Crystal, Idaho Weather Forecast Discussion

037
FXUS65 KBOI 201601
AFDBOI
Area Forecast Discussion
National Weather Service Boise ID
1001 AM MDT Sat Sep 20 2025
.DISCUSSION...A ridge remains over the area today with warm
temperatures continuing. Mid level moisture from a system in
northern CA will bring isolated thunderstorms to the area,
mainly along the NV border in OR and south of the Snake Plain
in ID. Gusty outflow winds up to 50 mph possible in the vicinity
of storms. A trough from the Gulf of Alaska will bring a cold
front to the area on Sunday, which will interact with the
moisture already in place. Scattered showers and isolated
thunderstorms form early Sunday morning ahead of the front, and
intensify with the daytime heating on Sunday afternoon as the
front moves east. The front will bring breezy west-northwest
winds during the afternoon Sunday. Then warm and dry conditions
for the remainder of the week. No updates.
&&
.AVIATION...VFR and scattered high clouds. Isolated to scattered
showers and thunderstorms along the ID/NV border and in SE/E
Oregon this afternoon/evening, with potential impacts to
KTWF/KJER. Precipitation will move slowly NE over time. Main
impact would be brief rainfall and gusty winds up to 45 kts with
the strongest storms. Surface winds: variable up to 10 kt.
Winds aloft at 10kft MSL: variable 5-10 kt.
KBOI...VFR with increasing high clouds. Surface winds SE 5-10
kts, this afternoon becoming NW 5-10 kt, becoming SSE after
sunset.
Sunday Outlook...Generally VFR with a cold frontal passage
expected Sunday afternoon. Showers and thunderstorms are
expected along the front, with the highest chances for
precipitation north of the Snake Plain in the higher terrain of
NE Oregon and central Idaho. MVFR will be possible in the
strongest storms along with gusty frontal winds. Surface winds
less than 10 kt increasing to WNW 10-20 kt.
&&
.PREV DISCUSSION...
SHORT TERM...Today through Monday night...Mid-level moisture
in northern NV and CA will shift northward into our CWA today
for a 15 to 30 percent chance of thunderstorms south of the
Snake Basin, i.e., or more than yesterday. A cold front from
the Gulf of Alaska will come in Sunday and develop more showers
and thunderstorms from moisture in place over our CWA. Greatest
chance of pcpn (60 to 80 percent) will occur in the Boise
Mountains and eastern half of Valley County, ID. Showers and
storms will also develop in the southern Sawtooths, and those
storms may have stronger outflow winds (up to 50 mph) than the
northern storms. The front will also bring 10 to 15 degrees
cooling and shift winds to west/northwest 15 to 20 mph with
gusts to 30 mph. Clearing west to east Sunday night, then mostly
sunny, breezy, and cool Monday. Clear and calming Monday night
with lows Tuesday morning in the upper 20s through 30s in the
mountains and generally 40s in the valleys.
LONG TERM...Tuesday through Saturday...High pressure is expected
to return to the region Tuesday through Thursday, with a gradual
warming trend each day. Temperatures will hover around 5 degrees
above normal. Uncertainty enters the forecast Friday into Saturday,
with around 60% of ensemble guidance suggesting a breakdown of the
ridge and Pacific trough impacting the area. Blended model guidance
suggests a slow drop in temperatures during this timeframe, with
continued dry conditions. Close to 40% of ensemble guidance suggest
eastern Oregon and southwest Idaho will see shower activity Friday
into Saturday, so anyone with outdoor plans should monitor the
situation closely. The most aggressive guidance suggests a 20-30%
chance of precipitation Friday Night into Saturday.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
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DISCUSSION...KA
AVIATION.....CH
SHORT TERM...LC
LONG TERM....MC

NWS BOI Office Area Forecast Discussion