textproduct: Western and Central Wyoming

KEY MESSAGES

- A dry and mild day today with elevated fire weather from Muddy Gap through Natrona and Johnson Counties.

- A Pacific weather system spreads light to possibly moderate snow to the western mountains later tonight.

- Accumulating snow is likely for much of the area from Thursday into Friday, although amounts East of the Divide still have some uncertainty.

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 for now.

The next weather maker arrives in the west in the form of a Pacific cold front and trough tonight across western Wyoming. I again 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 a few things are still uncertain. As lee cyclogenesis develops over Colorado, flow will turn northeastward. This should bring some decent upslope. 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 Big Horn 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. These can really enhance snowfall and it is showing greater than a half of inch of QPF Friday night which could lead to greater than 6 inches of 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 /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 930 PM MST Tue Mar 3 2026

VFR conditions expected for all TAF sites for the entirety of the period. A few to scattered high clouds overnight and into much of Wednesday increasing in coverage after 00Z ahead of the next system. Any precipitation will be into the next TAF cycle or two for west of the Divide for Thursday. Otherwise, an increase in winds for PNA/BPI up to 18kts between 19-00Z with daytime heating. CPR will be strongest picking up after 11Z peaking at 30kts after 16Z before all diminishing after 00Z with radiational cooling. All other sites will remain relatively light 10kts or less.

Please see the Aviation Weather Center and/or CWSU ZLC and ZDV 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

None.