016
FXUS65 KBOI 192000
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
200 PM MDT Wed Aug 19 2026

.KEY MESSAGES...
- Heat Advisory Thursday afternoon through Friday in the
  Treasure Valley, western Magic Valley, and Upper Weiser
  River Valley.

- Increased chance of afternoon and evening showers and
  thunderstorms over higher terrain Friday through Sunday.

- Above normal temperatures next week with a chance of
  afternoon thunderstorms each day over the mountains of
  southwest Idaho.

&&

.SHORT TERM /Through Friday Night/...
Heat Advisory continues in effect Thursday afternoon through Friday
sunset as originally issued for the Snake Basin and Upper Weiser River
Valley evening.  However, high temps Friday have been adjusted down
a couple degrees due to increasing clouds, especially on the Oregon
side. Patchy smoke from wildfires will continue in eastern Oregon
and northern mountains in Idaho with Friday morning the worst,
although not nearly as smoky as 10 to 15 days ago.  The first minor
influx of monsoon moisture will bring isolated thunderstorms to
northeast NV late today. Storms should stay south of ID but gusty
outflow winds may reach southern Twin Falls County.  A slightly
stronger moisture surge will bring a 20% chance of showers and
thunderstorms to Twin Falls County Thursday afternoon and evening.
However, Friday is the day to watch as monsoon moisture increases
further under stronger southwesterly flow aloft, due to a Pacific
upper trough nearing the northwest coast.  On that day after a very
hot afternoon there will be a 20-30 percent chance of thunderstorms
in eastern-most Idaho zones, and with lower atmospheric layers still
dry these storms will again feature gusty winds and little rain.

&&

.LONG TERM /Saturday through Wednesday/...
An upper trough moving across the PacNW on Saturday will bring a
cold front and associated strong winds and increased thunderstorm
chances. Wind gusts on Saturday increase to 20-35 mph across the
area, highest in SE Oregon where minimum relative humidities around
10-20% will cause elevated fire weather conditions even though
temperatures are cooler than Friday. Increased moisture ahead of
the trough is amplified as it approaches, supporting a 20-50%
chance of afternoon and evening thunderstorms across West Central
and South Central Idaho, especially over the mountains. Storm
chances stretch into the Blue Mtns of Eastern Oregon as well.
Storms could produce lightning, strong gusty winds, and brief
heavy rainfall.

The remainder of the extended period will be defined by the
persistent Four Corners ridge which will place our region under
southwest flow. Near normal temperatures Sunday, will be on the
rise next week as the ridge rebounds. Latent monsoonal moisture
circling the ridge maintains a 10-20% chance of storms and showers
in South Central Idaho Sunday through Wednesday.

&&

.AVIATION /18Z Wednesday through Thursday/...
Issued 1131 AM MDT WED AUG 19 2026
VFR under mostly clear skies. Areas of wildfire smoke across
NE Oregon this afternoon. Surface winds: less than 10kt through
tonight. Winds aloft at 10kft MSL: S 10-15 kt.

KBOI...VFR under mostly clear skies. Light surface winds through
Wednesday.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Heat Advisory from noon Thursday to 9 PM MDT Friday for IDZ012-
     014-016-033.
OR...Heat Advisory from noon MDT /11 AM PDT/ Thursday to 9 PM MDT
     /8 PM PDT/ Friday for ORZ064.
&&

$$

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SHORT TERM...LC
LONG TERM....JM
AVIATION.....LC