043
FXUS65 KBOI 290523
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1123 PM MDT Wed Oct 28 2026

.UPDATE...Updated aviation discussion.

&&

.KEY MESSAGES...
- Dry through Thursday, with near normal temperatures.

- Precipitation chances increasing across higher terrain Friday
  afternoon. Becoming widespread Saturday afternoon into Sunday.

- A drying and warming trend will set in Monday, through at
  least midweek.

&&

.SHORT TERM /Through Friday Night/...
Issued 205 PM MDT WED OCT 28 2026
Following the departing shortwave, skies have continued to
clear across southeast Oregon and southwest Idaho. With light
winds and mostly clear skies tonight, radiational cooling will
allow temperatures to drop into the upper 20s to mid 30s across
many lower valleys,resulting in areas of patchy frost late
tonight into Thursday morning.

A brief warming and drying trend will take hold on Thursday as
weak transient ridging moves overhead ahead of an approaching
upper level developing off the Pacific Northwest coast.
Afternoon temperatures on Thursday will rebound to near or
slightly above seasonal, with quiet weather prevailing across
the region through early Thursday evening.

Late Thursday night into early Friday, southwesterly flow aloft
will strengthen over the Great Basin and northern Intermountain
West.A weak shortwave trough embedded in this southwesterly
flow will lift northeastward across the area. While moisture
availability remains somewhat limited, sufficient moisture will
advect northward to south-central Idaho to support isolated to
scattered showers late Thursday night through Friday.

Snow levels will hover around 6000 to 7000 feet during morning
increasing to 8000 feet by afternoon. This will primarily yield
light rain in the lower valleys, but a dusting to a few inches
of snow possible across the higher peaks and mountain passes,
including Banner Summit. For the remainder of southwest Idaho
and southeast Oregon, Friday will feature passing cloud cover
and slightly cooler afternoon temperatures, with dry conditions
continuing through Friday night before the main Pacific trough
approaches for the weekend.

&&

.LONG TERM /Saturday through Wednesday/...
Issued 205 PM MDT WED OCT 28 2026
Saturday, a closed low with an elongated southern trough begins
to swing up and north of the forecast area, bringing the
trough, a cold front, and wetter conditions. This trough will
have a good pull of Pacific moisture ahead of it, with
precipitable water values increasing to around the 90th
percentile in southwest Idaho. The anomalous atmospheric
moisture will be coincident with largescale forcing, leading to
increasing precipitation chances through the day Saturday,
reaching 50-80% Saturday evening and night as a cold front
crosses the area. Hopefully your plan is to dress up as Mary
Poppins for Halloween, just in case. Snow levels will initially
begin at 6-8 kft MSL, lowering to 4.5-6.5 kft MSL by Sunday
afternoon. Lowering snow levels occur alongside decreasing
precipitation chances as conditions dry out behind the front.
Overall, the bulk of any snow accumulation will remain above 6.5
kft MSL, with generally 2-5 inches of accumulation (Locally up
to 7 on the highest peaks). The lowering snow levels could allow
for snow or wintry mix as low as 4.5 kft Sunday, although
little accumulation is anticipated as precipitation tapers off
behind the departing system. Ridging will build in behind the
departing system, allowing for dry conditions Monday afternoon
through at least mid-week. Temperatures will be seasonable or
below normal throughout the period.

&&

.AVIATION /06Z Thursday through Friday/...
Issued 1123 PM MDT WED OCT 28 2026

Generally VFR. Localized LIFR/IFR conditions with patchy freezing
fog and low stratus in high elevation valleys in southeast Oregon.
Mountains obscured in fog and low stratus. Surface winds: variable
less than 10 kt through morning, then NE-SE 5-15 kt by early PM.
Winds aloft at 10kft MSL: SW-S 20-30 kt.

KBOI...VFR. Increasing high cloud cover through the day. Surface
winds: E-SE 5-10 kt, with gusts to 20 kt by late morning.


&&

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

OR...None.

&&

$$

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