textproduct: Boise

KEY MESSAGES

- A strong cold front arrives this evening with gusts to 50 mph, increasing showers, and isolated thunderstorms. - Much cooler on Wednesday with widespread precipitation, isolated thunderstorms, gusty winds, and snow levels lowering to 4500 to 5500 feet.

- Precipitation totals of 1 to 2 inch in the mountains, 0.25 to 1.0 inch in the valleys.

- Snow accumulations of 10 to 20 inches on the peaks above 6000 feet especially on the northwest facing peaks.

SHORT TERM /Through Thursday Night/

A strong cold front moves through eastern OR this afternoon and southwest Idaho this evening. Snow levels fall to around 4000-5000 feet behind the front on Wednesday. Showers and thunderstorms form in the late afternoon in eastern OR and sweeps eastward across the area by Tuesday evening. Wind gusts up to 50 mph possible along the cold front this afternoon in eastern OR and this evening in southwest ID. The system moves overhead on Wednesday, precipitation becomes widespread for much of the day, and brings 10 to 20 inches of new snow on the peaks above 6000 feet. Total liquid equivalent precipitation of 1 to 2 inch possible over the mountains with 0.5 to 1.0 inch in the valleys. Precipitation tapers off late on Wednesday afternoon across SE Oregon, and continues over the central ID mountains into Thursday morning. Conditions dry out on Thursday afternoon with cool and breezy conditions.

LONG TERM /Friday through Tuesday/

A shortwave trough will bring another push of precipitation over higher terrain late Friday into Saturday, with temperatures slightly below normal through the weekend. A ridge of high pressure will build over the eastern Pacific, keeping us in cool northwesterly flow through early next week. There is some significant model disagreement in the evolution of another closed low pressure system off the Oregon Coast, which will keep precipitation chances over high terrain near the Nevada border and over the West Central and Boise Mountains in the 20-40% range Sunday through Tuesday. The ridge of high pressure will then move onshore late Tuesday, bringing a slight warming trend through the end of the week.

AVIATION /18Z Tuesday through Wednesday/

Issued 1151 AM MDT TUE APR 21 2026

VFR through mid afternoon. Scattered showers late afternoon, becoming numerous with isolated thunderstorms after Wed/00Z with a strong cold front. Precip continues overnight into Wed with snow levels dropping to 4500-5500 ft MSL and periods of low VFR-IFR in valley rain, and IFR-LIFR in mtn snow. Mtns becoming obscured. Surface winds: SW-SE 5-15 kt with gusts to 25-35 kt near KBNO/KTWF. Winds shift to SW-NW 15-30 kt with 25-45 kt gusts during frontal passage, then weaken behind front. Winds aloft at 10kft MSL: S-SW 15-30 kt, shifting to NW 20-40 kt late tonight.

KBOI...VFR through this afternoon. Showers developing after Tue/23Z ahead of a cold front, with a 20% chance of lightning after Wed/00Z. Cold front passage and wind shift between Wed/02Z-04Z. Rain will become continuous after Wed/09Z, with MVFR conditions during Wed morning hours. Surface winds: S-SE winds 5-15 kt. Shifting to SW-NW 10-20 kt, with a period of 30-40 kt gusts during frontal passage.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.