947
FXUS65 KBOI 180903
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
303 AM MDT Sat Oct 18 2025

.SHORT TERM...Today through Monday night...Weak ridging today
ahead of the next system for Sunday will bring warm and dry
conditions. As we enter inversion season, mountains will tap
into warming aloft as high temperatures rise 2 to 5 degrees over
yesterday`s, while sheltered mountain valleys and lower
elevations will see high temperatures remain unchanged or even a
couple of degrees cooler than today.

The next system approaches the Pacific Northwest coast today
and will push eastward with a cold frontal passage on Sunday.
The frontal passage across the area is expected between 7 AM MDT
and 3 PM MDT Sunday, with no significant change seen in the
guidance. The greatest confidence for precipitation remains
across the mountains of east central Oregon and west central
Idaho. Confidence is lower across central Malheur, Harney
counties, and the lower Snake Plain, due to a large variance in
high res guidance which has been reflected in the forecast with
a low chance (15 to 20 percent) for showers developing along the
front in these areas. Areas along the Nevada border look to
remain dry through the weekend. Snow levels will drop behind the
front on Sunday, allowing for minor accumulations (less than 2
inches) above 6500 to 7000 feet.

Southerly winds will pick up ahead of the front on Sunday,
mostly across higher terrain where gusts of 20 to 30 mph are
expected. The frontal passage Sunday afternoon brings a wind
shift to the west northwest and increases the gust potential to
25 to 40 mph across the entire area. Showers will continue
across the west central mountains of Idaho into Monday under
cool and breezy northwesterly flow. This will keep temperatures
about 5 to 7 degrees below normal.

.LONG TERM...Tuesday through Saturday...A ridge of high
pressure will build over the Intermountain West Tuesday through
Friday morning, bringing slightly above normal temperatures and
dry conditions to the region. Temperatures will be in the upper
60s to low 70s on Thursday and Friday in valley locations with
light winds across the area.

A significant change looks to move in late Friday, with a trough
over the Gulf of Alaska deepening bringing an atmospheric river
into the Pacific Northwest. This will bring breezy winds and
widespread precipitation into the region late Friday into
Saturday. Southwest flow ahead of the main cold frontal passage
on Saturday will keep snow levels elevated around 7000-8000
feet. This will drop and lead to a higher potential for heavy
mountain snow accumulations by late Saturday. Model agreement
remains high in the passage of this system, but there remains
discontinuity in precipitation totals and timing with ensemble
and deterministic solutions.

&&

.AVIATION...VFR. Low confidence in scattered stratus deck near
KBOI- KONO and near KBKE. Areas of LLWS over the Magic Valley
early this morning. Surface winds: W-NW 5-15 kt with occasional
gusts to 25 kt, dropping to SW-W 5-10 kt by Sat/10Z then
becoming E-SE 5-15 kt after Sun/00Z. Winds aloft at 10kft MSL:
W-NW 20-40 kt.

KBOI...VFR with a few low stratus clouds this morning. Surface
winds: variable becoming NW-W 8-12 kt becoming SE 5-8 kt after
Sat/22Z.

Sunday Outlook...Increasing clouds with scattered showers north
of a KBNO-KMUO line after Sun/12Z. Snow levels during precip
drop from 9000 ft MSL to 5500 ft MSL by Sun evening. Surface
winds: SW-SE 10- 20 kt with gusts up to 40 kt.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Frost Advisory until 9 AM MDT this morning IDZ012-014-016.
OR...Frost Advisory until 9 AM MDT /8 AM PDT/ this morning ORZ064.

&&

$$

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SHORT TERM...JDS
LONG TERM....SA
AVIATION.....SA