118
FXUS65 KBOI 300056
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
656 PM MDT Wed Jul 29 2026

.UPDATE...Updated aviation discussion.

&&

.KEY MESSAGES...
- Isolated severe thunderstorms over south-central Idaho late
  this afternoon through early evening pose a threat for
  isolated strong outflow winds up to 60 mph.

- Smoke will limit high temperatures and continue degraded air
  quality through the end of the week.

- A dry cold frontal passage Saturday into Sunday will bring
  gusty winds and elevated fire weather concerns, with gusty
  conditions continuing into Sunday due to a tight surface
  pressure gradient.

&&

.SHORT TERM /Through Friday Night/...
Issued 221 PM MDT WED JUL 29 2026
An upper level ridge centered over the Intermountain West will
maintain hot and dry conditions across southeast Oregon and
southwest Idaho through Friday night. High temperatures will be
moderated due to the persistent smoke across much of the
forecast area but should still reach above normal for many
locations. Lower valley locations will range from the upper 90s
to 103, accompanied by low relative humidity values during the
peak heating hours.

Isolated severe thunderstorms are expected to develop late this
afternoon into early this evening across south-central Idaho,
particularly within southern Twin Falls County and the Western
Magic Valley. There is sufficient middle level moisture and
strong enough surface heating to yield elevated instability
across south-central Idaho. Inverted-V thermodynamic profiles on
forecast soundings highlight a favorable environment for
isolated strong outflow winds up to 60 mph which has been
outlined in SPC`s marginal risk today.

&&

.LONG TERM /Saturday through Wednesday/...
Issued 221 PM MDT WED JUL 29 2026
A pattern transition begins Saturday as an upper level trough
moves across the Pacific Northwest and pushes a dry cold front
through southeast Oregon and southwest Idaho Saturday afternoon
into Sunday morning. Minimal atmospheric moisture will limit
precipitation potential with this passage, keeping conditions
predominantly dry across the area.

The primary impact from this frontal passage will be strong and
gusty winds. West to northwest surface winds will increase to
20 to 30 mph with gusts up to 40 mph along and behind the front
Saturday afternoon and evening. Combined with low relative
humidity, these gusty winds will result in heightened fire
weather concerns across the region. This wind threat will
continue into Sunday across southwest Idaho with the tight
surface pressure gradient behind the exiting front.

Behind the front, daytime temperatures will drop 5 to 10 degrees
on Sunday and Monday, bringing high temperatures back down to
near seasonal normals. High pressure will begin to rebuild over
the Great Basin Tuesday into Wednesday, leading to lighter winds
and a gradual warming trend through mid-week.

&&

.AVIATION /00Z Thursday through Friday/...
Issued 656 PM MDT WED JUL 29 2026 Widespread wildfire smoke
reducing visibilities with areas of MVFR and IFR conditions.
Mountains obscured in smoke. Isolated thunderstorms SE of KTWF
and KJER until 30/03Z with gusty winds up to 45kt. Surface
winds: SW- NW 5-10 kt. Winds aloft at 10kft MSL: SW 5-15kt.

KBOI...MVFR visibility in smoke from wildfires. Surface winds:
variable less than 6 kt until 30/06Z, then SE 4-7kt.&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Air Quality Alert until 2 PM MDT Friday for IDZ011>015-028-029-
     033.
     Red Flag Warning until 9 PM MDT this evening for IDZ426.
     Air Quality Alert until 1 PM MDT Thursday for IDZ016-030.
OR...Air Quality Alert until 1 PM MDT /noon PDT/ Friday for
     ORZ062>064.
&&

$$

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AVIATION.....LC
SHORT TERM...JDS
LONG TERM....JDS