textproduct: Boise

KEY MESSAGES

- Cool and dry this weekend, frost and freeze possible Saturday and Sunday mornings in lower valleys.

- Seasonable temperatures with an unsettled pattern bringing a chance of rain and high mountain snow early next week.

SHORT TERM /Through Sunday Night/

Drier conditions will set up over the weekend under a west- southwest flow. Clearing skies and lighter winds tonight will support near freezing temperatures in lower Snake Plain Saturday morning. Sheltered locations are more likely to see frost with cold spots touching freezing. This will be the case again on Sunday morning as well, though a moderating air mass and the introduction of high clouds could limit coverage. Saturday is cool and breezy, but not as windy as today. Southwest flow sets up on Sunday as a low pressure system approaches the Pac NW coast. This shift will bring warmer temperatures and increase easterly winds across open terrain. Moisture in the southwest flow aloft will increase high cloud cover, starting across SE Oregon late Saturday. Temperatures are near normal Saturday (~60 in valleys and ~50 in mtn valleys) warming to around 5 degrees above normal on Sunday.

LONG TERM /Monday through Friday/

A compact shortwave upper trough will approach the Pacific NW on Monday and bring a return closer to normal temperatures, along with another round of precipitation to the region Monday evening into Tuesday. There are still some timing differences amongst deterministic model guidance - most notably the ECMWF which is faster and depicts a secondary upstream system off the BC coast - but probabilistic guidance favors Tuesday as the more active day, especially into west-central and central Idaho. QPF amounts are generally expected to remain near or below 0.25 inch even in the mountains, given the lack of a significant moisture tap. Snow levels will remain above 6000 feet throughout this event as well, which will limit snow accumulations primarily to higher elevation mountainous areas. Temperatures will modulate during the week and remain slightly above seasonal normals. In the wake of the early week system, the pattern will remain unsettled, with low-end (up to 20%) probabilities maintained each day, especially in the mountains. The next significant storm system takes shape Thursday and Friday. Moisture will remain quite limited and remain confined to the Desert Southwest, with precipitation chances beginning to increase again on Friday.

AVIATION /18Z Friday through Saturday/

Issued 1137 AM MDT FRI OCT 23 2026 Occasional low VFR to IFR in rain/low clouds and IFR-LIFR in mtn snow persists across southwest Idaho through this afternoon. Mountains obscured in Idaho. Clearing from west to east with precip tapering off through this evening. Snow levels 5k-6kft. Light winds and mostly clear skies by Saturday morning. Surface winds: W-NW 15-25 kt with gusts 25-45 kt behind cold through Fri afternoon. Becoming light and variable overnight. Winds aloft at 10kft MSL: N 15-30 kt, becoming variable 5-10 kt Saturday morning.

KBOI...Rain showers tapering off by 23/20Z afternoon. Brief MVFR may persist this afternoon due to low ceilings, but mainly VFR. Surface winds: 10-20 kt with gusts 20-30 kt, becoming light and variable overnight.

Weekend Outlook...Mainly VFR with dry conditions through Sunday, except patchy morning fog/low stratus Sat and Sun mornings. Surface winds: variable 5-12 kt Sat/Sun.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.