textproduct: Western and Central Wyoming

KEY MESSAGES

- Above average temperatures continue Wednesday and Thursday ahead of the next storm system.

- Increasing winds Thursday, strongest east of the Divide and across the wind corridor ranging from 40 to 55 mph gusts likely (80-90% confidence).

- Increasing rain chances Thursday morning and throughout the day with mountain snow likely for western mountains later in the afternoon and overnight into Friday, spreading to eastern mountains Friday evening.

- A cold front pushes through Friday morning, bringing cooler temperatures to near seasonable heading into the weekend as well, reinforcing snow chances lowering to 8-9kft to impact mountain passes for Friday evening and Saturday morning.

DISCUSSION

Issued at 130 AM MDT Wed Oct 21 2026

IR currently depicts mid level clouds pushing in across western and northern parts of the CWA from the southwest, extending from Baja Californian moisture extending through the Four Corner Region. WV imagery shows the main finger of the PFJ extending across southern Canada and a strong upper level low off the central Californian coastline. This low will begin its eastern extent Wednesday night into Thursday as it becomes a more open and progressive wave that will strengthen the southwest and divergent flow into the CWA out of northern Utah. This is where the stronger PVA anomalies will occur extending moisture content into southern portions of the state by Thursday morning.

The aforementioned PFJ will start to dip across the Pacific northwest aligned with the main low as it becomes more open late Thursday with an increasing jet max pushing 120-130kts. This deepens the northern portions of this system with increased divergence aloft. This increases the pressure gradient across much of the CWA about 5 to 7 mb across the state, strongest across the south. Southwest winds push 40 to 55 mph Thursday afternoon during peak heating and mixing to the surface, strongest across the wind corridor from Sweetwater through eastern Fremont to Natrona Counties. Occasional gusts over 60 to 65 mph possible (40-50%) for the higher terrain areas of South Pass and outer drive of Casper Mountain. There is low confidence on high wind criteria being met for this period of time, but winds remain elevated overnight into Friday morning with wind shifts occur due to a passing cold front extending through the CWA into the afternoon hours Friday.

Precipitation wise, expect shower activity to increase out of northern Utah into southern portions of the CWA Thursday morning pushing north throughout the day. Much of the QPF will fall west of the Divide with some higher terrain mountain snow expected by late Thursday afternoon and especially overnight as temperatures fall. This will be reinforced with FROPA on Friday, lowering freezing levels to 8-9kft as the system shifts east of the Divide, and thus, impacting the Bighorns with mountain snow. Mountain passes, to include Teton, Togwotee, and South, extending to Granite/Powder River, will see the impacts and hazards late Friday and into Saturday morning as the trough shifts northeast by day's end Saturday. Probabilities for snowfall totals look to be of higher confidence across western mountains, to include the Winds, of 6 inches or more around 60-70%. The Bighorns are of lower confidence around 30-40% for later Friday and into the overnight hours. With snowfall totals of not great confidence, and being Friday for impacts, it has been decided to include surrounding offices to not issue any headlines at this time. Model guidance has been up and down the past couple of days with this round bumping totals up once again and will need higher confidence to do so moving forward.

Beyond that, expect more seasonable to just below average temperatures post FROPA Friday and into the weekend to fell more Fall-like for this time of year moving towards the later half of October. Another low extending out of the Gulf of Alaska looks to push down along the L/W pattern into the Pacific northwest late Sunday that will near the CWA early next week. This will not only reinforce this cooler air but continue the active pattern that has a better track for stronger snow totals. Too soon to judge the impacts at this point in time, but this looks to have a better track for higher mountain snow along and west of the Divide. Stay tuned for forecast updates and any headline issuance later Wednesday or Wednesday night as confidence grows for impacts on Friday into Saturday.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 445 AM MDT Wed Oct 21 2026

VFR conditions for the entirety of the period at all TAF sites. Mid level ceilings west of the Divide to few and scattered to the east. Showers in the vicinity of JAC this morning coming out of eastern Idaho and over the Tetons, much of which will remain west of on station, carrying only VCSH at this time. Otherwise, relatively light winds at most locations 10kts or less outside of KRS that will see gusts up to 25kts between 20-01Z during peak heating of the afternoon. Winds become light there after towards sunset and overnight with radiational cooling through Thursday morning. Expect stronger winds Thursday ahead of the next system and cold front for Friday.

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

RIW WATCHES/WARNINGS/ADVISORIES

None.