textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Hot and dry.

- Isolated storms in the Magic Valley today and tomorrow.

- Smoke will limit high temperatures and continue degraded air quality.

- A dry cold front this weekend will bring critical fire weather with gusty winds and very dry conditions.

SHORT TERM /Through Thursday Night/

Issued 206 PM MDT TUE JUL 28 2026 High pressure over the four corners will maintain warm and dry southwesterly flow aloft. This will lead to a general warming and drying trend heading into the weekend. Though, embedded shortwaves and lingering smoke will complicate the forecast some. Shortwaves in the flow from a stalled low off the British Columbia coast will trigger afternoon isolated convection near the Magic Valley today and tomorrow. Thunderstorms in this region will be capable of producing outflow gusts up to 45 mph and lightning. Most of the storm activity will be in the eastern Magic Valley and south in the highlands, but traveling gusts and distant lightning still pose a threat to the western valley. The shortwave position will change Thursday evening and central to eastern Oregon will be most favored, especially over higher terrain and mountains. Coverage on Thursday will be very limited, with only a 5% chance of precipitation in this area. Wildfire smoke will be in the area through the forecast period. While it will help cool temperatures by a few degrees each day, degraded air quality will remain.

LONG TERM /Friday through Tuesday/

Issued 206 PM MDT TUE JUL 28 2026 While the four corners high begins to slip out of position Friday and Saturday, warming and drying will continue. Both days will be the hottest in the forecast, with temperatures in lower elevations in the mid to upper 90s. Guidance indicates temperatures around 100 degrees are possible if the smoke clears some, although with southwest flow continuing this is unlikely. The stalled British Columbia low begins to move inland Friday, and is set to bring a dry cold front through the area Saturday evening. With Saturday being the hottest day, this combination of heat, very dry conditions, and frontal gusty winds will lead to critical fire weather across the area. Behind the cold front, Sunday will be 5-10 degrees cooler than Saturday, but dry and gusty conditions will remain, leading to continued elevated fire weather. Temperatures begin to climb again Monday and Tuesday as high pressure rebuilds over Nevada. Southwest flow resumes the transport of hot and dry air early next week.

AVIATION /06Z Wednesday through Thursday/

Issued 1155 PM MDT TUE JUL 28 2026 Widespread wildfire smoke reducing visibilities with MVFR to IFR. Isolated thunderstorms SE of KTWF and KJER Wednesday afternoon with gusty winds up to 45kt in vicinity of storms. Surface winds: mostly variable under 10 kt tonight through morning, except valley winds NW 10-15 kt with gusts to 25 kt near KONO through the morning. Winds aloft at 10kft MSL: SW 5-15kt.

KBOI...MVFR conditions from wildfire smoke overnight through morning. Possible improvements in the afternoon. Surface winds SE 4-7kt overnight through morning.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Air Quality Alert until 2 PM MDT Friday for IDZ011>015-028-029- 033. Air Quality Alert until 1 PM MDT Wednesday for IDZ016-030. OR...Air Quality Alert until 1 PM MDT /noon PDT/ Wednesday for ORZ061>064.