Nampa, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

492
FXUS65 KBOI 301605
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1005 AM MDT Sun Mar 30 2025

.DISCUSSION...Patchy dense fog was reported in the Lower
Treasure Valley, Upper Weiser Basin, and Long Valley (McCall,
this morning. The fog will dissipate by noon. Light
precipitation along a warm front moves through SE Oregon later
this afternoon and SW Idaho this evening. The front will be
followed by unstable conditions, leading to scattered showers
and isolated thunderstorms. Some of the storms could produce
gusty winds and small hail/graupel. Snow levels rise from 3000
feet this morning to around 5000 feet this afternoon with light
snowfall accumulations in the mountains. Forecast was updated
earlier due to the fog.

&&

.AVIATION...Mostly VFR. Localized fog creating LIFR conditions
at KONO and will lift by late morning. Band of showers will
enter SE Oregon after 30/18Z and move northeastward, with a
slight chance of thunderstorms beginning around 30/22Z and
lasting through the night. Mountains obscured at times. Surface
winds: E-S 5-15 kt. Gusts 15-25 kt in SE Oregon. Winds aloft at
10kft: SW 20-40 kt.

KBOI...VFR. Periods of clouds throughout the morning. Showers
expected to develop after 30/22Z. 10% chance of a thunderstorm
from 31/00Z to 31/06Z. Surface winds: SE 10-15 kt.

&&

.HYDROLOGY...Cool showery conditions will continue through
most of the upcoming week. Snow levels will remain low, and
heavy precipitation is not expected at this time. However, minor
flooding is forecast to continue on the Silvies River near
Burns and Malheur River near Vale through the week.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Tuesday night...Another storm system
is set to impact the region later today, beginning with a warm
frontal passage, followed by widespread precipitation and a
significant drop in temperatures on Monday as a cold front moves
through. Additionally, there is a chance for a rain-snow mix in
the Snake River Plain early Tuesday morning. With clearer skies
and light winds following yesterdays precipitation, conditions
are favorable for valley fog development toward sunrise. Fog
has already formed in Long Valley, and there is at least a 30%
chance of fog in Baker Valley and the Treasure Valley.

As of 2 AM MDT, the incoming storm system is positioned near
42N and 135W, approaching the Pacific Northwest with a strong
warm front extending to the northern California coast. This
front will push northeastward today, reaching the Nevada-Oregon
border around noon MDT, the Snake River Plain and Baker Valley
by 4 PM MDT, and the central Idaho mountains by 6 PM MDT. A band
of light precipitation is expected along the front as it moves
through. Post-frontal convective showers, and possibly a few
thunderstorms, may develop, though instability remains weak,
with CAPE values around 100 J/KG and shear near 25 knots.

Showers will increase ahead of the approaching cold front
Monday morning, with more widespread precipitation likely by
late morning as the cold front and upper-level jet move in. This
will further destabilize the atmosphere, bringing a 50% chance
for convective showers capable of producing lightning, graupel,
heavy rain below 4,500 feet, and gusty winds up to 35 mph.
Brief, heavy snow may occur with stronger showers above 4,500
feet, potentially leading to up to half an inch of snowfall. In
general, snow levels will range from 4,500 to 5,500 feet MSL,
with light snowfall expected in mountain valleys. Areas above
6,500 feet could receive up to 8 inches of new snow with the
frontal passage Monday.

By Monday evening, temperatures and snow levels will drop to
around 3,000 feet. With the upper-level trough lingering over
the area, showers will continue for much of Tuesday, bringing a
25% chance of a rain-snow mix in lower elevations below 3,000
feet at least through Tuesday morning. Surface temperatures are
likely (50% chance) to stay at or just above freezing in the
Treasure Valley, making snow accumulation unlikely.

LONG TERM...Wednesday through Sunday...Broad upper troughing
will be in place mid-week, and maintain below normal
temperatures across the entire region. However, significant
uncertainty exists in the potential evolution and progression of
a northern stream disturbance that may drift southward into
southern Idaho on Thursday, which would bring another round of
precipitation. The probability of precipitation on Thursday will
range from 20-30% in the lower elevations and 50-70% in the
mountains. Snow levels will briefly approach valley floors
during the morning hours, but any travel impacts are expected to
be limited. A drying trend will begin Friday as the influence
of an upper-level anticyclone increases through the weekend,
bringing an increase to slightly above-normal temperatures by
Sunday.

&&

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

&&

$$

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DISCUSSION...BW
AVIATION.....SP
HYDROLOGY....JDS/BW
SHORT TERM...JDS
LONG TERM....JR