191
FXUS65 KBOI 242010
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
210 PM MDT Sat May 24 2025

.SHORT TERM...Tonight through Monday night...Warm and dry
conditions will continue through Sunday as an upper-level ridge
remains in place ahead of an approaching trough and cold front
expected to arrive late Sunday. This pattern will drive
temperatures well above normal, with valley highs climbing into
the upper 80s on Sunday.

As the upper-level trough moves inland, it will serve as the
focus for thunderstorm development across parts of southeast
Oregon. Increasing instability along the front will support the
potential for stronger storms, with the highest chances (around
30%) across Harney and Baker Counties. Although the main axis of
instability and shear will remain northwest of the region,
model guidance indicates DCAPE values near 1000 J/kgsufficient
to support thunderstorm development. A few storms may produce
gusty outflow winds of 40 to 50 mph Sunday evening.

The trough will continue eastward Sunday night, maintaining a
chance for isolated showers and thunderstorms across southeast
Oregon. By Monday morning, the trough will shift into southwest
Idaho, bringing westerly to northwesterly winds and cooler
temperaturesroughly 7 to 9 degrees below Sundays highs.
Afternoon showers and thunderstorms may redevelop over the
higher terrain, especially along the Nevada-Idaho border, where
chances are near 30%. Dry conditions are expected to prevail in
the valley for Memorial Day.

.LONG TERM...Tuesday through Saturday...A high-amplitude upper
level ridge will begin to build in through Tuesday extending up
well into Canada by Wednesday. Some uncertainty is introduced
into the forecast come Wednesday thanks to a closed upper level
low in the Midwest CONUS. Some deterministic and ensemble
solutions resolve a shortwave swinging around the main upper
level low before closing off over our area. This introduces a
slight chance (15-25%) of precipitation across the Boise/West-
Central Mountains and Southwest ID highlands. Come Thursday,
deterministic and ensemble models show a negatively tilted
trough flattening down the ridge over our area. The question is
how deep will this trough get. The GFS solutions are more
aggressive bringing it across our area, while the EURO and ECWMF
AIFS keep it well north of us. If the GFS solution plays out,
it looks like a good ridge breakdown setup bringing
thunderstorms to the area. Have opted to introduce a slight
chance (20%) of thunder across higher terrain in the northern
parts of our area Thursday afternoon, as there is a good signal
across both ensembles for instability to build in Thursday (some
ensemble members even show >1000 j/kg of CAPE). The upper level
ridge builds back over our area Friday-Saturday, keeping our
area dry.

The atmosphere must be realizing it`s almost summertime as
temperature follow a warming trend Tuesday-Saturday. Increasing from
10 to 15 degrees above normal. The probability of reaching 90
degrees ranges from 40-75% (increasing as you follow the Snake Plane
from the western Magic valley into the Treasure Valley) Thursday-
Saturday.

&&

.AVIATION...VFR. Surface winds: W-NW 5-10 kt in the Snake Plain,
variable under 6 elsewhere. Becoming variable under 10 kt area-wide
tonight. Winds aloft at 10kft MSL: Variable under 10 kt.

KBOI...VFR. Surface winds W-NW 7-10 kt with an occasional gust up to
16 kt this afternoon. becoming SE under 8 kt overnight.

Sunday Outlook...VFR and mostly clear. Winds surface to 10kft MSL:
variable 5-15 kt.

&&

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

&&

$$

www.weather.gov/Boise

Interact with us via social media:
www.facebook.com/NWSBoise
www.x.com/NWSBoise

SHORT TERM...JDS
LONG TERM....NF
AVIATION.....NF