284
FXUS65 KBOI 151815
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1215 PM MDT Wed Jul 15 2026

.UPDATE...Updated aviation discussion.

&&

.KEY MESSAGES...
- Chance of showers and thunderstorms mostly over higher terrain
  through Friday.

- Hot temperatures into the upcoming weekend with valley highs
  around 100 degrees.

&&

.SHORT TERM /Through Friday Night/...
Issued 312 AM MDT WED JUL 15 2026
A weak shortwave trough and lingering monsoonal moisture are
generating isolated thunderstorms over central Oregon and
portions of southern Idaho early this morning. Localized wind
gusts up to 40 mph have been associated with the thunderstorm
cluster near the ID-NV border. Activity is expected to taper
off by mid-morning as the shortwave exits to the northeast.
Later today, a broad Pacific trough along the west coast will
shift inland today, nudging the bulk of the monsoonal moisture
toward the east. However, residual mid-level moisture and
synoptic lift will trigger the next round of isolated showers
and thunderstorms this afternoon across central/east Oregon and
higher terrain of SW Idaho. Enhanced diurnal heating and drying
low-levels will increase the potential for thunderstorm outflow
wind gusts to 30-45 mph. Outside of storms, the clearer skies
and drying conditions will encourage hotter afternoon temperatures
compared to Tuesday.

On Thursday, the Pacific trough will track northeast into BC
Canada, allowing the large high pressure dome over the central
U.S. to re-build westward. This pattern shift will carry the
monsoon moisture back west, resulting in more shower and
thunderstorm activity across southwest Idaho both Thursday and
Friday afternoons. Additionally, the building ridge will heat
temperatures further, with lower elevations reaching or exceeding
100 degrees both days.

&&

.LONG TERM /Saturday through Wednesday/...
Issued 312 AM MDT WED JUL 15 2026
Southwest flow aloft will dominate the long term pattern as
prominent high pressure remains stationary over the the central
U.S. This will maintain an influx of monsoonal moisture,
resulting in continual rounds of afternoon showers and
thunderstorms across southern/central Idaho and portions of E
Oregon. Hot temperatures will persist at approximately 5-10
degrees above normal each afternoon. As a result, broad areas
of moderate-level Heat Risk are expected for lower elevations
and mountain valleys, affecting individuals sensitive to heat.
Toward mid-week, a few model members attempt to flatten the
ridge, which would transition the upper flow to more westerly
and reduce temperatures/storm activity. However, forecast
confidence remains low at this time.

&&

.AVIATION /18Z Wednesday through Thursday/...
Issued 1207 PM MDT WED JUL 15 2026
VFR with scattered cumulus development over higher terrain
through sunset. Widely scattered showers and thunderstorms over
SE Oregon and SW Idaho mtns will produce gusty outflow winds to
40 kt. Surface winds: variable up to 10 kt with localized gusts
to 15 kt. Winds aloft at 10kft MSL: Southerly 5 to 15 kt.

KBOI...VFR with northwest winds through sunset.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.

OR...None.

&&

$$

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AVIATION.....DG
SHORT TERM...SH
LONG TERM....SH