continue into Friday. We have a decent idea of a few things and others are still uncertain. As lee cyclogenesis develops over Colorado, flow will turn northeastward. This should bring some decent upslope flow to central portions. As a result, we are fairly confident that the highest snow totals would be from Riverton to Lander and Casper, the eastern slopes of the southwestern Absarokas and into Sweetwater County, where there is at least a 1 in 2 chance of 3 inches of snow or more. As for the possibility of 6 inches, the chance continues to be low right now, at most 1 out of 3. As for warning level criteria, the only spots right now would be the eastern Wind River Range, but away from the passes, and possibly the top of Casper Mountain. The least snow would be in the eastern Bighorn Basin, where northeast flow would downslope off of the Bighorns. There is one fly in the ointment though. The 00Z GFS shows a weak 700 millibar low moving over the Wind River Basin. This could really enhance snowfall and the GFS is showing greater than a half of inch of QPF Friday night, which could lead to greater than 6 inches of snow accumulation. The other models don't have it though. The chance is there, but it is not the most likely scenario at this time.

Most guidance shows the heaviest snow Thursday night. The best forcing moves away by Friday morning, but lingering moisture and cyclonic curvature will keep some light snow going into Friday before ending at night as ridging builds back over the area. High pressure should then bring dry weather for the weekend. The next system in the form of a cold front may bring the next chance of precipitation at the start of next week.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1055 AM MST Wed Mar 4 2026

VFR conditions are anticipated at all terminals through the first half of the period. Elevated southwest winds will be seen through the day at KCPR with gusts to around 30 knots. This wind will decrease at sunset. High clouds will increase this evening ahead of the next system. This is expected to return MVFR conditions to KJAC after 08Z as snow moves into western Wyoming. The current forecast shows an improvement at KJAC after 12Z as this first round of snow becomes more confined to the mountains around the valley. However, trends will need to be watched closely today as there is also guidance suggesting worsening conditions at KJAC after sunrise Thursday; confidence on impacts is notably low at the moment. Regardless, frequent mountain obscurations are expected in the vicinity of KJAC after 06Z Thursday. Mid cloud decks will move over KBPI and KPNA near the end of the period.

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

FIRE WEATHER

Issued at 119 AM MST Wed Mar 4 2026

A combination of a gusty southwest wind and relative humidity falling to around 20 percent will bring elevated to near critical fire weather from Muddy Gap through Natrona County this afternoon. Across Johnson County, humidity will fall into the teens, but wind is expected to remain light to moderate.

RIW WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory from 11 PM this evening to 5 PM MST Thursday for WYZ001-012-024.

Winter Weather Advisory from 5 AM to 11 PM MST Thursday for WYZ002.

Winter Weather Advisory from noon Thursday to 11 AM MST Friday for WYZ007>009.

Winter Weather Advisory from 5 PM Thursday to 5 PM MST Friday for WYZ014-015.

Winter Weather Advisory from 8 PM Thursday to 2 PM MST Friday for WYZ018-020.

Winter Weather Advisory from 8 PM Thursday to 5 PM MST Friday for WYZ019-022.

Winter Weather Advisory from 11 PM Thursday to 5 PM MST Friday for WYZ028>030.