textproduct: Western and Central Wyoming

KEY MESSAGES

- Scattered showers early Tuesday become more widespread into the afternoon with a full changeover to snow overnight into Wednesday morning as temperatures drop.

- Winter Weather Advisories are in effect for the Green Mountains to eastern Sweetwater County due to light accumulating snow and gusty winds up to around 35 mph.

- Freeze Warnings are in effect for lower elevations east of the Divide for Wednesday morning, as low temperatures are in the 20s. - Dry and warming trend into the weekend and next week.

UPDATE

Issued at 1256 PM MDT Tue May 5 2026

Today's weather system is mainly on track. One point of focus with this update is snow potential around the Lander area. Upper-level dynamics and favored flow has the potential to bring heavier precipitation to the Lander area late this afternoon and into the evening. Some hi-res models are depicting snow totals up to around 8 inches, though this scenario seems unlikely (10% chance or less). A more realistic estimate may be 2 to 4 inches, which would occur in a fairly quick time period this evening. One additional thing to note is that there will likely be a steep snow amount gradient from Lander town to the mountains, so amounts may quickly change from 1 inch totals north of town to like 6 inches towards Sinks Canyon. The majority of snow should end by midnight, with light lingering snow possible through around sunrise. Otherwise, highlights remain, with a combination of snow and wind bringing minor impacts to I-80 in Sweetwater County and northward to South Pass and around Jeffery City.

DISCUSSION

Issued at 200 AM MDT Tue May 5 2026

Increasing cloud cover pushing in from the north as depicted on IR. L/W trough extends with a positive tilt northeast to southwest to the upper level low across the Sierra Nevadas. This has given way to increasing divergence aloft through northern Utah to southern Wyoming as the low deepens with models having it embedded into L/W pattern. The PFJ becomes contorted across this area with much of the PVA anomaly extending across southern portions of the CWA and points east into the High Plains. As such, winter weather advisories have been added across the Green Mountains and eastern Sweetwater County for later Tuesday evening into Wednesday morning as this trough pushes northeast. Winds will be the main driver with this area seeing gusts up to 30 to 35 mph likely creating a crosswind across I-80 and Highway 287 through Jeffrey City to Muddy Gap. Likely snow amounts won't be much but expecting around 2 to 3 inches (60-70% confidence) indicative of some blowing snow to hinder visibility in these areas.

Otherwise, ongoing shower activity through southern Bighorn Basin into eastern portions of Fremont County. Models have pushed back the onset of more widespread precipitation, but CAMs are not handling this very well and thus, showing PoPs to QPF being well overdone with the NBM runs. What precipitation is ongoing looks to mix in with, or change over to, snow through sunrise Tuesday morning but not expecting an accumulation at this point in time to hinder morning commutes with temperatures still above the freezing mark. With ample cloud cover throughout the day and reinforcement of cooler air, expect temperatures to show not much of an afternoon warmup, struggling to break the 40 degree mark for many basins east of the Divide.

Better chances for precipitation changing over to snow Tuesday evening after sunset and overnight as the aforementioned upper level low becomes progressive as it passes to the south. This model shift as pulled back some QPF amounts as the more ample accumulations will be eastward and into Colorado extending to the High Plains, reaching as far as western portions of Nebraska and Kansas. Precipitation lingers into later parts of Wednesday but most activity will end as the upper trough pushes east and lifts out of the state. Wednesday morning will be the coldest of the week, with freeze warnings upgraded for many lower elevations east of the Divide.

Beyond Wednesday, expect upper level ridging to build in from the west with increasing convergence aloft. This will push the main finger of the PFJ to push northeast for the Dakotas and into the Great Lake/Missouri River Basin areas of the country. Models have backed off on this extending a bit southwest for northeastern portions of the CWA for Saturday, looking to remain at best, for far northeastern parts of the state itself. Ridging and northwest flow dominates the weather pattern for the weekend and beyond into next week with dry conditions and a warming trend in store going forward.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 416 PM MDT Tue May 5 2026

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

The area continues to be under the influence of a low over the southwestern CONUS and a broader trough across the northern CONUS. This will lead to scattered rain and snow showers for KBPI, KPNA, and KRKS late this afternoon and evening; MVFR to IFR conditions are possible at these terminals, with KRKS expected to see the most persistent impacts through tonight. KRKS will also see an increased east to northeast wind tonight with gusts to around 30 knots. KJAC is expected to remain VFR and largely miss out on this activity, though surrounding mountains will be frequently obscured. Conditions will improve by sunrise Wednesday as skies clear, with lighter winds and VFR conditions expected through the afternoon.

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

The area continues to be under the influence of a low over the southwestern CONUS and a broader trough across the northern CONUS. This will lead to scattered rain and snow showers for terminals through tonight. The most persistent MVFR to IFR conditions are expected at KLND and KRIW. Conditions are expected to begin to improve after around 08Z, with skies clearing further through the rest of Wednesday morning. This will lead to mostly sunny or scattered skies and VFR conditions through Wednesday 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

Freeze Warning from 1 AM to 9 AM MDT Wednesday for WYZ003>006- 010-011-017-018-020.

Winter Weather Advisory until 1 AM MDT Wednesday for WYZ009- 015.

Winter Weather Advisory until 7 AM MDT Wednesday for WYZ019- 030.