063
FXUS65 KBOI 170907
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
307 AM MDT Fri May 17 2024

.SHORT TERM...Today through Sunday night...The pattern
transitions to an upper-level trough over western Canada
beginning today, which will persist through the short term.

The first shortwave will move across the northern Rocky
Mountains later today, preceded by a cold frontal passage later
this morning. The associated cold front will sweep southeast
across southeast Oregon by 7 AM MDT and southwest Idaho between
sunrise and 11 AM. Wind speeds will increase behind the front
and will continue through the evening, with the strongest winds
expected from Mountain Home through the Western Magic Valley,
Camas Prairie, and Southern Twin Falls County. Wind gusts up to
50 MPH are possible, as indicated by the current Wind Advisory
in this area. Although moisture is limited with the frontal
passage, there is a 20% chance of showers along the frontal
boundary over the higher terrain of the West Central Mountains
of Idaho this morning. Temperatures today will be about 5
degrees below normal, with valleys reaching the upper 60s, which
is approximately 15-18 degrees cooler than yesterday
(Thursdays) highs.

A cold west-northwesterly flow will persist through Saturday as
the area remains between shortwaves, allowing temperatures to
reach normal. The next shortwave will move across the area from
Saturday evening into Sunday, bringing another cold front. This
system is stronger and colder than the previous one, causing
temperatures to drop about 10 degrees below normal and bringing
gusty westerly winds, especially in the Western Snake River
Plain. Additionally, there is about a 30% chance of showers
across the West Central and Boise Mountains of Idaho, with light
snow possible above 6000 feet.

.LONG TERM...Monday through Friday...Cool, unstable, and breezy
northerly flow will develop over the forecast area on Monday as
a trough passes through the Intermountain West. A 20-40% chance
of showers will persist over the southwest Idaho mountains
through Monday evening, though temperatures should rebound a few
degrees from Sunday`s high temps. A brief, weak ridge will
follow early Tuesday before the next trough arrives Tuesday
night into Wednesday. Shower chances will increase over E Oregon
and SW Idaho Wednesday, especially over the Idaho terrain,
along with a slight chance (15%) of afternoon mountain
thunderstorms as instability increases. Snow levels are forecast
to lower to 5000-6000 ft MSL by late Wednesday. Models begin to
vary significantly on the path and evolution of this trough,
and subsequent troughs, for the remainder of the week. However,
the overall pattern should maintain an active period across the
region, along with more days of below normal temperatures.

&&

.AVIATION...VFR. Isolated showers along a cold front in northeast OR
and w-central ID, decreasing by Fri/18Z. Local visibility reduction
from smoke near prescribed fires, mainly over the southwest Idaho
mountains. Surface winds: SW to NW 5-15 kt, becoming W to NW 15-25
kt with gusts to 25-40 kt by late this morning/aftn. Winds aloft at
10kft MSL: W to NW 25-40 kt.

KBOI...VFR. Hazy skies due to the prescribed fires in the Boise
Mountains. Surface winds: W-NW 5-10 kt, becoming NW 15-20 kt with
gusts 25-30 kt around Fri/15Z. Winds will decrease to 5-10 kt after
sunset, then variable up to 6 kt by Sat/06Z.

Weekend Outlook...VFR. Chance (20-50%) of showers in the central ID
mountains on Sunday. Snow levels 4500-5500 ft MSL. Surface winds
mainly SW to NW 10-20 kt with gusts to 25-35 kt for Sat/Sun.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Wind Advisory from 9 AM this morning to 9 PM MDT this evening
     IDZ014-016-028-030.
OR...None.

&&

$$

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SHORT TERM...JDS
LONG TERM....SH
AVIATION.....SH