231
FXUS65 KBOI 121524
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
924 AM MDT Wed Jun 12 2024

.DISCUSSION...Dry cold front passed through overnight with gusty
northwest winds that will continue through the afternoon in the
Snake Basin east of Boise. Tonight should be clear and cool with
calming winds then mostly sunny and hotter again Thursday under
a passing upper ridge. Latest models show enough moisture and
instability for a slight chance of thunderstorms in/near Twin
Falls County late Thursday and Thursday evening, already in the
current forecast. The deep, cold upper low in the Gulf of Alaska
is now forecast directly over our CWA Monday with much better
model consistency than yesterday. Our forecast has high temps in
the 60s to mid 70s Monday but latest models look at least 5
degrees colder and highs will be lowered in this afternoon`s
package. NBM is among the warmer models but even it shows
accumulating snow above 7000 feet in the central Idaho Mountains
Monday and Tuesday. All this happens in the extended period.
Current forecast is good in the short term so no updates for now.

&&

.AVIATION...VFR and mostly clear. Surface winds: W-NW 5-15 kt,
gusts 20-25 kt KBOI southeast through the Magic Valley terminals.
Winds aloft at 10kft MSL: W-SW 15-30 kt.

KBOI...VFR under clear skies. Surface winds: NW 7-13 kt. Gusts
up to 20 kt this afternoon.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Friday night...A dry cold front is
moving through the CWA this morning, with gusts to 40 mph
reported at KONO in the past few hours. This front was moving
east through the Treasure Valley as of 2 AM MDT, and will move
through the western Magic Valley between 9 AM and noon. Gusts to
30 mph will continue generally east of Mountain Home this
afternoon into early this evening. Slightly cooler air will
filter in behind the front, and highs today will be 5-10 degrees
cooler than yesterday, but still 5-10 degrees above normal. As
our upper flow turns more southwesterly tonight, in advance of a
large and strong upper level low off the Canadian coast, we
will see warmer air once again drawn northeast over the region.
Highs Thursday will be about 5 degrees warmer than today. In
addition, meso models are now indicating that sufficient
moisture and instability will work into the SE corner of the CWA
(roughly meaning eastern Owyhee County and the western Magic
Valley) late Thursday afternoon and into the overnight hours,
leading to an increase in the area of showers and thunderstorms
forecast there. This moisture will move out by early Friday, and
there is no chance of precipitation in the forecast for Friday
or Friday night. Temps will cool back down around 5 degrees
Friday compared to Thursday, and another cold front Friday night
will lead to even cooler temperatures heading into the long term
period.

LONG TERM...Saturday through Wednesday...Models have finally
come into reasonable agreement on the upper level flow over the
weekend. After the front Friday night, and the passage of an
associated upper level shortwave trough, much cooler air will
move into the area Saturday. There will also be a slight chance
of showers in the far northern higher terrain Saturday afternoon
and evening. High temperatures Saturday may actually be a
degree or two below normal. Breezy northwest winds will develop
Saturday, and continue to a lesser extent Sunday and Monday. As
heights continue to fall Saturday into Sunday, temps will
continue to cool. The main part of the upper level system
(initially to our northwest) will move through as a closed low
Sunday night into Monday. The latest GFS has this system move
directly over the CWA, but ensembles place a higher probability
on passage centered just to our north. The difference is
important, because the more southern track would both cool us
off more and bring more precipitation than indicated in this
new forecast. For now, we have a roughly 15% to 35% chance of
showers and thunderstorms over the north, mainly in the higher
terrain, Sunday night through Tuesday night. Temperatures will
cool to 5 to 10 degrees below normal Sunday through Tuesday,
then moderate to near normal Wednesday. Should the GFS track
prove to be accurate, temps would be 10-20 degrees below normal
Sunday through Tuesday, with precipitation spreading to all
parts of the CWA.

&&

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

&&

$$

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