Area Forecast Discussion

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Partial clearing tonight through Saturday morning.

- Widespread rain and high elevation snow late Saturday into Sunday, with the highest precipitation amounts across southern Idaho. A slight chance of thunderstorms Saturday evening. - Cooler with gusty winds Sunday, and especially Sunday night, then drying and warming Monday through Wednesday. Slight chance of precipitation late week.

SHORT TERM /Through Sunday Night/

Issued 355 PM MDT FRI OCT 30 2026 The first of two pcpn events was exiting Idaho zones to the northeast this afternoon. This will be followed by partial clearing tonight before the next stronger system approaches Saturday. That system will include subtropical moisture, with further enhancement by a developing cold front in OR. Rain will spread northward into our CWA late Saturday, mostly on the Idaho side, and will affect our CWA strongly Saturday night through Sunday morning, with the cold front passing through Sunday morning. SPC still has a slight chance of thunderstorms Saturday afternoon and evening in southwestern Idaho. Latest model QPF has increased slightly from the previous cycle for Saturday afternoon through Sunday, with totals now estimated .40 to 80 inch in Idaho mountains, .15 to .30 inch In Idaho valleys and eastern Oregon mountains, and less than .10 inch in OR valleys. Winds will shift to northwest Sunday and increase Sunday afternoon, and especially Sunday night in the Snake Basin, possibly reaching advisory criteria east of Boise late Sunday night.

LONG TERM /Monday through Friday/

Issued 355 PM MDT FRI OCT 30 2026 Upper-level ridging will build over the western CONUS early next week, returning dry conditions. Through the midweek, a weak upper- level shortwave will move onshore and through the Great Basin, although impacts are expected to be minimal. Greater impacts are expected late week when another system moves into the Pacific Northwest. Precipitation chances currently reflect some disagreement when the system will move in, but precipitation chances of 10-30% are currently forecast. Temperatures will cool slightly at higher elevations while holding nearly steady at lower elevations. Winds will generally be light through the week with patchy fog expected in valleys.

AVIATION /06Z Saturday through Sunday/

Issued 1126 PM MDT FRI OCT 30 2026 Mainly VFR under SCT-BKN mid to high clouds, becoming more OVC Saturday. Patchy valley fog overnight through morning. Isolated showers returning Saturday morning, with coverage increasing in the afternoon/evening. Isolated thunderstorms near south-central ID in the evening. VFR-MVFR in rain showers, IFR-LIFR in mountain snow. Mountains obscured in precipitation. Snow levels 6500-8000 ft MSL. Surface winds: SE-SW 5-10 kt through morning, becoming S-SE 6-11 kt in the afternoon/evening. Winds aloft at 10kft MSL: S-SW 10-25 kt.

KBOI...VFR with BKN-OVC mid-high clouds tonight through Saturday. Isolated to scattered showers Saturday afternoon, becoming widespread Saturday night. Surface winds: variable to SE 4-8 kt.

Sunday Outlook...Precipitation continuing, tapering off from W-E. VFR-MVFR in rain showers, IFR-LIFR in mountain snow. Mountains obscured in precipitation. Snow levels lowering to 5500-6500 ft MSL. Surface winds: W-NW 10-20 kt with gusts 20-30 kt behind a cold front.

BOI WATCHES / WARNINGS / ADVISORIES

ID...None.

OR...None.