804
FXUS65 KBOI 301553
AFDBOI
Area Forecast Discussion
National Weather Service Boise ID
953 AM MDT Wed Apr 30 2025
.DISCUSSION...Mostly clear skies are in place this morning,
with the exception of areas of low stratus in portions of the
Treasure Valley, Western Magic Valley, and Long Valley. These
clouds are expected to dissipate within the next couple of
hours. This afternoon, cumulus development and a few isolated
showers are possible over the Central Idaho Mountains on the
backside of the departing low. Breezy northwesterly winds will
keep temperatures near seasonal normals today, while skies
remain mostly clear. A warming and drying trend will continue
Thursday into Friday, with temperatures gradually climbing from
the mid-70s on Thursday to the low 80s by Friday in the
Treasure Valley. No forecast updates are needed at this time.
&&
.AVIATION...Patchy fog and low stratus to mix out by late
morning, bringing local IFR/LIFR conditions to KJER/KMYL through
18Z. Mountains obscured by low clouds. VFR conditions return
everywhere by early afternoon. Surface winds: NW 5-15 kt gusting
to 25 kt. Winds aloft at 10kft MSL: NW to NE 10-20 kt.
KBOI...Mostly VFR. Low stratus deck and fog lingring around the
foothills this morning. VFR conditions will prevail by early
afternoon. Surface winds: NW 4-6 kt in the morning, then NW 10
kt with gusts to 20 kt during the afternoon.
&&
.PREV DISCUSSION...
SHORT TERM...Today through Friday night...Rain showers have
ended across most of SW Idaho this morning as a weak, shortwave
trough exits toward the southeast. Precedent moisture, combined
with cooler and calmer conditions this morning, have created
mountain-valley fog development across portions of northeast
Oregon and w-central Idaho. Breezy winds will continue for the
Magic Valley and vicinity through mid-day today due to a
persisting surface pressure gradient. Behind the trough,
remnants of mid-level moisture and weak instability will help to
generate isolated afternoon showers in the central Idaho
terrain, but impact is expected to be minimal. Thereafter, a
high-amplitude ridge over the eastern Pacific today will move
inland by tonight, and center over the forecast area by late
Thursday. Strong subsidence from the ridge will bring dry and
sunny conditions, with temperatures warming to approximately 5
to 8 degrees above normal on Thursday. Further warming is
anticipated Friday as the ridge axis passes to the east of the
area and is replaced by prevalent southerly flow aloft.
LONG TERM...Saturday through Wednesday...A large Pacific trough
will approach late Friday night and transition to a cut-off low
over the weekend. The center of the low is projected to track
farther south than previous model runs, and is now expected to
move over southern CA/NV. Despite this evolution, rounds of
moisture are still forecast to spread into eastern Oregon and
southwestern Idaho throughout the weekend, and temperatures will
lower to near/slightly below normal. The highest probability of
showers and thunderstorms is on Saturday, with precipitation
chances reaching 50-80%. Saturday afternoon instability and
moisture parameters will be favorable for thunderstorm
development, with around a 20% chance of occurring across the
forecast area. Activity will decrease in southeast Oregon, but
continue in southwest Idaho, for Sunday and Monday as the center
of the low moves over Utah/Arizona. Models begin to differ
after Monday, but currently favor a drying and warming trend for
most areas Tue/Wed.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
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DISCUSSION...JDS
AVIATION.....SA
SHORT TERM...SH
LONG TERM....SH
