Mora, Idaho Weather Forecast Discussion

404
FXUS65 KBOI 291559
AFDBOI
Area Forecast Discussion
National Weather Service Boise ID
955 AM MDT Mon Sep 29 2025
.DISCUSSION...No changes needed to current forecast, with
the Pacific cold front still slated to reach the OR/ID
around 6 PM MDT and shift eastward across our Idaho zones
during the night. A 30 percent chance of thunderstorms
still forecast as the front passes, then several hours of
moderate rain on the Idaho side tonight resulting in .20
to .50 inch total rainfall in the valleys, and up to 1.00
inch in the mountains, greatest in the Boise Mountains.
The rain shield should be completely east of our CWA
by sunrise Tuesday, but scattered lighter rain showers
will continue or re-develop in northern mountains later
Tuesday, with a 10 to 20 percent chance of weak
thunderstorms in the afternoon. Also, 6 to 12 degrees
cooler Tuesday compared to today.
&&
.AVIATION...VFR with isolated showers. Rain band currently
developing in SE OR and moving into SW ID. Later, widespread
showers and scattered thunderstorms will develop across the
area today around 20Z through Tue/08Z. Thunderstorms embedded
in lines of showers could produce locally heavy rainfall and
gusty outflow winds 30-40 kt. Surface winds: E-SE 5-15 kt in
the Snake Plain, elsewhere variable 10 kt or less, with gusts
up to 20 kt through the afternoon.  Winds aloft at 10kft MSL:
S-SW 15-25 kt.
KBOI...VFR. Scattered light rain showers this afternoon until
Tue/02Z. Cold frontal passage around 02Z with thunderstorms,
followed by several hours of light to moderate rain, decreasing
Tue/07Z. Surface winds: SE 5-15 kt, shifting briefly to NW as
the front passes. Thunderstorm gusts 30 to 40 kt.
&&
.PREV DISCUSSION...
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 time-frame 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 will
be 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
other than 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 will drop slightly to 5-10 degrees below normal Sunday
and Monday. Given model agreement on the amplification of the
Sun/Mon low, it is likely that temps will continue the downward
trend after Monday.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
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DISCUSSION...LC
AVIATION.....JY
SHORT TERM...DG
LONG TERM....JM

NWS BOI Office Area Forecast Discussion