511
FXUS65 KBOI 130241
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
841 PM MDT Wed Jun 12 2024

.DISCUSSION...Another warm and dry evening across the forecast
area. Satellite imagery indicates at least one active fire
which is about 30 miles southeast of Jordan Valley, Oregon.
Southwesterly winds aloft are carrying the smoke plume northeast
towards Mountain Home this evening, resulting in hazy
conditions across Owyhee County and parts of the Upper Treasure
Valley. An upper- level ridge will strengthen late tonight
through Thursday, particularly across southwest Idaho, in
response to an approaching upper-level low anticipated to affect
the region this weekend. This will lead to another day of
above-normal temperatures with stable conditions. Smoke will
likely be trapped in the southwestern valleys of Owyhee County,
south of the Owyhee Mountains, overnight but shouldn`t affect
the Western Snake Plain. The forecast will be updated to account
for hazy conditions tonight into Thursday across Owyhee County.

The latest models show better agreement in bringing the low
center over the forecast area by Monday. If this trend
continues, the probability of precipitation will increase above
the current forecast precipitation chances across most of the
forecast area. This will be further addressed in the next
forecast package on Thursday morning.

&&

.AVIATION...VFR and mostly clear except for smoke mainly south
of KBOI and KMUO this evening. Surface winds: W-NW 5-15 kt
becoming variable 10 kt or less late tonight. Winds aloft at
10kft MSL: W-SW 15-25 kt.

KBOI...VFR under mostly clear skies. Smoke layers aloft, south
of KBOI, should dissipate after sunset. Surface winds: NW 7-13
kt, decreasing later this evening and becoming variable 6 kt or
less by 06Z/Thu.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Friday night...Little change from
previous forecast. Hotter Thursday as an upper ridge moves in
from the west. Significant cooling beginning Friday as a deep
upper trough in the Gulf of Alaska moves onto the northwest
coast. Friday looks 6-10 degrees cooler than Thursday, and
Friday night 6-10 degrees cooler than Thursday night (and
even cooler after that). Models show limited moisture but
enough instability for a slight chance of thunderstorms in
Twin Falls County late Thursday/Thursday evening. Light winds
tonight and most of Thursday, then westerly 20 to 30 mph in
Harney County/OR Thursday afternoon and evening, and in
southern Idaho Friday afternoon behind a surface cold front.


LONG TERM...Saturday through Wednesday...An active pattern
will develop over the extended period, offering a break from
summer heat and a brief return to more springlike conditions.
The core of an upper level trough will move by to our north
Saturday into early Sunday, bringing a dry cold front with much
cooler temperatures and breezy winds. Any chance (10-20%) for
showers will be limited to the northern mountains. Highs on
Saturday will be 10-15 degrees cooler than Friday with another
5 degrees cooling on Sunday. This will place lower valley highs
in the upper 60s to near 70 on Sunday, which is 10-15 degrees
below normal. Models continue to show a closed low moving
through the Pacific Northwest and Northern Rockies Sunday
through Tuesday. The exact track of this low will have a major
impact on our weather, with a more southerly track bringing the
potential for widespread rain (and high-elevation snow above
7000 feet MSL in the central Idaho mountains) and temperatures
15-25 degrees below normal. This southerly track is depicted
by roughly half of the EC ensemble members but is much less
prominent amongst the GFS ensemble. A more northerly track would
limit chances of showers and thunderstorms to the northern
mountains, but still bring continued cool temperatures and
breezy winds. By late Tuesday and Wednesday, models project the
upper level trough to lose amplitude and temperatures to rise
closer to normal, with drier conditions and decreasing winds
also expected.

&&

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

&&

$$

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DISCUSSION...JDS
AVIATION.....JDS
SHORT TERM...LC
LONG TERM....ST