Key messages
- Widespread precipitation through Friday morning, along with isolated to scattered thunderstorms.
- Thunderstorms through this evening will be capable of producing gusty winds and brief heavy rain, and small hail in Southwest Idaho.
- Windy conditions will develop late tonight and tomorrow behind a cold front, with much cooler conditions Friday and Saturday.
Update
Updated aviation discussion.
Short Term /Through Saturday Night/
Issued 254 PM MDT THU OCT 22 2026 An area of showers and thunderstorms has developed across SW Idaho this afternoon, extending from the OR/ID border into s-central Idaho. The mid-level feature triggering this activity will continue northward through this evening, extending the coverage of showers/storms along its path. The showers/storms will bring gusty winds and moderate rainfall. While the severe wind threat has diminished some, stronger thunderstorms will be capable of wind gusts to 50 mph and brief heavy rain through early evening. Showers continue overnight, with a 10-15% chance of thunderstorms over portions of SW Idaho (mainly the w-central ID mtns). While the wind threat diminishes this evening, brief heavy rain will still be possible from storms overnight and the threat for flooding or debris flows on burns scars remains a risk.
The surface cold front will cross the area later tonight, arriving with gusty northwest winds. Widespread gusts of 30 to 40 mph, will develop across SE Oregon and SW Idaho from the Snake Plain to the NV border. Local gusts of 45 to 55 mph will impact windier locations of Baker and northern Malheur counties through sunrise Friday. The upper low lifts to the northeast on Friday with precipitation tapering off from W-E during the afternoon. Post frontal northwest winds will remain gusty with speeds of 30-40 mph through evening. Snow levels will drop to between 4500-6000 feet over Oregon and between 6-8kft over SW Idaho as precipitations wraps up on Friday. Minor accumulations are possible over higher peaks.
Saturday will see dry and cool conditions with breezy northwest winds. It could start off frosty at lower elevations, though the breezy winds could keep it localized.
Long Term /Sunday Through Thursday/
Issued 254 PM MDT THU OCT 22 2026 A short lived high pressure system will continue to build in over the region Sunday, bringing slightly warmer temperatures and dry conditions through Monday morning. Clear skies overnight paired with the recent precipitation will allow for valley fog to form late Sunday night and again on Monday night, but it should dissipate by the late morning. A cut off low pressure system from the Gulf of Alaska will move in late Monday-early Tuesday, bringing widespread precipitation and cooler temperatures to the region. Disagreement in the timing of the low pressure system exists, with most models pushing precipitation and cooler temperatures late Monday, while a few outlier solutions delay the arrival to Tuesday morning. Current forecast favors high terrain in northeast Oregon and central Idaho for the best chance of precipitation (30-50% chance) through Thursday, with snow levels anticipated to be around 6000-7000 feet. The low will then push to the east, allowing for another ridge of high pressure to build in by Thursday, bringing another slight warming and drying trend for the region.
Aviation /00Z Friday Through Saturday/
Issued 548 PM MDT THU OCT 22 2026 Widespread rain showers and scattered t-storms moving from south to north this evening, with widespread rain showers continuing through Friday afternoon. Gusty outflow winds up to 50 kt, small hail, and heavy rainfall will remain possible in stronger t-storms, mainly in southwest ID. Mountains obscured in rain and lowering ceilings. Surface winds: S-E 5-12 kt with gusts 20-25 kt. Cold front tonight shifting winds out of the W-NW 15-25 kt with gusts 30-40 kt after Fri/06Z. Winds aloft at 10kft: S 15-30 kt.
KBOI...VFR. Widespread rain showers and isolated embedded thunderstorms through the evening. Heavy rain, small hail, and gusty outflow winds near 40 kt possible in stronger storms. Surface winds: SE 8-15 kt with gusts 20-25 kt in the evening, shifting NW 10-15 kt with gusts up to 25 kt following cold front late tonight and after.
Weekend Outlook...Areas of MVFR-IFR in rain/snow mix across SW Idaho through Saturday AM. Snow levels behind the front will drop to 5000-6500 ft MSL, while precipitation tapers off late Friday. Areas of valley fog will form each morning, otherwise VFR. Surface winds: W-NW 10-20 kt with gusts 30-40 kt Friday, then light and variable under 12 kts through Sunday.
Boi Watches/Warnings/Advisories
ID...Flash Flood Watch through Friday morning for IDZ013. OR...None.
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AVIATION.....JY SHORT TERM...DG LONG TERM....SA