534
FXUS65 KBOI 110826
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
226 AM MDT Mon Aug 11 2025

.SHORT TERM...Today through Wednesday night...Very dry NW flow
aloft will continue today as a large closed upper high
retrogrades slowly well off the PacNW coast. While this will
allow 500 mb heights to fall slightly, surface pressures will
fall faster, resulting in increased "thickness" values and
therefore increasing temperatures. By Tuesday, readings will be
high enough above normal to warrant the issuance of an Extreme
Heat Watch for part of the area (generally SE Oregon and parts
of extreme west-southwest Idaho, see zone details below and/or
a map on our webpage). Although temperatures will decrease
enough Wednesday to eliminate the chance for a multiple-day
watch, it will still be above-normal, with mid to upper 90s
common at lower elevations. Our upper level flow becomes zonal
Tuesday into Tuesday night, then shifts to SW Wednesday. This
will begin to bring more moisture into the region Tuesday. A
chance of showers and thunderstorms officially returns to the
area Wednesday (specifically to southern Twin Falls and extreme
SE Owyhee counties). Although confidence is too low at this time
to add it to the forecast, I wouldn`t be too surprised if
isolated convection formed from Baker and northern Malheur
counties east through Valley County Tuesday late afternoon and
evening. For now, the chance is under 15%, and therefore won`t
be mentioned in our official forecast products.

.LONG TERM...Thursday through Monday...Upper level troughing
will move into position off the west coast of Canada Thursday
and remain there through the long term. This means our
southwest flow will also continue through the period. There`s a
slight chance of thunderstorms over at least part of the area
each day, and I would expect the areal coverage to increase as
we get closer in time and the models converge on the most likely
locations. This pattern is conducive to convection, and we will
simply await the return of sufficient moisture. Temperatures
are expected to be near normal each day.

&&

.AVIATION...VFR with clear skies. Surface winds: variable less
than 10 kt this morning, then N-NW 5-15 kt after 18Z. Winds
aloft at 10kft MSL: N-NW 10-20 kt.

KBOI...VFR with clear skies. Surface winds: variable 5 kt or
less this morning, then NW 5-10 kt with gusts to 15 kt after
18Z.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Extreme Heat Watch from Tuesday afternoon through Tuesday
     evening IDZ012-029-033.
OR...Extreme Heat Watch from Tuesday afternoon through Tuesday
     evening ORZ061-063-064.

&&

$$

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SHORT TERM...SP
LONG TERM....SP
AVIATION.....SP