textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Light mountain snow showers and gusty winds through Friday.

- Patchy frost overnight and Friday morning, then widespread frost and areas of freezing temperatures Saturday morning.

- Remaining unsettled through the weekend and into next week. Temperatures will gradually warm toward normal.

SHORT TERM /Through Saturday Night/

Issued 226 PM MDT THU APR 23 2026 The region will remain on the back side of a broad upper trough over the northern Great Plains into the weekend. Shortwave energy dropping out of Canada will keep a 20-30% chance of snow showers over the w-central Idaho mtns on Friday. Snow levels will be down to mtn valley floors, but showers will be light and any snow accumulation will total less than an inch. Otherwise, dry and breezy conditions across SE Oregon and SW Idaho. Winds will ramp up in the afternoon with gusts peaking around 30 mph across the Snake Plain south and east of Boise. A closed low off the CA coast will draw the trough farther south and west on Saturday. Cooler air aloft will increase instability over higher terrain along the NV border, supporting a 20-30% chance of afternoon showers. The environment will be borderline for thunderstorm development, topping out around 10%. Lower elevations stay dry on Saturday, seeing slightly warmer temperatures and lighter winds.

Lower valleys will see patchy frost tonight, then widespread frost and areas of freezing temperatures late Friday night. For tonight the wind, clouds and borderline temperatures should limit frost formation and as such have held off on a product, covering the threat with patchy frost wording in forecast. Friday night will see widespread frost and areas of freezing temperatures with lows 29-34 from Ontario to Twin Falls/Jerome.

LONG TERM /Sunday through Thursday/

Issued 226 PM MDT THU APR 23 2026 A trough extending from a low centered over Canada will dig into the region Sunday into Monday, bringing cool, below normal temperatures and high terrain precipitation (30-50% chance). Showers will generally be light, with minimal snow accumulation anticipated. Snow levels will begin around 4500-5500 feet MSL on Sunday, rising to 5500-6500 feet on Monday. High pressure will then move into the region, bringing a warming trend through the end of next week. Lingering mountain showers are possible through Thursday with this warming trend, but forecast confidence is low (20-30% chance).

AVIATION /06Z Friday through Saturday/

Issued 1150 PM MDT THU APR 23 2026

Generally VFR. Scattered showers mainly over the w-cntrl mtns early Fri/AM, then again Fri/PM. Patchy fog/low stratus early Fri/AM in sheltered mtn valleys. IFR/LIFR conditions in snow showers and fog/low stratus. Snow levels: 2.5-4.5 kft MSL Fri/AM. Then 3.5-6kft MSL Fri/PM, lowest over the w-cntrl mtns. Surface winds: W-N 5-15 kt overnight. Winds aloft at 10kft MSL: W-NW 15-30 kt.

KBOI...VFR. Surface winds: NW under 10 kt overnight, then NW 10-15 kt with gusts up to 25 kt Fri/PM.

Weekend Outlook...Generally VFR. Unstable conditions will support a chance of IFR snow/mixed showers over the higher terrain Sat/Sun afternoons. Occasional valley rain showers also possible. Slight chance of thunderstorms near NV border Sat/Sun. Snow levels: lowest Friday at 3-4kft MSL, rising to 4-6kft MSL for Sat/Sun. Mtns obscured in showers. Surface winds: NW-N 10-20 kt with 20-30 kt gusts Friday, then W-NW 5-15 kt with 15-25 kt gusts Sat/Sun.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Freeze Watch from late Friday night through Saturday morning for IDZ012-014-016. OR...Freeze Watch from late Friday night through Saturday morning for ORZ064.