Garden City, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

027
FXUS65 KBOI 151545
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
945 AM MDT Fri Aug 15 2025

.DISCUSSION...Cooler temperatures are in place today ahead of a
well-defined low pressure system located off the British
Columbia coast. Isolated thunderstorms are expected to redevelop
this afternoon and evening in southern Twin Falls County along
the western edge of monsoon moisture. The strongest storms will
be capable of producing gusty winds up to 50 mph. Southwesterly
winds aloft have kept smoke from the Rock Fire to the northeast
of the region.

Moisture continues to increase across the area, with
precipitable water values reaching 0.82 inches based on the 12Z
BOI sounding. This is in the 80th percentile for mid-August, and
the bulk of deeper moisture is expected this weekend. Current
model guidance is under doing the existing moisture, suggesting
it may be underestimating the potential for thunderstorms on
Saturday. Some high-resolution guidance indicates convection
developing ahead of the approaching cold front across southeast
Oregon into the west-central mountains of Idaho Saturday
afternoon. Modest instability near 600 J/kg and shear around 30
knots would support storms with greater longevity. Given the
elevated moisture, these storms will be capable of producing
heavy rainfall and small hail. The forecast has been updated to
reflect higher precipitation chances for Saturday across the
areas mentioned above.

&&

.AVIATION...Mostly VFR. Local visibility restrictions due
to wildfire smoke, mainly in the w-central Idaho mountains
including McCall and Cascade. Showers/storms will develop near,
south, and east of the Magic Valley this afternoon, with
outflows up to 40 kt possible. Surface winds: mainly W-NW 5-15
kt. Winds aloft at 10kft MSL: W-S 5-15 kt.

KBOI...VFR. W-NW surface winds less than 10 kt.

Weekend Outlook...Mostly VFR. Reduced visibility in smoke across
the w-central Idaho mountains. Scattered afternoon showers and
thunderstorms each day, mostly over SE Oregon and higher terrain
of SW Idaho, producing gusty outflow winds and locally heavy
rain. Surface winds generally W-NW 5-15 kt.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Sunday night...Isolated thunderstorms
will again develop this afternoon and evening in southern Twin
Falls County on the western edge of monsoon moisture. An unusually
well-developed frontal system in the Gulf of Alaska has already
spread showers into western WA but will weaken as it moves
further inland. A 30-50 percent chance of showers will finally
reach western Baker County and northwestern Harney County
Saturday afternoon, with instability also allowing a 10-20
percent chance of thunderstorms. Showers and storms will make
little further eastward progress Saturday night, getting into
the west central Idaho mountains but barely reaching the
southwest Idaho border. On Sunday afternoon a short wave
trough rounding the base of the main upper trough in the
eastern Pacific will develop showers and a slight chance of
thunderstorms over the higher terrain of western Idaho in
addition to continuing showers and storms near the stalled
and weakening frontal zone in eastern Oregon. These showers
and storms should continue Sunday night but end toward
morning as the front shifts gradually northward again as
a barely discernible warm front.

LONG TERM...Monday through Friday...The weak warm front will
move north of our CWA Monday with drier and warmer weather
coming in from the south. An upper high over CO and NM will
shift westward to the UT/CO border Tuesday and circulate hotter
air into our CWA from the south. Southern ID valleys will
approach 100 degrees again Thursday and Friday. Winds aloft
will also bring mid-level monsoon moisture into southern Idaho
but models hesitate to introduce thunderstorms until Friday
afternoon.

&&

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

&&

$$

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DISCUSSION...JDS
AVIATION.....JDS
SHORT TERM...LC
LONG TERM....LC