Emmett Weather

487
FXUS65 KBOI 310435
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
935 PM MST Fri Jan 30 2026

.DISCUSSION...Moist southwest flow aloft will continue feeding a
mostly uninterrupted stream of mid-high clouds over the region
this weekend. There will be times when they thin out or briefly
break, but overall we`ll keep a cloud cover. Near the surface,
valleys remain in a temperature inversion and on the verge of
fog each night. The clouds hanging out overhead will keep
formation isolated to the lower Snake Plain and mtn valleys.
Have updated forecast for fog and sky cover tonight.

&&

.AVIATION...Mostly VFR under mid-high ceilings overnight. Low
VFR-MVFR in haze/mist at lower elevations, especially SE Oregon
and Snake Plain of ID west of KMUO. Brief IFR conditions again
Saturday morning from vicinity of KBOI-KONO-KBNO, improving
after 15-17Z. Surface winds: variable up to 10 kt. Winds aloft
at 10kft MSL: W 15-25 kt.

KBOI...VFR. Patchy fog in the vicinity of the terminal
Sat/10Z-17Z could bring brief IFR conditions. Light surface
winds.

Weekend Outlook...Mostly VFR with high clouds and dry conditions
through the weekend. Sheltered valleys will see IFR-LIFR conditions
each night/morning in fog and low stratus. Surface winds will be
light overnight, and easterly up to 15 kt during the day.

&&

.AIR STAGNATION...Lower valleys are having trouble mixing out,
possibly due to high cloud cover limiting surface heating. The
NBM seems to be under-forecasting high clouds and over-
forecasting afternoon mixing heights. Easterly winds did help
with mixing across valleys/basins in SE Oregon and areas east of
Boise in the Snake Plain today. It doesn`t look like we`ll see
much change through the weekend. Higher valleys will improvement
on Monday with passage of a weak low pressure system, but it`s
uncertain if this system will be enough to break out the lower
Snake Plain. From there, the stagnant conditions will rebuild as
high pressure strengthens aloft.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Sunday night...A ridge remains
over the area with high clouds streaming into the area from a
system impacting British Columbia and WA. Temperatures will warm
a few degrees on Saturday, especially at the higher elevations,
although high clouds will be working against the warmer
temperatures. High resolution ensembles show temperatures
reaching the low to mid 50s across eastern OR and portions of
the Snake Basin over the next several days. Low clouds and fog
will persist in the lower Treasure Valley until late afternoon
where temperatures will be slightly cooler each day. Patchy fog
expected each night in the lower Treasure Valley.

LONG TERM...Monday through Friday...A shortwave trough to our north
will dampen the ridge of high pressure on Monday. Recent forecasts
show increasing confidence in the lack of showers and tangible
impacts in our region from this trough passage, other than keeping
temperatures somewhat cool and bringing cloudy skies on Monday. The
ridge will rise yet again over our region by Tuesday, bringing a non-
zero chance of warming temperatures. These will be dependent on the
valley inversions that set up over the area. If we have enough
mixing and clearing from day to day, we might be able to achieve
temperatures in the 50s in the Snake River Valley and near the
Nevada border. However, this upper level pattern of stationary high
pressure favors valley inversions forming in the winter. This would
bring a return to stagnant conditions with patchy fog, low stratus
cloud decks, trapped pollutants, and lower elevation cold pools,
with high temperatures in the upper 30s to low 40s. This is the more
likely outcome based on this pattern, but there is a potential for
the strength of this high to create significant mixing that might
keep us warmer than anticipated. This blocking high remains through
the work week, with some AI ensembles indicating a cooler and wetter
shift to the pattern by the weekend.

&&

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

&&

$$

www.weather.gov/Boise

Interact with us via social media:
www.facebook.com/NWSBoise
www.x.com/NWSBoise

DISCUSSION...DG
AVIATION.....DG
AIR STAGNATION...DG
SHORT TERM...KA
LONG TERM....SA