textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Dry, warm and breezy through Tuesday afternoon. - Showers and thunderstorms, windy, and much cooler Wednesday and Thursday as a cool upper level trough moves through.

- Snow levels lower to 4500 to 5500 feet Wednesday and Thursday.

- Precipitation of up to an 1 to 1.25 inch in the mountains, 0.5 to 1.0 in the valleys.

SHORT TERM /Through Wednesday Night/

Issued 250 PM MDT MON APR 20 2026 Dry and mild today with increasing winds as a strong cold front approaches the area. One more warm day expected on Tuesday ahead of the front. A strong cold front moves through late Tuesday night and snow levels fall to around 4000-5000 feet behind the front. Showers and thunderstorms form in the late afternoon in eastern OR and sweeps eastward across the area by Tuesday evening. Wind gusts up to 45 mph possible along the cold front. The system moves overhead on Wednesday, precipitation becomes widespread for much of the morning, and brings 6 to 10 inches of new snow on the peaks above 6000 feet. Total liquid equivalent precipitation of 1 to 1.25 inch possible over the mountains with 0.5 to 1.0 inch in the valleys. Precipitation becomes showery in nature on Wednesday afternoon, and continues over the central ID mountains into Thursday morning.

LONG TERM /Thursday through Monday/

Issued 250 PM MDT MON APR 20 2026 As the upper-level trough moves further east Thursday, the area will be plunged into cool northerly flow through the weekend. Troughing will be in place over much of the northern and northwest U.S. as a Canadian trough becomes stationary through Monday. Breezy conditions and scattered showers will linger through Thursday, thereon having precipitation primarily limited to higher elevations at 10-30% Friday-Sunday. Below-normal temperatures will continue, with snow levels holding between 4500-6000 ft MSL. By Monday, the Canadian trough will eventually shift east, however model solutions are still split on the overall synoptic pattern.

AVIATION /00Z Tuesday through Wednesday/

Issued 524 PM MDT MON APR 20 2026 VFR under mostly clear skies through midday Tuesday. Showers and thunderstorms develop late Tuesday afternoon, increasing in coverage through the evening. Widespread precipitation will continue overnight into Wednesday with snow levels dropping to 4-5kft MSL by Wednesday morning. Low-VFR/MVFR ceilings in valleys and snow/IFR in mtns obscuring terrain on Wednesday. Surface winds: SW-SE 5-15 kt. Gusts to 25 kt through early evening, ramping up 20-30 kt after 18Z Wed. Winds aloft at 10kft MSL: S-SW 10-30 kt.

KBOI...VFR. Light surface winds through ~18Z Tuesday. Gusty crosswinds possible Tuesday afternoon with cumulus development and increasing chance of showers after Tue/22Z. A 20% chance of thunderstorms after Wed/00Z with gusty outflow winds possible.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.