textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- A chance of light precipitation today, then drier and warmer on Sunday.

- A Canadian low will bring mountain showers, large temperature swings, and windy conditions Tuesday through Saturday.

SHORT TERM /Through Monday Night/

Issued 259 AM MST SAT MAR 7 2026 An upper ridge will continue to build east through the weekend. A weak short wave passage coupled with weak warm advection and high precipitable water content brings increased cloud cover and a chance of precipitation today. Several high resolution model runs this morning have lowered chances of precipitation particularly south of the Snake River Plain today. Have maintained 15 percent across the lower Snake Plain west of Mountain Home and southeast Oregon down to the Nevada border this morning; however, amounts will be light if any, with spotty coverage at the lower elevations. A low chance (20-30 percent chance) of showers lingers over the west central Idaho mountains on Sunday, north of McCall to Yellow Pine. Snow levels will start at mountain valley floors this morning where up to an inch of accumulation is possible.

After some morning fog, dry and notably warmer temperatures will set up on Sunday as the ridge moves overhead. Warmer spots will see highs in the lower 60s, with the entire region reaching around 10 degrees above normal. Zonal flow aloft, directed by a Canadian trough, will begin to influence the region by Monday. This will bring increasing gusty winds, cooler temperatures, and mountain precipitation for the start of the week. The primary frontal passage will occur late Monday into Tuesday, with the best chance of precipitation over high terrain in northeast Oregon and southwest Idaho (30 to 50 percent chance). West to northwest winds will strengthen Monday afternoon, especially across the Magic Valley and high desert regions.

LONG TERM /Tuesday through Saturday/

Issued 259 AM MST SAT MAR 7 2026 A pronounced Canadian cold front will become well-established over the region on Tuesday. Strong west-northwest flow aloft, along with a tight pressure gradient from the front, will support gusty west/northwest winds at the surface, especially over south-central Idaho. Tuesday daytime temperatures will be cooled by 10-15 degrees compared to Monday. While the bulk of the moisture will remain north of the forecast area, a chance (40-60%) of light snow is forecast across northeast Oregon and west-central Idaho throughout the day. An upper ridge centered off the southern California coast will start to build northward and allow above normal temperatures to return across the forecast area on Wednesday and especially Thursday. Moisture will continue to stream into the Pacific Northwest during this time, which will maintain precip chances (30-60%) across the northern zones both days. Windy conditions are anticipated in the afternoons, this time affecting more of southeast Oregon and central Idaho as surface flow transitions to south/southwest. Some ensemble members are currently favoring the return of the colder, Canadian airmass sometime late Friday or Saturday, which would extend precipitation chances southward across much of the area. Forecast temperatures are a bit uncertain Fri/Sat due to this possibility, but surface winds will remain gusty.

AVIATION /12Z Saturday through Sunday/

Issued 500 AM MST SAT MAR 7 2026 A 30% chance of MVFR in stratus/light precip at most TAF sites through late morning or early afternoon. Mtn obscuration. Otherwise VFR. Snow levels 4.5-6.5kft MSL, rising from west to east to 6-8kft by late AM. Surface winds: light and variable, then W to NW 5-15 kt this afternoon. Gusts to 20-25 kt around KJER/KTWF. Winds aloft at 10kft MSL: NW to N 20-40 kt.

KBOI...A 30% chance of light rain with MVFR ceilings this morning, then VFR and dry this afternoon. Surface winds: SE around 5 kt, shifting to NW 5-12 kt around Sat/18Z.

Sunday Outlook...Mainly VFR and dry Sunday, except isolated showers over the northern mountains and patchy valley fog/low stratus in the morning. Snow levels 6.5-7.5kft. Surface winds: SW to NW 5-15 kt, with afternoon gusts to 15-25 kt.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.