textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Temperatures around 5 to 10 degrees above normal through Thursday.

- Slight chance of afternoon thunderstorms Tuesday and Wednesday south along the NV border, but outflow winds may reach southern Malheur, Harney, Owyhee and Twin Falls counties.

- Major change beginning Friday with arrival of a cold front and showers, followed by gusty winds, showers and chance of thunderstorms through Sunday. Snow possible as low as 6500-7000 feet MSL Saturday night and Sunday.

SHORT TERM /Through Thursday Night/

Issued 428 AM MDT TUE JUN 23 2026 An upper level ridge will continue to expand over the region with mid level moisture moving over the area through the short term. Temperatures will remain around 5 to 10 degrees above normal. A pair of disorganized shortwaves will move across the Pacific NW bringing increased clouds, isolated showers and thunderstorms. The first wave moves across the Pacific NW late this afternoon, with increasing high clouds and isolated showers and thunderstorms in eastern OR along the NV border this afternoon. The system will move over Idaho overnight, bringing a chance of sprinkles overnight into Wednesday morning. Isolated showers linger near the NV/ID border on Wednesday morning, generally south of Twin Falls. Similar conditions expected Wednesday with more shower coverage along the NV border and increasing clouds during the afternoon. The main shortwave tracks over the region overnight Wednesday into Thursday morning with light rain showers and a slight chance of thunderstorms. Clouds clear out midday Thursday before increasing clouds late from the next system moving in from the Gulf of Alaska.

LONG TERM /Friday through Tuesday/

Issued 428 AM MDT TUE JUN 23 2026 An upper level trough from the Gulf of Alaska will move southeast into the Pacific NW. A cold front moves through southeast OR and southwest ID on Friday with cooler and unsettled conditions through Saturday and Sunday. Significant precipitation possible with this system if the trough moves overhead. Still significant model differences though in the positioning of this trough, but wetting rains possible Saturday and Sunday with temperatures as much as 10-20 degrees below normal. Light snow possible on the peaks above 7000 feet Sunday morning. Conditions dry out with breezy conditions on Monday and Tuesday as the system moves northeast into Manitoba. This system will keep temperatures below normal under cool northwest flow aloft.

AVIATION /18Z Tuesday through Wednesday/

Issued 1129 AM MDT TUE JUN 23 2026 VFR and patchy smoke over Treasure Valley areas. High density altitude during the afternoon due to heat. Isolated showers/thunderstorms near OR/NV border in the late afternoon through evening, which may produce gusty outflows up to 35 kt over SE OR. Surface winds: variable or E-SE 5-15 kt becoming NW-NE 5-15 kt in the afternoon. Winds aloft at 10kft MSL: W-NW 10-20 kt, then S- SW 5-15 kt in the afternoon.

KBOI...VFR. High density altitude during afternoon from heat. Surface winds: SE 5-10 kt becoming NW 5-15 kt in the afternoon after 20Z.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.