107
FXUS65 KBOI 101656
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
956 AM MST Wed Dec 10 2025

.DISCUSSION...
SHORT TERM UPDATE...Today through Thursday afternoon...Lifting
warm front over the area will continue weak precipitation
episodes over the West-Central ID mountains this morning,
before tapering off through the early afternoon. Low clouds
remaining over the central mountains of Eastern OR/Western ID
and Upper Treasure Valley, expected to lift in the early
afternoon. Dense fog advisory remains over Baker County OR until
18Z (10 AM PST), as diurnal heating is expected to dissipate
the fog. Today will continue to see the warmest temperatures of
the week, with peak temperatures in the lower 60s over lower
elevations and in the upper 40s/mid 50s over higher elevations.
Winds are expected to remain SE-SW under 10 kt for most areas,
except slightly higher in Magic Valley with afternoon gusts up
to 20 kt.


Tomorrow will see a very slim cooldown into the upper 50s for
lower elevations and lower to mid 40s for higher elevations.
Light rain episodes possible for Northern Baker County OR and
most of Valley County ID tomorrow. Mostly dry otherwise with
clearing skies over the lower elevation valleys. There is
potential for valley inversions tomorrow afternoon, depending on
how low the mixing heights drop and how weak the winds
maintain.



&&

.AVIATION...Mainly VFR with scattered to broken clouds. Isolated
MVFR to LIFR conditions in Patchy fog/Stratus in sheltered valleys
dissipating by 19z. Mountains obscured. Surface winds: SW-SE 5-15 kt
with gusts 15-30 kt, except lighter in the Snake Basin outside of
the Magic Valley. Winds aloft at 10kft MSL: W-NW 35-45 kt.

KBOI...VFR with decreasing clouds. Surface winds: SE 4-8 kt.

&&

.AIR STAGNATION...A broad upper-level ridge over the eastern
Pacific and western US is expected to strengthen in our area for
the remainder of the week and through the weekend, causing
mixing heights to lower to 1,500 to 2,000 feet AGL Thursday and
1,200 to 1,700 feet AGL Friday through Sunday. At the same time,
winds are expected to be less than 10 mph resulting in
sustained poor ventilation. An Air Stagnation Advisory is being
considered for Thursday through Sunday. More on that later
today.


&&

.PREV DISCUSSION...
SHORT TERM...Today through Friday night...The atmospheric river
has shifted completely north of our CWA, faster than yesterday`s
models predicted. Latest models have adjusted accordingly. Radar
at 2 AM MST still showed a few light showers or sprinkles in
northern zones but south of the atmospheric river and of little
impact. Today`s forecast has lower PoPs and less QPF than before,
and after today only our northern-most mountains will have any
chance of pcpn. The drier forecast will ease concern about
rising rivers, and will also allow slightly warmer high temps
than previously forecast, which was already 15-20 degrees above
normal. Today should be the warmest day this week, with Thursday
and Friday only slightly cooler. Partial clearing tonight will
allow several degrees colder temps than the past two nights, and
patchy fog in southern areas. West/southwest winds will gust
20-30 mph in the Snake Basin this afternoon. Otherwise, only
light south- southwest winds through Friday night.

LONG TERM...Saturday through Wednesday...High pressure over the
area through Sunday will keep our area dry under partly cloudy
skies. While dry, this high pressure will introduce the potential
for fog/low stratus under a temperature inversion The inversion
will be marked with mixing heights staying below 1500ft AGL.
With the fog/low stratus potential, and cooler air likely
getting trapped under the inversion, some uncertainty remains
in regard to the weekend temperatures. However, with the warm
airmass in place, above normal temperatures are likely even with
the potential cold pooling. Temperatures throughout the long
term period will be 10-15 degrees above normal. Cloud cover will
begin to increase throughout the day Monday ahead of the next
system.

Speaking of the aforementioned next system, there continues to
be uncertainty regarding the exact timing of it. The GFS ensemble
suite continues to lag a little behind the Euro ensemble suite;
although both suites show it coming through our area early next
week. This is leading to increasing precipitation chances
starting Monday afternoon, increasing to a 55-70% chance north
of the Snake Plain and 50-25% chance in and south of the Snake
Plain by Monday evening. This initial system will mark the start
of a more unsettled pattern throughout the long-term period.
The Grand ensemble favors zonal-flow over our area through at
least Wednesday, which would place our area under the favored
storm track. With this, precipitation chances remain elevated
through Wednesday. Unfortunately for winter lovers, this pattern
doesn`t look too good for getting colder temps and snowfall.
Without much (if any) northerly component to the flow,
temperatures will remain mild and above average through the
period. This is also reflected in the snow levels, hovering
between 5-8kft MSL Monday through Wednesday.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...Dense Fog Advisory until 10 AM PST this morning ORZ062.

&&

$$

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DISCUSSION...JY
AVIATION.....JDS
AIR STAGNATION...JY
SHORT TERM...LC
LONG TERM....NF