033
FXUS65 KBOI 300409
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
909 PM MST Sat Nov 29 2025

.DISCUSSION...A digging shortwave trough will bring a period of
light snow to the region late tonight. Touched up the forecast
through Sunday morning, mostly for a slight increase to
liquid/snow amounts over central Malheur County and higher
terrain south of the Snake Plain. Evening KBOI wx balloon
showing quite a bit of dry air (PW of 0.15") which will eat
snowfall to start. This will pair with surface temperatures
starting above freezing in much of the Snake Plain further
limiting snow accumulation. Most 00Z guidance keeps liquid
totals under 0.10" along the I-84 corridor (BKE-TWF) with
locally up to 0.20" to the south and west. In the Snake Plain a
dusting of snow (less than 0.5") on colder surfaces is the most
likely outcome, with the Twin Falls area seeing up to an inch.
Higher terrain from western Baker County through central
Malheur County to areas south of the Snake Plain are in line
for up to 2 inches of snow through noon Sunday.

&&

.AVIATION...Numerous snow/mixed showers moving from NW to SE,
exiting by late Sunday AM. MVFR to LIFR in precip. Mtns
obscured. Snow levels at/near valley floors. Surface winds:
variable less than 10 kt, except E-NE 10-15 kt with 20-30 kt
gusts from KMUO to KJER/KTWF. Winds transitioning to NW 5-15 kt
mid morning, with areas of 20-30 kt gusts. Winds aloft at 10kft
MSL: NW-NE 15-30 kt.

KBOI...VFR tonight, then a 70% chance of light snow between
Sun/08Z-13Z. Some uncertainty since snow will need to overcome
the dry air near the surface, but light accumulations of trace
to half inch possible on cold surfaces. Brief MVFR-IFR in snow
and foothills obscured. Surface winds: light and variable, then
W to NW 5-12 kt after Sun/09Z. Gusts to around 20 kt by late Sun
morning into afternoon.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Monday night...High clouds
continue to stream in from the northwest today as the next
system moves into the area late this evening. Cool dry air
continues to trickle down the Snake Plain today. East-
southeast winds 10-20 mph this afternoon in the Snake Plain.
Snow showers increase late this evening in eastern OR and
overnight into Sunday morning in southwest ID as a weak system
moves across the area. Cool dry air in the Snake Basin from east
to southeast flow will limit snow amounts to under an inch due
to sublimination in the low levels, while the higher terrain
will generally see 1-2 inches of new snow. Snow showers taper
off by Sunday afternoon with lingering low clouds and fog.
Breezy northwest winds follow the system during the afternoon
with clearing. Patchy fog possible on Monday morning. High
clouds expected Monday afternoon with light winds. Next system
arrives late Monday with showers developing in eastern OR late
in the evening.

LONG TERM...Tuesday through Saturday...Come Tuesday, an upper
level trough will dig down across our area from British
Columbia. A consequence of this system digging down from
mainland British Columbia is that moisture will be limited, with
it removed from any Pacific moisture. None the less, this
system will support precipitation chances of 30-50% in valleys,
and 50-90% across higher terrain. With snow levels near valley
floors Tuesday morning, Mountains could see 1-2 inches of
additional snowfall with valley locations seeing a wintery mix.
Ensembles have been pretty consistent the past few runs of
putting down a measurable snowfall in the Treasure and western
Magic Valleys on Tuesday. However limited accumulation is
expected, and any snow that does accumulate will melt off pretty
quickly with daytime highs climbing to the low 40s. Breezy
conditions will also accompany this system Tuesday afternoon.

As this system exits, an amplified pattern will remain with a
high amplitude ridge off the west coast and troughing over the
central/eastern CONUS, leaving our area under dry
north/northwest flow. This flow will keep temperatures right
around normal for this time of year in lower elevations,
although upper-level subsidence will keep mountain temps leaning
above normal. Uncertainty remains on when the ridge will begin
to breakdown and when we can tap into some moisture, but it`s
looking like sometime late this coming week is favored. The Euro
and GFS ensembles have an uptick in moisture, ensemble mean
values around the 90-95th percentile, but timing varies with the
GFS bringing it in Friday and the Euro lagging it towards
Saturday. This is resulting in increasing precipitation chances
through Friday and into Saturday. Precipitations Friday
afternoon are 20-50% generally confined north of the Snake
Plain, expanding and increasing to 10-20% in and south of the
Snake Plain with a 30-70% chance north (highest in the west
Central Mountains). Temperatures Friday/Saturday will begin to
lean above normal in lower elevations (staying above normal in
higher elevations as well), with snow levels rising to 5-6kft
MSL.

&&

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

&&

$$

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DISCUSSION...DG
AVIATION.....SH
SHORT TERM...KA
LONG TERM....NF