675
FXUS65 KBOI 201625
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1025 AM MDT Thu Jun 20 2024

.DISCUSSION...A weak shortwave will move across the area today,
bringing increased clouds this afternoon. This will keep a
threat of showers and thunderstorms, mainly over northeast
Oregon over the Blue Mountains, north of Baker City and McCall
in Idaho, and a slight chance of showers and thunderstorms in
southern Twin Falls County and areas east. Drier air will move
in from the west, but there will be enough moisture for showers
and thunderstorms to form over the central ID mountains and
southern Twin Falls County on Friday afternoon. Then the flow
aloft shifts to the southwest, bringing warmer conditions.
There is a 40-60 percent chance of temperatures in the lowest
valleys exceeding 100 degrees on Saturday, and 50-70 percent
chance of exceeding 100 degrees on Sunday. Forecast on track
with no updates.

&&

.AVIATION...VFR. Surface winds: E-SE 5-15 kt. Winds aloft at
10kft MSL: S-SE 10-15 kt.

KBOI...VFR. Surface winds SE 5-10kt, switching to NW 5-10kt
after 18z/Thu.

Weekend Outlook...VFR with clear skies. Hot temperatures will
bring high density altitudes Saturday and Sunday. Surface winds
W-SW 10-20kt during the afternoons, light during the night.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Saturday night...A weak upper-level
trough remains over the forecast area today, maintaining warm
and dry conditions. Expect mostly clear skies, though smoke from
a wildfire in southwest Owyhee County may cause hazy conditions
this afternoon across southwest Idaho. Temperatures in the
lower valleys will reach the low 90s today. A weak trough will
pass through tonight into Friday, limiting the warming on Friday
to 2-4 degrees above Thursdays high temperatures. High-
resolution models indicate enough moisture for cumulus cloud
development along the Idaho/Nevada border.

A Pacific system will reach the British Columbia coast on
Saturday, forming a ridge and creating a southwesterly flow
aloft over the forecast area. This could bring the warmest
temperatures of the year so far, with a 40-50% chance of the
Treasure Valley seeing maximum temperatures reach 100 degrees or
higher on Saturday. Historically, Boise`s first 100-degree day
typically occurs around July 7th, though in 5 of the last 11
years, it has happened in June.

LONG TERM...Sunday through Thursday...Hot temperatures will
persist on Sunday, with highs forecasted to reach around 100
degrees in the Treasure Valley. The Pacific system from the Gulf
of Alaska will move across British Columbia on Sunday, bringing
a surface cold front toward the forecast area from the
northwest. This front, along with cooler temperatures, will not
reach the area until Monday, providing a brief respite from the
heat. Temperatures will drop into the mid-90s on Monday.
However, hot and dry weather will continue through Wednesday. A
much stronger Gulf of Alaska trough is expected to move inland
starting Thursday, initiating a cooling trend. Ensembles show
good agreement on this shift occurring late next week.

&&

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

&&

$$

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DISCUSSION...KA
AVIATION.....KA
SHORT TERM...JDS
LONG TERM....JDS