Harper, Oregon Weather Forecast Discussion

746
FXUS65 KBOI 161551
AFDBOI
Area Forecast Discussion
National Weather Service Boise ID
951 AM MDT Tue Sep 16 2025
.DISCUSSION...Starting off with some fog/stratus in sheltered
mtn valleys this morning, otherwise looking at clear skies
across the area. The fog/stratus will burn off by Noon as an
upper ridge keeps skies clear through the day. The morning
weather balloon from KBOI is showing 6-8 degrees of warming
aloft (5-10kft MSL) over the last 24h which will translate to
the surface today. This will raise high temperatures to near
normal. The current forecast is on track.
&&
.AVIATION...Local IFR in mtn valley fog/stratus through 18Z.
Otherwise VFR. Surface winds: E-S 5-15kt. Winds aloft at 10kft
MSL: Variable up to 10 kt.
KBOI...VFR with easterly surface winds.
&&
.PREV DISCUSSION...
SHORT TERM...Today through Thursday night... Clear skies and
light winds overnight tonight will allow for an environment
conducive for radiational cooling. This will allow lows tonight
to drop into to around the mid to upper 40s throughout the Snake
Plain, and even around freezing near Burns, the Camas Prairie,
and higher elevations in the West Central Mountains. Another
side effect of these clear skies and light winds will be the
development of patchy fog in lower laying areas, favoring
mountain valleys. Fog that develops should mix out after
sunrise. This will be the case again overnight Tuesday.
Aside from that, weather throughout the short-term is looking to
be quiet. The upper-level low that brought us our weekend
weather is currently east of our area centered over the ID/WY/MT
border; as this low continues to push eastward, ridging will
begin to build in across our area. This will allow for dry
conditions, but will carry with it a warming trend in our
daytime highs. Temperatures tomorrow are expected to be right
around normal, around 80 degrees in the Snake Plain and eastern
Oregon (mid-70s in mountain valleys and western Magic Valley).
By Thursday, temperatures will reach 5-10 degrees above normal,
around the mid to upper 80s throughout the Snake Plain and
eastern Oregon (around 80 degrees in mountain valleys).
LONG TERM...Friday through Tuesday... Come Friday afternoon, a
shortwave and remnant moisture from what is now Tropical Storm
Mario will make its way up the coast and into our area. While
uncertainty remains on how far north this moisture will make it,
mid to high level clouds will begin to increase through Friday.
There will also be a 10-20% chance of showers along and south of
the Nevada border Friday/Saturday afternoons. While the chance of
precipitation Sunday through early Tuesday remains under 15% area
wide, northwest flow aloft may allow for some shortwaves to
propagate across our area. This could allow for chances of
precipitation to increase in the days to come. By Tuesday
afternoon, guidance is generally in good agreement of an upper
level closed low moving northeast over our area from off the coast
of California. As a result, precipitation chances will increase
to 25 in eastern Oregon and 15% across southwest Idaho Tuesday
afternoon.
&&
.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
DISCUSSION...DG
AVIATION.....DG
SHORT TERM...NF
LONG TERM....NF

NWS BOI Office Area Forecast Discussion