250
FXUS65 KBOI 222107
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
207 PM MST Wed Jan 22 2025

.SHORT TERM...Tonight through Friday night...Cold temperatures
are expected again tonight, though overall lows will be slightly
warmer compared to last night. The coldest areas will be
sheltered valleys with snow cover, where temperatures may drop
below zero.

An upper-level ridge will begin to flatten on Thursday as an
approaching upper-level trough moves in. This shift will lead to
improved mixing and warmer temperatures Thursday afternoon,
nearing seasonal averages for the Western Snake River Plain.

A weak surface cold front is on track to move from north to
south on Friday, ushering in colder conditions under a northerly
flow for the weekend. Light snow is forecasted for the central
and eastern Idaho mountains, with accumulations of up to one
inch. In southern regions, light snow is possible Friday night
due to the upper trough, with less than an inch expected in the
mountains and flurries or a light dusting in the valleys.
Current models suggest only about a 6% chance of valley snow
accumulation reaching a tenth of an inch or more. Breezy north-
northwesterly winds behind the front will make Friday afternoon
and evening feel particularly chilly.

.LONG TERM...Saturday through Wednesday...Very little change to the
latest models/ensembles. It still appears that an upper level trough
axis will move through Saturday, followed by ridging building in
from the NW. An inversion will likely develop as a result, and
temperatures were again modified in the long term period (colder in
the valleys). Model agreement is above-average, and therefore
confidence is high. Air stagnation due to low mixing heights and
light winds will develop early next week.

&&

.AVIATION...VFR. Surface winds: variable 10 kt or less, becoming SE
5-10 kt after 23/06Z. Winds aloft at 10kft MSL: NW-N 25-35 kt.

KBOI...VFR. Surface winds: NW 5-10 kt this afternoon, becoming SE 5-
10 kt after 23/06Z.

&&

.AIR STAGNATION...Temporary air stagnation with mixing height
near the threshold value of 2kft MSL is expected through
Thursday, then deeper mixing behind a cold front Friday through
the weekend. The next air stagnation event is likely beginning
Monday as high pressure aloft brings warmer air to higher
elevations while cold air continues in most of the valleys.

&&

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

&&

$$

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SHORT TERM...JDS
LONG TERM....SP
AVIATION.....SP
AIR STAGNATION...JDS