textproduct: Western and Central Wyoming

KEY MESSAGES

- Valley rain and mountain snow is forecast across western and northwestern Wyoming through 9 PM, at least, before shifting into northern and central Wyoming after sunset.

- Gusty southwest winds of 40 to 55 mph are expected through the early evening from Sweetwater to Fremont, Natrona, and Johnson Counties. A cold front will shift winds to be northerly and breezy this evening.

- Low relative humidity values around 20 percent, gusty winds, and a wind shift will result in near-critical fire weather conditions across Johnson County this afternoon.

- Much cooler temperatures are forecast this weekend behind this weather system with near seasonable to below average for this time of year.

DISCUSSION

Issued at 130 AM MDT Fri Oct 23 2026

IR shows cooling cloud tops across the CWA as the tropical moisture has begun to interact with the open wave pushing up from the southwest nearing the CWA. WV imagery shows a disjointed PFJ dipping around the trough to the west but mainly to the north into southern Canada with a 120-130kt jet max helping to aid the aforementioned system that will affect the CWA throughout Friday and lingering into Saturday. Radar shows a few scattered light showers pushing across Natrona County that will diminish before sunrise Friday morning. The main push of precipitation will come from eastern Idaho and northern Utah later through the overnight hours that will eventually spread east to the Divide later in the morning. Some rumbles of thunder are possible with instability values in the 100-200 J/kg range into the afternoon. PVA anomalies look to be more constrained over Idaho and into southern Montana, limiting any significant accumulations but limited mountain snow is likely for the higher elevations of the western mountains. More prominent for the Tetons and into Yellowstone, 3 to 5 inches are possible but with lower confidence at this time (30-40%). Freezing levels will remain above 10kft ahead of the cold front later in the afternoon with limited precipitation at that time of FROPA.

Winds will be of concern today remaining elevated in many areas into Friday morning already, with a possible weak mountain wave off the southern Winds into the eastern parts of the Wind River Basin. Gusts up to 30 to 35 mph are possible with this but not of high concern at this time. Winds will increase through the late Friday morning hours as the gradient continues to tighten ahead of FROPA. Southwest gusts up to 40 to 55 mph are likely for much of the area, strongest east of the Divide. HiRes models indicate the front to push into Yellowstone by around 4PM and pushing southeast through the evening hours, reaching east of the Bighorns by 6-7PM where the highest of fire weather concerns will be. Moisture will be limited east of the Divide, but areas around the Cody Foothills off the Absarokas will have the best chance for precipitation with frontal passage, outside of the upslope flow of the Bighorns to Owl Creeks/Bridgers. Minimal high elevation snow and limited in the valley rain of significance but around a 20 percent coverage on this occurrence heading towards sunset Friday evening. By sunrise Saturday morning, any shower activity will have diminished in the wake of the cold front as this system has continued to underperform with the models with its weaker trajectory over time this past week. Being indicative of the winter to come in the stronger El Nino pattern, it could be a recurring theme going forward and especially east of the Divide.

Beyond that, temperatures Friday afternoon will push 10 to 20 degrees above average due to the suppressional heating ahead of the aforementioned cold front. Behind it, expect more seasonable to just below average temperatures over the weekend into early next week to feel more Fall-like heading into the last week of October in Wyoming. Behind this quick pushing system into the northern Great Plains, expect induced ridging for the later half of the weekend ahead of the next bowling ball of a low coming from the Gulf of Alaska. By Monday morning, expect it to reach the Pacific Northwest remaining a closed low that will begin to affect the CWA and in particular for the west by Tuesday. This will be more inclined for western mountain snow and reinforcing the cooler air to allow for even some valley snow west of the Divide. Time will tell, but models show a disjointed system with much disagreement still to come. Stay tuned for updated forecasts beyond this system for Friday in the coming days.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1115 AM MDT Fri Oct 23 2026

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

Low-end VFR conditions/mountain obscurations continue over the area with VCSH streaming northward. Most of the showers are expected to stay to the west over ID through the rest of the afternoon before pushing in over western WY by 00Z. MVFR conditions will become more widespread through the evening, impacting KJAC but staying north of KBPI/KPNA. Rain will quickly end by 06Z, with clouds scattering out through 12Z. MVFR ceilings will develop at KBPI/KPNA and the Green River Basin by 14Z and last through 18Z.

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

Winds will continue to be the main focus this afternoon with widespread strong gusty winds of 30 to 45kt across Natrona County and KCPR. Weaker winds of 20 to 35kt will be possible at the other terminals. Winds will quickly decrease by 00Z/01Z. A cold front will reach KCOD by 02Z, turning winds northerly and bringing a chance for rain showers through 06Z. The front will proceed southward, reaching the remaining terminals between 04Z and 08Z. No precipitation is expected to occur with the frontal passage at the other terminals. Wind gusts of 20 to 25 kt will occur at all sites, except KLND. MVFR ceilings will coincide with the front, with these conditions lasting at KCPR, KRIW/KLND through the end of the TAF period.

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

FIRE WEATHER

Issued at 130 AM MDT Fri Oct 23 2026

Near critical fire weather conditions expected this afternoon and early evening through sunset. Gusty southwest winds up to 40 to 55 mph widespread east of the Divide. Humidity values will drop to 20 to 25 percent with the unseasonable temperatures in the afternoon, lowest across Johnson County where a Red Flag Warning is in effect from noon through 8PM this evening. A cold front will push through from northwest to southeast from mid afternoon through sunset turning winds out of the northwest but diminish thereafter becoming 10 to 20 mph by midnight, lingering in eastern counties through sunrise Saturday. Shower activity west of the Divide will diminish the fire weather concern somewhat, but still elevated due to the strong winds.

RIW WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 8 PM MDT this evening for WYZ281.