FXUS65 KBOI 250235
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
835 PM MDT Sat Aug 24 2024

.DISCUSSION...Showers have been most numerous this evening in
northern Malheur County/OR and the Weiser River Valley/ID, in
reasonable agreement with but slightly east of forecast. These
showers should taper off by midnight, but new showers should
move into south-central Idaho from Nevada overnight through
Sunday. Satellite loop supports these trends.  Another area of
showers should develop Sunday afternoon and early evening in
the Boise Mountains and eastern Valley County/ID, right over
the most active fires. No showers are expected in eastern Oregon
Sunday. Patchy fog is expected Sunday morning in the currently
rainy valleys in Idaho. Latest HRRR model has less smoke than
previous forecast in south-central ID Sunday.  No updates.

&&

.AVIATION...Mostly VFR with mid-level ceilings. MVFR/IFR and
mountain obscuration near wildfires. Scattered rain showers
decreasing by 25/05Z, except persisting for KTWF/KJER overnight.
Patchy mountain valley fog Sunday morning. Isolated showers/
thunderstorms over central Idaho mountains Sunday afternoon.
Surface winds: variable 5-10 kt, becoming W to NW 5-15 kt after
25/15Z. Winds aloft at 10kft MSL: variable 5-15 kt.

KBOI...VFR with scattered/broken mid level clouds. Surface winds:
light and variable overnight, then NW 7-12 kt with gusts to
15-20 kt after 25/16Z.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Monday night...Showers and any
thunderstorm development will organize across SE Oregon and far
SW Idaho this afternoon/evening along the upper trough axis. The
wetter air mass could support locally heavier rainfall from
showers and storms, but with cooler air mass and lighter winds
aloft, outflow potential looks to max out around 30 mph. Also,
the storm motion across SE Oregon could be relatively slow
adding to the heavier rainfall potential. The focus of
precipitation development will shift to s-central Idaho
overnight, following the track of a closed low at the base of
the trough. The low lifts into e-central ID on Sunday keeping a
chance of showers in the ID mountains through early evening.
Gusty outflow winds to 30 mph will again be possible from
thunderstorms. Elsewhere, dry and relatively cool conditions
are backed by a northwest wind. Monday is dry with warming
temperatures responding to a short wave upper ridge pushing in
from the coast.

As winds aloft weaken tonight and Sunday, wildfire smoke will
begin to fill in across mtn valleys in w-central Idaho.
Smoke will return to SW Idaho later Sunday as circulation
around the upper low wraps it to the south and west. While smoke
may initially stay in layers aloft on Sunday, would not be
surprised to it draining into the Snake Plain Monday morning as
has been the case in recent days.

LONG TERM...Tuesday through Saturday...Strengthening southwest
flow will warm temperatures back to around normal on Tuesday.
This is in advance of a sharp upper trough that will push
through the Pac NW Tuesday night and Wednesday. An accompanying
dry cold front will cross SE Oregon and SW Idaho Tuesday night,
bringing gusty northwest winds. Wednesday is about 10 degrees
cooler than Tuesday with northwest flow keeping breezy winds,
especially through the middle Snake Plain. An upper ridge
rebuilds over the region to end the week, keeping it dry and
warming temperatures to around 5 degrees above normal for Friday
and Saturday.

&&

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

&&

$$

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DISCUSSION...LC
AVIATION.....SH
SHORT TERM...DG
LONG TERM....DG