Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 240946

Area Forecast Discussion
National Weather Service Boise ID
346 AM MDT Fri May 24 2024

.SHORT TERM...Today through Sunday night...An upper level trough
will move into our forecast area today as an upper level ridge
moves east. Temperatures will be around 10 degrees warmer than
yesterday in response to the departing ridge. A cold front
associated with the trough will move into eastern Oregon this
afternoon and into southwest Idaho by mid to late this evening.
Weak instability in place as the front moves through will
support showers and isolated thunderstorms. The core of the
upper level trough will move across our northern areas,
resulting in the highest chance of precipitation (60-90%) in
these areas. Elsewhere, a 20-50% chance of showers will develop.
Snow levels will be high today, generally around 8000 feet MSL.
Gusty winds may accompany the frontal passage and near
thunderstorms with brief gusts to 40 mph possible. The trough
will slowly move east into Saturday, keeping chances of showers
going mainly across the mountains and eastern areas. Snow levels
will drop to 5500-7000 feet, allowing for minor snow
accumulations on high peaks. A 5-10 degree temperature drop is
anticipated on Saturday behind the front. Breezy winds will
develop as the trough exits our area, with gusts generally 20-35
mph, except up to 40 mph in the Magic Valley. Dry conditions
and lighter winds will return Sunday as an upper level ridge
builds overhead. A warming trend will begin that will continue
into the extended period.

.LONG TERM...Monday through Friday...Sunny skies and above
normal high temperatures should prevail throughout most of the
region as a relatively dry but progressive flow pattern
dominates. Dry, stable ridging will start the period off on
Monday but quickly transition into a series of back-to-back low
pressure system migrations beginning Tuesday. The majority of
their associated moisture and instability will stay well to the
north of the region with a brushing by affect occurring across
the northern sections the forecast area. This effect, in turn,
will set up low probabilistic (15 - 35%) chances for showery
activity in those sections from Tuesday afternoon through
Thursday. The possibility for afternoon thunderstorms will be
enough to mention the slight chance for occurrence Tuesday
afternoon supported by the initial trough passage. With the
flow pattern initially taking on a southwestly trajectory, this
will draw up a few pockets of moisture into the Twin Falls area
providing the ingredients for afternoon thunderstorms across
the mountains on Tuesday afternoon. Periods of breezy wind
conditions are expected across the Steens, Trout Creek, and
Owyhee Mountain Ranges as pressure gradient tightenings occur
with each trough system transition. High temperatures are
expected to range from the high 70`s through the mid 80`s -
cooler during the trough passages.


.AVIATION...Mainly VFR. Patchy mountain valley fog this
morning, including near KMYL. Scattered showers and isolated
thunderstorms developing in eastern OR this afternoon along a
cold front, moving across SW Idaho this evening. Mountains
obscured in showers with brief MVFR/IFR conditions in storms.
Snow level around 8kft MSL. Surface winds: E-SE 5-10kt, becoming
NW 10-20kt with gusts to 35kt along and behind the front. Gusty
and erratic winds near thunderstorms. Winds aloft at 10kft MSL:
W-SW 10-20 kt.

KBOI...VFR. SE 5-10 kt, shifting to NW 5-15 around 02-05Z/Sat,
with brief gusts to 30 kt along a cold front. Scattered light
rain showers developing this evening.

Weekend Outlook...Mainly VFR. Lingering showers on Saturday,
mainly in the mountains. MVFR/IFR possible in precip, along
with mountain obscuration. VFR and dry Sunday. Snow levels
generally 5500-7500 ft MSL. Surface winds W-NW 10-20 kt with
gusts 20-35 kt Saturday. Sunday winds W-NW 5-15 kt. Winds
strongest in the Magic Valley.





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