Cuprum, Idaho Weather Forecast Discussion

018
FXUS65 KBOI 292032
AFDBOI
Area Forecast Discussion
National Weather Service Boise ID
232 PM MDT Mon Sep 29 2025
.SHORT TERM...Tonight through Wednesday night...The main Pacific
cold front will move eastward across the OR/ID border early this
evening, across western Idaho during the night, and exit east
of our CWA by sunrise. Showers and scattered thunderstorms (30
percent areal coverage) with local heavy rain as the front passes,
with a brief windshift to west or northwest 15 to 25 mph, then
several hours of steady moderate rain with light winds. Total
rainfall should be .50 inch to 1.00 inch in the Idaho mountains
(heaviest in the Boise Mountains), and .25 to .50 inch in the
Idaho valleys, with about half those amounts on the Oregon side.
Scattered light rain showers continuing Tuesday through
Wednesday mainly over northern mountains, with a slight chance
of thunderstorms in the afternoon and evening hours. Another
Pacific cold front with more showers expected Wednesday night.
.LONG TERM...Thursday through Monday...An upper low over the
coast of British Columbia will slowly break off and dig into
the Northwest region as a longwave trough through Thursday.
Southwest flow will be expected throughout the area Thursday and
Friday, with precipitation mostly concentrated along the western
Idaho side both days. A cooling trend is expected to continue
toward the end of the week, with peak valley temperatures
expected to gradually drop into the mid to lower 60s by Sunday.
Friday through Saturday will generally see the longwave trough
slowly dig southeastward across the region, but not signaling
much precipitation at this time. There is considerable uncertainty
over another upper low digging southward from British Columbia
or a longwave trough over the area Sunday through Monday. For
now, a drier and cooler pattern is expected for the weekend into
Monday.
&&
.AVIATION...VFR with isolated showers. Widespread showers and
scattered thunderstorms expected across the area today from 22Z
thru Tue/08Z. Embedded thunderstorms will produce locally heavy
rainfall and gusty outflow winds. Surface winds: E-SE 5-15 kt
in the Snake Plain, variable 10 kt or less elsewhere, with
gusts up to 20 kt. Winds aloft at 10kft MSL: S-SW 15-25 kt.
KBOI...VFR. Cold frontal passage around 02Z with thunderstorms,
followed by several hours of moderate rain, ending around
Tue/07Z. Surface winds: SE 5-15 kt, shifting briefly to NW
10-20kt as the front passes. Thunderstorm gusts 30 to 40 kt.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
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SHORT TERM...LC
LONG TERM....JY
AVIATION.....JY/LC

NWS BOI Office Area Forecast Discussion