textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- A significant pattern change begins today as a cool upper level trough pushes a cold front through, bringing widespread showers, scattered thunderstorms and cooler temperatures.

- Scattered thunderstorms this afternoon into early Saturday could produce strong outflow winds, small hail and brief heavy rain.

- Temperatures around 15 to 20 degrees below normal Saturday and Sunday.

- Significant precipitation and light snow above 7000 feet possible Saturday through Sunday.

SHORT TERM /Through Sunday Night/

Issued 253 AM MDT FRI JUN 26 2026 A major pattern change is knocking on the door this morning as an area of low pressure dives southward into the Pacific Northwest. The low looks impressive on satellite, and precipitation is filling in across the region. The cold front associated with the low is expected to work through eastern Oregon and southwest Idaho this morning, and will serve as an initial focus of precipitation. As the cold core of the low moves overhead this afternoon scattered to numerous showers and thunderstorms are expected to develop. Model derived soundings show a prolonged period of unstable conditions beginning mid afternoon and lingering into the overnight hours. Enough instability is forecast to support strong gusty winds and small hail with the strongest storms. Guidance suggests a 30-40% chance of gusts greater than 30-35 mph. Anyone with outdoor plans this evening will need to monitor storm activity closely. The combination of abundant lightning and gusty winds will lead to a period of critical fire weather conditions this afternoon and evening.

The low is forecast to settle over Idaho this weekend with significantly cooler temperatures expected. High temperatures are only expected to reach the mid to lower 60s in the warmest spots, and snow levels will drop to 6500-7000 feet by Sunday afternoon. Current projections place the best chances for precipitation this weekend over central and eastern Idaho.

LONG TERM /Monday through Friday/

Issued 253 AM MDT FRI JUN 26 2026 Very good agreement amongst ensemble members that a broad-scale trough of low pressure will dominate the pattern across the west next week. This will keep temperatures below normal, with only a slow warming trend expected throughout the week. Temperatures will approach normal by Thursday/Friday. At this point the week looks to be on the drier side, with our next best shot of precipitation possible late in the week. With the trough in place, it stands to reason that isolated terrain driven showers/thunderstorms will be a possibility each afternoon.

AVIATION /18Z Friday through Saturday/

Issued 1144 AM MDT FRI JUN 26 2026 VFR. Widespread rain showers. Areas of mountain obscuration and local MVFR ceilings. From 26/21Z until 27/04Z scattered thunderstorms with gusts to 35 kt and local heavy rain. After 27/04Z widespread light rain, mountains generally obscured, and areas of MVFR ceilings. Surface winds: Until 27/04Z NW 10-20kt with gusts to 30 kt, then decreasing to 5-10 kt. Winds aloft at 10kft MSL: W 20kt.

KBOI...VFR. Rain showers. Chance of thunderstorms 26/21Z to 27/04Z. Thunderstorm outflow winds up to 35 kt. Otherwise, NW wind 10-15kt until 27/04Z, then NW 5-10kt.

Weekend Outlook...Showers and thunderstorms Saturday and Sunday. Mountains frequently obscured. Local MVFR/IFR over mountains in heavy rain/snow. Snow level lowering to 6500-7500ft MSL Sunday morning. Gusty west-northwest surface winds during the afternoons.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Red Flag Warning until 6 AM MDT Saturday for IDZ400-420-423- 424-426. OR...Red Flag Warning until 6 AM MDT /5 AM PDT/ Saturday for ORZ670>674.