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000
FXUS65 KBOI 140301
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
901 PM MDT Sat Apr 13 2024

.DISCUSSION...Upper level trough continues to spin off the CA
coast with favorable conditions for thunderstorm development
over central OR this evening. A few strong storms formed west of
Burns but that is about it this evening. The trough is forecast
to split into two separate shortwaves by Sunday afternoon, with
one piece over southern CA and the other over northern NV. The
northern NV portion will bring in dry air from the southeast on
Sunday over most of our forecast area with showers and
thunderstorms focused over the Blue Mountains in OR and with
some showers and storms possible over the central ID mountains.
The dry slot will keep most of southwest ID dry on Sunday as the
northern shortwave weakens and consolidates back into the
parent trough on Monday morning. Current forecast on track with
no updates.

&&

.AVIATION...Scattered showers and isolated thunderstorms across SE
Oregon near KBNO will taper off overnight. Isolated to scattered
showers and thunderstorms will develop Sunday mainly across SE
Oregon and the mountains of SW Idaho. Mountain obscuration with MVFR
to IFR conditions in showers and storms. Surface winds: SW-SE 5-15
kt, increasing to 10-20 kt on Sunday, with gusts to 30 kt across far
southern ID. Snow levels lowering to 6000-7500 ft MSL. Winds aloft
at 10kft MSL: SE-E 15-30 kt.

KBOI...VFR and mostly clear. Increasing mid-level clouds Sunday
afternoon. Southeast surface winds 10-20 kt overnight, becoming
south Sunday afternoon.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Monday night...Some weak
thunderstorm activity has begun over central Oregon as of 2pm
MDT. A stray shower or two has been observed over Western Harney
County, OR, as the low pressure system continues to move in to
Northern California. High resolution models continue to keep
most thunderstorm activity to our west through the evening, with
a chance of a strong thunderstorm or two for Western Harney
County and southern Baker County as the low continues inland.
Strong wind is the most likely hazard, due to widespread dry
and abnormally warm surface air.

The low then looks to move to the southeast, keeping most of
the shower and thunderstorm activity to our south. High terrain
will see the best chance (40-50% chance) for showers,
thunderstorms, and cooler temperatures tomorrow, especially over
southeast Oregon and areas north of the Boise Mountains-
Treasure Valley. A stray shower can`t be ruled out for the
Treasure Valley, although confidence is low (10% chance). Cool
temperatures from the low will lower snow levels to around
6000-7000 feet over the region tomorrow evening, with minimal
snow accumulations expected for high terrain over ~6000 feet,
mainly near the Nevada border.

Temperatures look to be very warm today, with highs reaching the
low 80s across the Treasure Valley due to clear skies and breezy
southeast winds. As the low moves in, temperatures will drop to
the upper 60s tomorrow, accompanied by breezy westerly winds.
These westerly winds will increase to impactful levels on Monday
afternoon as upper level northwesterly flow takes over and the
pressure gradient tightens when the low moves east, mainly in
the Magic Valley and Upper Treasure Valley. Gusts around 40-50
mph and sustained winds around 20-30 mph are anticipated for
these regions.

LONG TERM...Tuesday through Saturday...A large upper level trough
that expands from southern Canada into the northern Rockies will be
the main driver of our weather through the early periods. The
models/ensembles remain in decent agreement with regard to the
southern extent of the moisture for a 15 to 30 percent chance of
showers in central Idaho Tuesday and Wednesday while showing dry
conditions in SE Oregon and the remainder of SW Idaho. Models also
agree that winds will be breezy to locally windy during those days,
especially in s-central Idaho. Ensemble members depict a large
spread (15-20 degrees) in temperatures through Thursday, with the
bulk of the members supporting a cooler solution. Temperatures trend
from slightly below normal on Tuesday to a few degrees above normal
by Thursday. Models are in better agreement with regard to a weak
high pressure ridge arriving by the end of the week. This would
continue the dry conditions, along with lighter winds and warmer
temperatures.

&&

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

&&

$$

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