textproduct: Western and Central Wyoming

KEY MESSAGES

- Light showers will continue across eastern Fremont to Natrona Counties overnight, dissipating by sunrise.

- The main round of shower activity will push into the west from Idaho/northern Utah by early Friday morning, extending to the Divide the remainder of the day (60-80% coverage).

- Strong gusty southwest winds of 40 to 55 mph Friday afternoon and early evening east of the Divide ahead of frontal passage from mid afternoon in the northwest through much of the area by midnight. Winds turn more northwesterly and quickly diminish thereafter.

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

- 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 diminish in wake of the cold front as this system has continued to under perform 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 degree above average due to the suppresional 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 induce 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 /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 1045 PM MDT Thu Oct 22 2026

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

A few terminals remain VFR to start the period but conditions will gradually deteoriate shortly after the start of the period becoming widely MVFR. Showers will move into the area around 09Z Friday with PROB30 groups at KPNA, KBPI, and KJAC. MVFR to possibly IFR conditions may be possible through much of Friday morning. KRKS likely sees showers just miss the terminal but a stray light shower cannot be ruled out between 09Z-12Z Friday. Ceilings at KPNA and KBPI may flirt with MVFR conditions for the remainder of the morning even after showers dissipate. KRKS should see improving ceilings for the rest of the period. Prevailing light rain is expected to move into KJAC by 19Z and persisting near the end of the TAF period. Winds will increase in the morning across all terminals with gusts of 20 to 30 knots at times during the late morning and through much of the afternoon. Winds should decrease a few hours before the end of the TAF period for all terminals. Mountains will be obscured throughout much of the TAF period.

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

Mostly dry with VFR conditions across all terminals through the TAF period with the one exception being KCOD. KCOD may see a few chances for showers during the morning hours Friday and once again by the evening into the end of the period Friday. Winds will be the main focus with widespread strong gusty winds of 30 to 45 knots across KLND, KRIW and KCPR starting around 12Z Friday. Weaker winds of 20 to 35 knots will be possible at the other terminals. Winds gradually decrease by the late evening on Friday before the end of the TAF period. Mountains will be obscured throughout much 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 Saturday sunrise. 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 from noon today to 8 PM MDT this evening for WYZ281.