Crouch, Idaho Weather Forecast Discussion

898
FXUS65 KBOI 290904
AFDBOI
Area Forecast Discussion
National Weather Service Boise ID
304 AM MDT Mon Sep 29 2025
.SHORT TERM...Today through Wednesday night...The leading edge
of a broad upper trough will push a cold front through the
region this afternoon/evening. Showers and thunderstorms will
develop ahead of the front by early afternoon, with the threat
continuing through late evening as the front tracks across SW
Idaho. Wind gusts to 40 mph are possible from showers and
storms with locally heavy rain amounts from stronger storms. The
larger rain totals through tonight continue to line up over SW
Idaho, generally east of a line from the ID/OR/NV triple point,
through Idaho City and Warm Lake. Areas east of this line are
looking at 0.25-0.50" totals in the Snake Plain with 0.50-1.0"
amounts in the mountains. Otherwise 0.10-0.25" with local 0.50"
amounts are expected across SE Oregon and the lower Snake Plain
through tonight.
The trough axis remains offshore, keeping the region under
southwest flow aloft through Wednesday. Mountains will hold onto
a 30-60% chance of precipitation during this time while
southeast Oregon and lower elevations of SW Idaho trend drier with
probabilities in the 10-25% range. The atmosphere will hold
enough instability to support thunderstorm potential on Tuesday,
with cloudy and more stable conditions diminishing the threat
on Wednesday. Precipitation amounts during this period will be
lighter with less than 0.10" across lower elevations and up to
0.25" in the mtns. Temperatures step down 3-6 degrees each day
with highs around normal on Wednesday (valleys low 70s, mtns
upper 50s). Snow levels remain above 8kft MSL through Wednesday
night.
.LONG TERM...Thursday through Monday...The unsettled pattern
continues through Friday as the core of a Pacific low finally
swings through the area. It moves quickly once making
landfall, so only the short timeframe Thursday through Friday
morning is affected. Thursday afternoon, higher elevations and
s-central Idaho will see precipitation chances around 20 to 40%,
correlated strongly with elevation. Right before the core of
the low moves overhead, strong moisture flow Thursday evening
and night is centered over the Magic Valley and s-central Idaho.
While this will bring 0.1-0.2" of rainfall, the band of rain is
narrow, and could easily shift in coming model runs. As the
core of the low moves overhead Friday afternoon, precip chances
drop drastically.
Skies remain cloudy behind the strong trough, and while another
wave begins to develop for Sunday, unfavorable moisture flow
among ensemble means hints at a low chance for further precip
outside of virga and very light rainfall amounts in the
mountains. This secondary wave will however stall and amplify
directly over the region Monday, increasing chances of
precipitation in the eastern portions of our area, but also
continuing the cooling trend. Temps about 5 degrees below normal
Thursday through Saturday drop slightly to 5-10 degrees below
normal Sunday and Monday. Given model agreement on the
amplification of the Sun/Mon low, it seems likely that temps
could continue the downward trend after Monday.
&&
.AVIATION...VFR with isolated showers in SE OR. Rain band
develops in SE-E OR Mon/15Z, that slowly moves eastward to
KONO by Mon/20Z. Later, widespread showers and scattered
thunderstorms develop across the area Mon/20Z thru Tue/08Z.
Thunderstorms embedded in showers could produce locally heavy
rainfall and gusty outflow winds to 35 kt. The main afternoon
thunderstorm band moves eastward from KBNO at Mon/23Z to KBOI at
Tue/03Z to KTWF at Tue/07Z before it moves out of our forecast
area. Surface winds: E-SE 5-15 kts in the Snake Plain, elsewhere
variable 10 kts or less. Winds aloft at 10kft MSL: S-SW 15- 25
kts.
KBOI...VFR with scattered high clouds overnight. Rain showers
Monday afternoon through midnight, with a period of heavy rain,
gusty winds, and thunder possible Mon/22Z thru Tue/06Z. Surface
winds: SE 5-15 kts.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
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SHORT TERM...DG
LONG TERM....JM
AVIATION.....JM

NWS BOI Office Area Forecast Discussion