textproduct: Western and Central Wyoming

KEY MESSAGES

- Light mountain snow and valley rain will continue across western Wyoming through this evening. Winter travel conditions are possible over mountain passes.

- Precipitation chances (50-80%) spread to southern Wyoming tonight and then east of the Divide on Monday. A few thunderstorms are expected across the area Monday afternoon.

- Above normal temperatures persist through midweek, with the next chance for widespread precipitation coming Wednesday night and Thursday. Elevated fire weather conditions are likely ahead of this system on Wednesday.

UPDATE

Issued at 1234 PM MST Sun Mar 1 2026

Snow is beginning to fall across western Wyoming late this morning. This will continue through this evening across the mountains, with light rain falling in the western valleys. Snow accumulations have not changed much, with most of the snow focused on the Tetons which will see up to 6 inches or so through this evening. Overnight the bulk of the precipitation shifts a little farther south across Lincoln and Sublette counties as a reinforcing shortwave arrives. This will be followed by the arrival of the midlevel trough Monday afternoon. This will help kick off some afternoon convection across southern and central Wyoming before the low moves across the area in the evening. This will lead to a period of northerly upslope flow east of the Divide between 00-12Z Tuesday, with a quick shot of decent moisture for central Wyoming. One thing that has changed with this update is that forecast rain accumulation for Fremont and Natrona counties has increased for this period Monday night, most notably near the slopes of the mountains.

DISCUSSION

Issued at 134 AM MST Sun Mar 1 2026

After multiple days of strong and dry northwesterly flow aloft, zonal flow has set in over the Intermountain West. 08Z water vapor imagery shows an area of Pacific moisture coinciding with a shortwave over western Nevada. As an upper level low begins to move into northern California today, this vorticity maximum and moisture will traverse east and support precipitation chances across western Wyoming. Today, precipitation chances are expected to be confined to areas west of the Continental Divide due to a weak boundary positioned along the Divide. Precipitation is forecast to begin late this morning. Expect temperatures today to be slightly cooler than Saturday due to increased cloud cover.

Snow is expected for the western mountains, with the highest amounts across the Tetons due to favorable orographics. Through early Monday morning, there is a 75% to 90% chance of 3 inches of snow and a 30% to 60% chance of at least 6 inches of snow. The higher end of that range (6+ inches of snow) is largely confined to elevations above 9,000 ft MSL across the Tetons. So, expect widespread snow amounts for western mountains to be in that 3 to 5 inch range. For the western valleys, especially Jackson Hole, there is a bit more uncertainty in precipitation type today. Current thinking is that light precipitation will start off as snow late this morning and transition to rain as temperatures near the surface warm early this afternoon. To further support this rain forecast, mean wet-bulb temperatures are around 35F-36F, precipitation rates are forecast to be relatively light, and model soundings are indicating that the greatest saturated layer will be below the dendritic growth zone/DGZ (-10C to -20C). This does not mean that there couldn't be times of a rain/snow mix, but any accumulations today will be close to zero. However, should the precipitation rates increase and overcome the warmer temperatures and more saturation occurs in the DGZ, more snow could occur.

On Monday, the aforementioned low that moves onshore today, will shift east into the northern Great Basin and bring more Pacific moisture with it. As it does so, the surface boundary along the Divide will begin to fizzle out and allow for moisture to spread east. As a result, more widespread precipitation is expected on Monday. Precipitation will stay as snow across the the mountains and as rain for low elevations due to temperatures remaining well above freezing. Across the western valleys, similar conditions and uncertainties will be present, so light snow with minimal accumulations is not out of the realm of possibility (30% chance). With moisture spreading east, the Wind River Mountains look to be the winner for the higher snow amounts on Monday. Saying higher snow amounts is a bit generous as there is only 30% to 60% chance of 4 inches of snow and a 20% to 40% chance of 6 inches of snow, with the higher amounts being confined to elevations above 10,000 ft MSL. The upper low will traverse east across the southern Wyoming border late Monday into Tuesday and take the moisture with it.

Tuesday and most of Wednesday are on track to be mostly dry with above normal temperatures. If you have been enjoying high temperatures in the upper 40s to around 60, be sure to take advantage of it Tuesday and Wednesday. On Wednesday, a longwave trough and an associated cold front is forecast to move onshore the Pacific Northwest and traverse east into the region by late Wednesday. The surface pressure gradient is expected to tighten and bring breezy to windy conditions to portions of central Wyoming. This wind combined with dry conditions could creates elevated to near critical fire weather conditions. However, confidence in fire weather conditions is rather low due to Monday's rain potential across central Wyoming.

There is a reasonable amount of agreement among model guidance that the trough and associated cold front will traverse the region sometime in the late Wednesday/Thursday timeframe. This system is currently forecast to have both moisture and colder air with it so there is potential that some low elevations could see some light snow. Exact details on snow amounts with this system are fuzzy due to differences in the evolution and timing of the trough. Although this system is looking to also bring colder air, that colder air is forecast to bring temperatures closer to normal for early March. For context, normal high temperatures for early March east of the Divide are in the mid 40s and in the upper 30s west of the Divide.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 355 PM MST Sun Mar 1 2026

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

A range of VFR to possible LIFR conditions through the period. Snow and rain will continue through the period, with low clouds in place. Precipitation will be showery, so expect times off worsening conditions within prevailing groups. The worst conditions are at KJAC, with prevailing MVFR to IFR conditions through most of the period. A round of showers (and possible thunderstorms) occurs Monday afternoon, with precipitation chances lingering past the end of the TAF period.

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

VFR conditions prevail overnight and into Monday morning. As a weather system moves through, a round of showers (and possibly thunderstorms) occurs Monday afternoon. These showers could bring brief MVFR to IFR conditions associated with rain and/or snow, as well as sudden gusty winds. Rain chances continue past the end of the TAF period, as precipitation mode shifts from showery convection to upsloping overcast (with some showery elements).

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.