902
FXUS65 KBOI 150243
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
843 PM MDT Fri Jun 14 2024

.DISCUSSION...Today was 5-10 degrees cooler than yesterday behind
last night`s weak cold front. A stronger cold front over eastern
Oregon late today will move across Idaho zones later tonight with
increasing west/northwest winds and a 15 to 30 percent chance
of showers and thunderstorms. Saturday will be about 15 degrees
cooler than today along with significantly stronger west winds
than today, especially in the Snake Basin and Camas Prairie.
These changes are due to a deep upper low approaching from the
Gulf of Alaska. Further cooling will occur Sunday and especially
Monday when the upper low center passes right over our CWA.
Showers will increase in northern and central areas with snow as
low as 5500 feet MSL. Southern areas will have less chance of
showers (15-30 percent chance) but will also be breezy and about
20 degrees cooler than normal for mid-June. Current forecast is
on track with all this and supported by most models.

&&

.AVIATION...VFR with mid and high level clouds. A chance of showers
and thunderstorms through Sat/08Z. Surface winds: W-NW 5-15 kt with
gusts to 30 kt. Winds aloft at 10kft MSL: W 10-20 kt, becoming SW
15-25 kt by 15/12Z.

KBOI...VFR. Low confidence (around 10 percent chance) of
showers/thunderstorms between Sat/00Z and Sat/06Z. Surface winds:
W to NW 8-12 kt overnight, then NW 14-22 with gusts to 28 kt after
15/14Z.

Sunday Outlook...VFR. Mid and high clouds with a 15-30 percent
chance of rain/snow showers in SE Oregon and w-central Idaho
mountains Sunday night. Snow levels falling to 5500-6500 ft MSL
when precipitation chances increase. Surface winds on W-NW 5-15
kt with afternoon gusts to 15-25 kt.


&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Sunday night...A deep upper level
low will move into the Pacific Northwest today, with a weak cold
front moving through the region this evening and another stronger
front moving through tomorrow morning. A low chance (20-30%
chance) of showers and thunderstorms with this initial frontal
passage will develop through the region in a line from Rome, OR
to McCall, ID late this afternoon into the evening. Current
soundings show dry lower level conditions, with high based
thunderstorms/virga showers as this front moves through.
Localized strong outflow winds anywhere from 40-50 mph are
possible with these showers.

As successive fronts move through the region, breezy westerly
winds 10-20 mph with gusts to 30 mph will accompany each frontal
passage. High ridgetops will see gusts to 40 mph. In addition
to these frontal winds, a strong gradient wind will develop
today and tomorrow as the upper low center moves into the
Pacific northwest, tightening the pressure gradient aloft.

Temperatures will plummet from about 5 degrees above normal
today to 10-15 degrees below normal tomorrow with the incoming
cold air mass. The anomalously low pressure system will continue
to bring below normal temperatures through the rest of the
short term period, but Sunday looks relatively dry except for
some high terrain showers in Baker/Valley County.

LONG TERM...Monday through Friday...The unsettled pattern will
continue into the long term period, with another upper level
low pressure system developing over the Pacific Northwest on
Monday. There is current model disagreement on where the low
center will go, therefore, there is quite a bit of uncertainty
in the amount and extent of precipitation for our region.
The best chance of precipitation with the highest model
agreement is in high terrain in southwest Idaho. Temperatures
will remain below normal, with a chance of snow above about 6000
feet Monday night into Tuesday morning. There is about a 10%
chance of snow accumulation in McCall, ID on Tuesday morning.
After Tuesday, the unsettled conditions look to move east, as a
ridge starts to build into the region. There is still model
discrepancy on the development of this ridge, but the cluster
and ensemble solutions favor the development of a ridge. This
outcome will bring dry conditions and above normal temperatures
for most of the region starting Wednesday through the end of the
long term period.

&&

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

&&

$$

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