textproduct: Boise

KEY MESSAGES

- Isolated thunderstorms south of Twin Falls this afternoon, then hot and dry Saturday.

- Slight chance of thunderstorms over central ID mountains and south-central OR Sunday afternoon, with chances expanding area-wide Monday. - Steady warming trend, with the hottest temperatures expected Saturday through Wednesday.

SHORT TERM /Through Sunday Night/

Near-zonal flow is expected today as a weak trough passes to the north. Residual mid-level moisture and instability will allow weak, isolated showers/thunderstorms to develop in south- central Idaho near the NV/UT borders this afternoon, with outflows to 25-35 mph. Thereafter, dry and hot conditions will set up across the region for the 4th of July, as an upper level ridge centered over the southern U.S. builds west and north into ID/OR. The placement of this ridge will allow marginal subtropical moisture to funnel into the region on Sunday, supporting a slight chance of elevated thunderstorms for the central Idaho mountains and south-central Oregon in the afternoon. Sunday temperatures will increase further from Saturday, peaking in the mid/upper 90s across lower elevations.

LONG TERM /Monday through Friday/

A large upper-level trough will approach the Pacific Northwest on Monday, while the prominent upper ridge remains centered over the southern U.S. This pattern will continue an influx of subtropical moisture and broad mid-level instability across OR/ID, enabling high-based shower/thunderstorm development Monday afternoon. Low-levels will remain hot and dry, resulting in a lightning-outflow combination threat as activity develops. Current models favor E Oregon and the higher terrain of southwest and central Idaho, but NBM/WPC guidance has been under-representing the coverage of this threat. The aforementioned trough will begin to move onshore and pass north of the forecast area Tuesday and Wednesday. This will shunt moisture toward the east, limiting shower/thunderstorm chances to central and south-central Idaho for both days. Otherwise, anticipate hot and dry conditions for the remainder of the week. Afternoon breezes will develop each day through the extended, with Wednesday expected to be the gustiest day due to the passing trough.

AVIATION /06Z Friday through Saturday/

Issued 1204 AM MDT FRI JUL 3 2026

VFR. Isolated showers/thunderstorms developing around ID-NV border south of KTWF after Fri/19Z. Outflows 20-30 kt. Surface winds: light and variable, except N-NW 10-15 kt with gusts up to 25 kt between KBKE and KONO through early AM. Then, SW-NW 5-15 kt this afternoon. Winds aloft at 10kft MSL: W-SW 5-15 kt.

KBOI...VFR. Surface winds: light and variable/SE this AM, becoming NW-N 5-10 kt late morning/afternoon. Afternoon gusts around 15 kt.

Weekend Outlook...VFR with intermittent mid-high clouds. Slight chance of thunderstorms over central ID mtns and s-central OR Sunday afternoon. High density altitude in afternoons due to heat. Surface winds: SW-NW 5-15 kt Sat/Sun afternoons, light and variable overnights and mornings.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.