689
FXUS65 KBOI 190254
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
854 PM MDT Sat May 18 2024

.DISCUSSION...Another dry cold front will move across the area
late this evening, bringing brief gusts 30-40 mph with winds
remaining breezy overnight. Cooler air behind the front will
result in highs on Sunday 10-15 degrees cooler than today.
The winds will remain breezy into Sunday, strongest in the
Magic Valley where gusts to 40 mph may occur. Any significant
chance (20-50%) of showers will be limited to the northern
mountains of central Idaho and northeast Oregon, closer to the
core of the upper level trough. Weak instability will develop
Sunday afternoon in these areas, so a few strikes of lightning
will also be possible in stronger showers. Forecast remains on
track and no updates planned this evening.

&&

.AVIATION...VFR with some high clouds over the region. There is
a 20 to 50 percent chance of showers in far northern Baker
County and the West Central Idaho mountains on Sunday. Snow
levels 5000-6000 ft MSL. Surface winds: NW 5-15 kt increasing to
10-20 kt with gusts 25- 40 kt tonight with a cold front. Winds
aloft at 10k ft MSL: W 20-35 kt.

KBOI...VFR with high clouds tonight, becoming clear on Sunday.
Winds NW 5-10 kt increasing to 10-15 kt with gusts 20-30 kt
around Sun/05Z due to cold front. Winds diminishing early Sunday
morning, but gusts to 20 kt return Sunday afternoon.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Monday night... The successive
upper level lows to our north will continue to bring near
normal temperatures and breezy westerly winds to most of the
forecast area. A low chance of showers (30% chance or less)
exists for the West Central and Baker County, OR mountains late
this evening into Sunday morning from the passing front. Snow
levels will be right around 5000 feet overnight, jumping to
6000 feet during the day, so some late showers this evening
could bring some snow flurries to mountain valleys north of
a Cascade, ID-Baker City, OR line.

Cooler temperatures are anticipated for the region late Sunday
into Monday as a trough digs into the region, bringing a cooler
air mass over the Intermountain West. This air mass will most
likely be dry, but some models are showing weak showers over the
Central ID mountains on Monday morning. This low will then
slowly move east on Monday evening, but wraparound showers are
likely (40-50% chance) over higher terrain that evening. Current
hi-res model blends show weak thunderstorms forming near the
OR-NV order and over the Snake River Valley in ID, although
confidence is low with exact locations of convective
development.

LONG TERM...Tuesday through Saturday...An upper level trough
will move to the east on Tuesday, bringing dry and cool
northerly flow to the region as a weak ridge builds in by
Tuesday afternoon. This will bring a slight warming trend ahead
of a deep cut off low on Wednesday. There is substantial model
agreement in cooler temperatures and widespread precipitation at
some point on Wednesday-Thursday, but there`s still significant
variability in precipitation timing. Current forecasts show
around a tenth of an inch of QPF in the valleys, with up to
three quarters of an inch in the mountains by Thursday evening.
Snow accumulation is mostly isolated to above 6000 feet, with
around 1-3 inches expected by Thursday evening to those
elevations. A similar pattern to earlier in the week will
return on Friday, with dry upper level northwest flow ahead of
another potential system incoming on Saturday. Models currently
disagree much more on timing and positioning of that upper level
low.

&&

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

&&

$$

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DISCUSSION...ST
AVIATION.....BW
SHORT TERM...SA
LONG TERM....SA