textproduct: Boise

KEY MESSAGES

- Isolated afternoon showers and thunderstorms on Thursday, primarily over the higher terrain of southwest Idaho and along the Nevada border.

- Gradual warming through Saturday.

- 20% chance of afternoon thunderstorms early next week.

SHORT TERM /Through Friday Night/

The region remains under a broad and relatively dry cyclonic flow tonight as an upper level trough continues to shift eastward into the Rockies. There remains enough moisture and instability for isolated showers and thunderstorms this evening. Skies will remain mostly clear overnight, though some lingering moisture in the north may support a few clouds. Low temperatures will be around seasonal normals.

On Thursday, a weak shortwave is progged to rotate through the backside of the departing trough. While overall moisture is limited, cold air aloft combined with daytime heating will create enough instability for isolated showers and a few thunderstorms. The best chances for this activity (15 to 20 percent) will be focused over the central Idaho mountains and higher terrain near the Nevada border during the afternoon and evening hours. Any storms that form will be capable of producing small hail and brief gusty winds. Elsewhere, expect mostly sunny conditions with light winds.

By Friday, an upper level ridge will begin to amplify over the Great Basin, leading to a more stable and warmer pattern. High temperatures on Friday will climb into the mid 70s for the lower elevations, which is roughly 5 to 8 degrees above late April averages. Winds will generally remain light and follow diurnal patterns. Mostly clear skies will persist through Friday night as the ridge axis moves directly overhead.

LONG TERM /Saturday through Wednesday/

A trend towards warmer conditions will continue into this weekend, with highs expected to range between 8 to 12 degrees above normal. This translates to high temperatures in the upper 70s to near 80 degrees for many lower elevation locations, including the Treasure Valley and western Magic Valley. Saturday and Sunday will remain dry across the area with ridging aloft. However, an upper level closed low will develop off the California coast on Sunday and then track eastward through Nevada on Monday and Tuesday. The latest forecast models have trended further south with the closed low and indicate that an upper level ridge will build north of the closed low. The upper low will still be close enough for a chance of showers and thunderstorms across the area on Monday and Tuesday. Chance of thunderstorms will be 10 to 20 percent across the northern half of the forecast area with a 20 to 50 percent chance across the southern half. Model ensembles indicate that the upper level low will move east away from the area and that the upper level ridge over the pacific northwest will become more dominate by Wednesday likely bringing dry and warm conditions to the area.

AVIATION /18Z Wednesday through Thursday/

Issued 1143 AM MDT WED APR 29 2026 VFR. Isolated showers and thunderstorms this afternoon in central Idaho mountains with a 30 percent chance showers approaching KMYL. Skies clearing tonight with light and variable winds less than 10 kts. Winds aloft at 10kft MSL: NW around 15 kts.

KBOI...VFR. Scattered mid-level clouds this afternoon, becoming clear tonight. Surface winds NW 5 to 10 kts this afternoon, becoming light SE at less than 5 kts tonight.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.