textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Isolated afternoon thunderstorms today and tomorrow with small hail, gusty outflow winds, and brief heavy rain.

- Slightly below normal temperatures with valley rain showers and mountain snow showers Sunday and Monday.

- Much cooler temperatures with periods of precipitation Wednesday through Friday.

SHORT TERM /Through Monday Night/

Issued 311 AM MDT SAT APR 11 2026 A few showers linger around the region this early morning, while thunderstorm activity has moved to the north. The showers and thunderstorms observed Friday evening brought gusty winds up to 50 mph and rainfall totals of nearly half an inch to the Owyhee Mountains. The Boise airport measured 0.39 inches of rain in since 7 pm MDT. The coastal low that has kept us in warm, unstable southerly flow will continue to circulate off the northern California coast today. A weak shortwave trough will move northward today, bringing another push of showers and slightly cooler air over the region. Instability is less favorable over the area as a whole compared to yesterday, but south central Idaho and the Oregon-Nevada border will see a slight chance of thunderstorms this afternoon and evening. Hazards will include gusty outflow winds, small hail, and another push of heavy rain.

The low will finally move onshore Sunday morning, bringing much cooler air and widespread precipitation to the region. Temperatures will drop about 5-10 degrees with this cooler air on Sunday, and snow levels will drop further as precipitation tapers off late Monday. The threat of afternoon thunderstorms remains on Sunday, especially in south central Idaho, but confidence is low. Snow levels will generally be around 6000-7000 feet on Sunday, dropping to 5000-6000 feet by Sunday night into Monday morning. High peaks will see accumulations of 6-12 inches of snow, while mountain passes along US95 and ID21 will see anywhere from 3-6 inches of snow by Monday morning. Most locations will see 0.50-1.0 inches of rain by Monday morning, with areas southeast of Mountain Home only seeing 0.20-0.30 inches of rain.

LONG TERM /Tuesday through Saturday/

Issued 311 AM MDT SAT APR 11 2026 An impressive Gulf of Alaska low will dive down the British Columbia coast on Tuesday, with generally westerly flow aloft as the remnants of the last system move southeast. A few showers will linger over high terrain on Tuesday, but conditions will generally be dry and mild. This low will then move into the Pacific Northwest on Wednesday, bringing much cooler temperatures, breezy winds, and widespread precipitation. Temperatures will be about 10 degrees below normal on Thursday into Friday, with light snow down to 3000-4000 feet by Thursday morning. Model agreement remains high with this storm track, but slight variations in the position of the low will lead to fluctuations in the temperature and precipitation forecast. As this trough digs to our east, the region will be under dry northwesterly flow on Friday. A ridge of high pressure will then build in on Saturday, bringing a return to normal or slightly above normal temperatures and dry conditions just in time for the weekend.

AVIATION /12Z Saturday through Sunday/

Issued 535 AM MDT SAT APR 11 2026

Generally VFR. Scattered showers and isolated thunderstorms today with outflow winds up to 35 kt and brief MVFR-IFR in heavy rain. Mountains obscured in low clouds and precip. Snow levels lowering to 6500-7500 ft MSL this afternoon, then to 5500-6500 ft MSL Sun/AM. Surface winds outside of storms: SW-NW 5-15 kt with PM gusts to 20 kt. Winds aloft at 10 kft MSL: S-SW 15-30 kt.

KBOI...Generally VFR. Periodic rain showers today with a slight chance (20%) of thunderstorms this evening. Surface winds outside of showers: E-SE 5-8 kt.

Sunday Outlook...Thunderstorm coverage will be more limited on Sunday, but numerous rain/mtn snow showers with gusty winds are expected. MVFR-IFR conditions in heavier precip. Mountain obscuration. Snow levels lowering to 5000-6000 ft MSL. Surface winds outside of storms: S-W 5-15 kt with PM gusts to 15-25 kt.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.