Area Forecast Discussion

KEY MESSAGES

- Dry, breezy afternoons and warm through Tuesday.

- Temperatures 10 to 15 degrees above normal through Tuesday. - Showers and thunderstorms, windy, and much cooler Tuesday night through Thursday decreasing Friday, as a cool upper level trough and several following troughs move through.

SHORT TERM /Through Wednesday Night/

An upper ridge will continue warm, dry weather in our CWA through Tuesday morning, with clouds increasing from the south and west from a deep Pacific upper low off California near 40/130. Later Tuesday the low will come inland and bring pcpn to our CWA. Showers will maximize Tuesday night and Wednesday as the low moves right over our area. We have a 20 percent chance of thunderstorms in eastern OR Tuesday afternoon when lapse rates are steepest due to warm air still at the surface, then shifting into western Idaho Tuesday evening and central Idaho Wednesday along and ahead of an eastward-moving cold front. High temps today and Tuesday will be in the 60s-70s in the mountains and lower 80s in the southern valleys, then cool 20-30 degrees behind the front, too cold to support further thunderstorms. The snow level will lower to near 5500 feet Wednesday with several inches accumulation. Post-frontal west winds will increase Wednesday to near advisory speeds in southeast Oregon, and in the Snake Basin south to the Nevada border.

LONG TERM /Thursday through Monday/

Breezy conditions and scattered showers will linger through Thursday while the area remains influenced by a departing upper low. Below- normal temperatures will also continue, with snow levels holding between 4500-6000 ft MSL. On Friday, this upper low will merge with a stalled Canadian trough over the northern U.S., reinforcing cool, northerly flow over the PacNW through the weekend. While instability remains, diminishing moisture will limit shower chances to 10-30% Friday-Sunday. Shower chances will primarily favor the higher terrain of SW Idaho, with 4500-6500 ft snow levels. By Monday, the Canadian trough will eventually shift east as weak ridging builds, resulting in mostly dry, slightly warmer conditions across SE Oregon and SW Idaho.

AVIATION /06Z Monday through Tuesday/

Issued 1126 PM MDT SUN APR 19 2026

VFR. Surface winds: variable 5-15 kt, then SW-SE 5-15 kt with gusts to 20-25 kt in the afternoon. Winds aloft at 10kft MSL: S 10-20 kt.

KBOI...VFR. Surface winds: generally S to SE 5-12 kt.

BOI WATCHES / WARNINGS / ADVISORIES

ID...None.

OR...None.