textproduct: Western and Central Wyoming

KEY MESSAGES

- Rain/snow continues to spread east of the Divide overnight and into the early morning hours Friday.

- There remains high uncertainty regarding impacts for locations east of the Divide with a wide variation in snowfall amounts but has trended downward in lower elevations.

- Precipitation dissipates through the day Friday with dry and mild conditions returning to the area for the upcoming weekend.

UPDATE

Issued at 1108 AM MST Thu Mar 5 2026

A few updates to add in terms of the short term forecast. As mentioned in the previous discussion this system is a doozy with impacts east of the divide continuing to be uncertain. The forecast for locations west of the Divide remains mostly unchanged with the previous discussion explaining impacts well. The NBM continues to trend down in terms of snowfall amounts and QPF for many locations east of the Divide. This is likely a result of hi-res models such as the HRRR and NAM showing a disorganized mess as the system moves east of the Divide. The track of the aforementioned 700 MB low remains a mystery. Models continue to jump around on its positioning which can greatly differ impacts. Overall, the trend seems to be lesser chances for 2 or more inches of accumulating snow over portions of central and southern WY. At the moment the best chances for an inch of more of snowfall would be along the Lander Foothills and east towards Casper. Chances of an inch or more of snow over this area ranges from 40 to 70%. Which is a significant drop compared to yesterday at this time. Probabilistic guidance yesterday showed 70 to 95% chance of 2 inches or more over this area. That should show just how much uncertainty and volatility there is in the forecast. There has been a increase in QPF and snowfall across the Cody Foothills and portions of the Bighorn Basin as mentioned in the previous discussion. However, temperatures may hinder impacts as the big push of moisture for this area comes when temperatures are still likely above freezing. So at this moment we will be holding off on issuing any winter highlights for the Cody Foothills. That being said, elevation would play a key role in determining where the best chances for accumulating snow fall would be. Precipitation looks to linger across portions of central and southern WY through the day Friday. Showers dissipate by the evening on Friday with mainly dry and mild conditions returning to the area for the upcoming weekend.

DISCUSSION

Issued at 132 AM MST Thu Mar 5 2026

Nights like this make me want to reach for the antacids and aspirin. With this system, the models have been about as consistent as a cell phone signal over some of the more rural portions of our area. Each run has different wrinkles and new placements of heavier areas of precipitation and tonight is not exception. We will split the discussion into West and East of the Divide for this system.

West of the Divide...As expected, snow held off until shortly before midnight, with Afton now reporting snow as of after midnight and it should be moving into Jackson shortly. For the most part, snowfall amounts in the western mountains look to be in fairly decent shape, with most areas in the advisory range. Both the HREF and NBM ensembles give a greater than 1 in 2 chance of 6 inches of snow over the most impacted areas, the Tetons, Salt and Wyoming Range and southwestern Yellowstone. Models are also fairly consistent in the timing of the heavier snow; one period late tonight with the front, and another this afternoon / evening with the following trough / upper level low passage. In the valleys, amounts have come up in the Star Valley somewhat, but with less than a 1 in 3 chance for 4 inches or more we held off on any highlights. Snow should taper off later tonight with only a few snow showers on Friday.

East of the Divide and Sweetwater County...Uncertainty increases substantially here, hence the source of my headache and indigestion. As for most of the daylight hours, temperatures will cool with the front. However, most guidance has slowed with the progression of the showers, so many areas, especially south of the Owl Creek and Bridger range, may end up largely dry through the daylight hours. The mountains will see some showers earlier though. A few spots may see a change over the snow later this afternoon, but the warm ground should melt the snow on the roads initially.

The fun starts tonight. There is one concerning thing on a couple of model runs. It is showing a weak 700 millibar circulation moving into northern Wyoming. This could lead to a bit more snow across the northern Bighorn Basin than initially thought. There are some things working against it though. One, there is little jet support, as the core of the jet is further east. In addition, usually there is an Arctic boundary and that is not the case. For now, we upped PoPs and QPF somewhat. The day shift will have to watch this in case the trend continues. We may need an Advisory if things continue to trend wetter. Ensemble guidance gives less than a 1 in 8 chance of 2 inches or more, but I don't trust it. Things could be elevation based here, with higher elevations, like Meeteetse, Cody and Powell possibly seeing more snow than a place like Greybull or Worland. The time to watch would be after 9 pm tonight through Friday morning. The area of greatest concern would be Cody to Meeteetse, there north to northeasterly flow could bring some upslope enhancement. Another concern is Buffalo, but more for impacts. Snow tonight may combine with wind gusting possibly to 40 mph to bring difficult travel conditions for a time. Ensemble guidance only gives a 1 in 10 chance of 2 inches or more, so no highlights yet. But again, this has to be watched.

Elsewhere, the trend has been later and downward. Most guidance pushes the start of the snow later, maybe not until closer to midnight for central Wyoming. Amounts have also come down by about 20 percent. However, there continue to be differences in placement of heavier areas of snow. As a result, the most impactful time the snow looks to be between midnight and noon on Friday. We have left the advisories alone for now, but right now I would favor the lesser amounts. The generally pattern of northerly upslope is there, with the highest amounts from Lander to Casper. This area still has a decent area with at least a 1 in 2 chance of 3 inches or more according to the ensemble guidance. I initially thought of possibly canceling a couple of zones, but given the flip flopping models, we left everything alone. It is the same story for Sweetwater County. Amounts still look to be in the advisory range, especially east of Rock Springs with at least a 1 in 2 chance of 3 inches of new snow. The time of maximum impact here would be during the day on Friday. In all areas, snow should taper off by Friday evening and end shortly after midnight Friday night.

Quiet weather then returns for the weekend as ridging builds over Wyoming. Things look dry except for a few showers in the western mountains. Saturday looks like a cool day, followed by warming on Sunday as flow turns west to southwest and the snow continues to melt. The next potential weather maker will be a front moving in from the north, more than likely Monday night or Tuesday. Models are split on whether it will make it or not. As for temperatures, above normal is once again likely for much of the week, except for maybe northern Wyoming depending on how far south the front can get.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 930 PM MST Thu Mar 5 2026

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

VFR conditions expected for the entirety of the period. Showers in the vicinity of JAC/PNA over the higher elevations to start but soon to pass to the southeast. RKS will see shower activity between 13-17Z with BPI/PNA remaining dry. Otherwise, lower ceilings will slowly rise through the period to the mid levels by 18Z and upper levels after 00Z. Winds breezy at BPI with all other locations relatively light through the period. Mountain obscuration expected through Friday morning.

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

MVFR conditions expected at COD/CPR with cold frontal passage early in the period with showers expected around on and off on station. LND/RIW best chance for shower activity after 07Z through before sunrise Friday morning. All other sites will have low but VFR conditions. Winds increase at CPR/RIW through much of the daylight hours up to 25kts with other sites 10kts or less. Ceilings rise to the mid levels after 18Z scattering to the upper levels after 00Z northwest to southeast. Mountain obscuration expected through early afternoon before improving there after.

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 MST this evening for WYZ002-012-024.

Winter Weather Advisory until 11 AM MST Friday for WYZ007>009.

Winter Weather Advisory until 5 PM MST Friday for WYZ014-015.

Winter Weather Advisory until 5 PM MST Friday for WYZ028>030.