Drewsey, Oregon Weather Forecast Discussion

467
FXUS65 KBOI 221546
AFDBOI
Area Forecast Discussion
National Weather Service Boise ID
946 AM MDT Mon Sep 22 2025
.DISCUSSION...A trough remains over eastern ID this morning with
northerly flow aloft. Wildfire smoke from central WA will move
into the area later today and is visible on satellite this
morning around Baker and northern Malheur County. Today will be
the coolest day of the next seven days. A ridge will build into
the region later today with a warming trend into Wednesday.
Winds at the surface are breezy northwest today, especially
through the Magic and Treasure Valleys before shifting to the
east-southeast on Tuesday and Wednesday. Breezy southeast winds
expected during the afternoons on Tuesday and Wednesday
through the I-84 corridor in Baker County, and the Treasure
Valley to the Magic Valley. Temperatures are near normal today
warming to 10 degrees above normal by Wednesday.
&&
.AVIATION...VFR. Smoke from fires in Washington moving over the
area, most dense over E/SE Oregon and west-central Idaho
mountains. Height of smoke layer generally around 10,000 feet.
KBKE has highest chances of near surface smoke. Surface winds:
SW-NW 5-15 kt. Winds aloft at 10kft MSL: NW to N 10-20 kt.
KBOI...VFR. Smoke aloft around 10,000 feet. Surface winds: W to
NW 7-12 kt. Gusts around 20 kt this afternoon.
&&
.PREV DISCUSSION...
SHORT TERM...Today through Wednesday night...At 1 AM MDT
satellite showed Sunday`s cold front well east of our CWA and
the last of the showers in the Boise Mountains about to exit
east also. After patchy valley fog this morning in Harney,
Baker, and Valley (ID) Counties, dry northwesterly flow aloft
will bring a sunny, breezy, and cool day followed by a clear,
calm, and cold night tonight. High pressure aloft will build
strongly over our area Tuesday and remain until Thursday, with
a warming trend under continued clear skies. An upper low in
Calif is now forecast to stay well south of previous forecasts
which had it moving across NV and UT by Wednesday. The new
track keeps it too far south to affect our weather. Back to
temperatures, Tuesday morning should be the coldest period
with lows 30 to 35 in the mountains and upper 30s through 40s
in the valleys, rising only slowly Wednesday and Thursday.
Highs will warm faster resulting in 50-degree diurnal ranges
in eastern OR Tuesday and Wednesday. Finally, smoke from
wildfires in central WA will spread into our CWA later today
through Tuesday, worst in Baker and northern Malheur Counties,
according to HRRR model. But we think HRRR is over-forecasting
the smoke in our CWA, carrying patchy smoke as far south as
the OR/NV border late tonight and Tuesday morning before
retreating northward again later Tuesday.
LONG TERM...Thursday through Monday...An upper level ridge over
the western U.S. is expected to flatten and shift east of the
forecast area on Thursday, as a series of troughs pass to the
north. Concurrently, a closed low along the CA coast will drift
inland and stall over SoCal/Nevada. This will place E Oregon and
SW Idaho into a disorganized transitional flow between these
three features, resulting in above normal temperatures, dry
conditions, and relatively light winds for Thursday. A shallow
trough to the north is anticipated to clip the area Thursday
night/Friday, lowering max temperatures approximately 5 degrees
and promoting breezy afternoon winds on Friday. Conditions
should remain dry with the bulk of the moisture favoring north.
Latest model guidance maintains near-zonal flow and slightly
above normal temperatures for E Oregon and SW Idaho over the
weekend and early next week. Cloud cover will increase by Sunday
as the mid-latitude storm track taps into subtropical moisture.
However, there are discrepancies with how sufficient the
moisture will be when it spreads across the forecast area. For
now, current forecast will keep a slight chance (10-20%) of
precipitation for Monday due to the lapse of certainty.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
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DISCUSSION...KA
AVIATION.....CH
SHORT TERM...LC
LONG TERM....SH

NWS BOI Office Area Forecast Discussion