Granite, Oregon Weather Forecast Discussion

633
FXUS65 KBOI 150257
AFDBOI
Area Forecast Discussion
National Weather Service Boise ID
857 PM MDT Sun Sep 14 2025
.DISCUSSION...Cold front has moved through the area this
evening and the shower and thunderstorm threat is winding down
with the loss of daytime heating. Patchy fog will form overnight
as the system moves northeastward. Showers will linger over the
west central ID mountains on Monday afternoon. An upper level
ridge builds into the area on Tuesday with a warming trend. No
updates to the forecast.
&&
.AVIATION...Isolated showers continuing in w-central ID
overnight and brief MVFR/IFR. Mtns obscured in precip and low
clouds. Patchy mountain-valley fog and low stratus early Monday
morning. Otherwise, VFR. Surface winds: generally W-N 5-15 kt.
Winds aloft at 10kft MSL: W to NW 10- 25 kt.
KBOI...VFR, becoming mostly clear Monday morning. Surface winds: NW
5-10 kt.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Tuesday night...Showers and
thunderstorms are ongoing across Eastern Oregon crossing east
into SW Idaho, and in the west-central Idaho mountains. They are
occurring due to a pronounced, negatively tilted, shortwave
trough, and associated cold front, making its way across the
northwestern U.S. states. Thunderstorms will track N/NE/E
(depending on vicinity to the center of the low) this afternoon
and evening. Threats for thunderstorms include gusty
outflow winds up to 50 mph, small hail, and heavy rainfall. A
cluster of storms in SW ID are existing in a maxima of vertical
wind shear (30+ kts of effective bulk shear), favorable
thermodynamics (MUCAPE > 500 J/kg), and above 75th percentile
PWAT values. They will need to be closely monitored as they
pass closely to the Upper Treasure Valley, where many of the
CAMs that have them persist for the next few hours. Much of the
thunderstorm threat will diminish after 6 pm MDT, however, an
isolated shower or thunderstorm can not be ruled out along our
northern counties (Baker, Adams, and Valley counties) overnight.
Fog potential Sunday night and early Monday morning is high in lower-
lying areas and mountain valleys with rainfall around the area.
The 500 mb low pressure system will slowly meander E/SE from
Northern Idaho later today and Monday. This will keep precipitation
chances mentionable for the west-central Idaho mountains during
daylight hours Monday. Late Monday into Tuesday, an upper-level
ridge will begin to build in, bringing temperatures back around
normal.
LONG TERM...Wednesday through Sunday...An upper-level ridge will
continue to build in Wednesday. Clear skies and slightly above
normal high temperatures (~5 degrees) can be expected. Over Thursday
and Friday, the ridge axis will shift more and more east, eventually
giving way to south/southwesterly flow aloft. This pattern is
accredited to an upper-level trough and low-pressure system off the
coast of California. As a result of this pattern, PoPs will slowly
increase Friday afternoon to mentionable amounts again, increasing
further Saturday and Sunday as well. Long range models disagree on
how Sunday progresses, thus, will hold off on any discussion that
far out.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
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DISCUSSION...KA
AVIATION.....SH
SHORT TERM...CH
LONG TERM....CH

NWS BOI Office Area Forecast Discussion