Key messages
- Flash Flood Watch for Local Burn Scars: A Flash Flood Watch is in effect for the Wapiti, Ohio, and Big Rock burn scars from late tonight through Friday, where incoming precipitation could trigger debris flows and rapid runoff.
- Widespread showers and storms this evening through most of the day Friday.
- Much colder Friday. Daytime temperatures will drop by around 20 degrees.
Discussion
Issued at 139 PM MDT Thu Oct 22 2026
The low pressure system over California will continue to move inland and lift northward today, then overhead on Friday before exiting the region on Saturday. Showers and thunderstorms will overspread the CWA late this afternoon and tonight into Friday morning. Precipitation will trend lighter moving into Friday evening and conclude for the entirety of the forecast area by early Saturday morning.
The 48-hour National Blend mean QPF has increased slightly, sitting at roughly an inch across much of the forecast area, with closer to 1.25 to 1.50 inches across the central mountains eastward into the Island Park region. The 10th percentile is around 0.25" to 0.50" for much of eastern Idaho and closer to 0.75" for the central mountains into the Island Park region. The 90th percentile has increased to 1.50 to 2 inches for most of east Idaho, with around 2 inches for the central mountains. The official WPC forecast continues to run on the dry end, still sitting between the 10th and 25th percentile with much of the area forecast to receive less than 0.75" with 1 inch to 1.25 inches across the high elevations of the central mountains and Montana Divide region. Thus, a large spread continues to reflect a broad range of model solutions.
The snowfall forecast remains consistent with most of the snow falling above 7000 feet and mainly across the central mountains. There will be a 20 degree or so drop in temps between Thursday and Friday and temperatures Saturday morning will start off below freezing for many, but precipitation will largely be concluded by that time.
Dry weather is likely over the weekend into early next week. Temperatures will be a touch below average over the weekend and return to seasonable levels for next week.
Aviation /00Z Tafs Through 00Z Saturday/
Issued at 533 PM MDT Thu Oct 22 2026
Widespread showers expected to increase through the evening period. A line of thunderstorms moving through the central Idaho mountains will push to the north through 04z. Another line of thunderstorms coming from Nevada and Utah will sweep into KBYI KPIH KIDA through 05Z By the time it reaches KDIJ it should be rain showers. Upper level low will move through the area during the next 24 hours producing widespread MVFR conditions due to ceilings and visibiilty with rain showers. Anticipate some IFR conditions with heavier rain showers. Winds will increase by 18z tomorrow in the Snake River airport sights.
Fire Weather
Issued at 102 AM MDT Thu Oct 22 2026
Isolated to scattered thunderstorms are expected today. Some gusts to 35 mph are possible near storms. Otherwise winds should remain light. The wetting rains should arrive tonight and continue into Friday.
Pih Watches/Warnings/Advisories
None.
DISCUSSION...Cropp/13 AVIATION...Preston FIRE WEATHER...13