FXUS65 KBOI 270914
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
314 AM MDT Sat Jul 27 2024

.SHORT TERM...Today through Monday night...Smoky conditions and
poor air quality will persist throughout the day due to
unchanged surface winds. Similar to yesterday, this will help
keep temperatures a few degrees cooler, with the lower valley
reaching the upper 80s to low 90s. Moisture will increase this
morning as an approaching upper-level low, currently over
central California at 3 AM MDT, tracks north- northeast and
weakens while moving across the forecast area this evening.
There is ample residual monsoonal moisture, with precipitable
water values around the 60th percentile today. However,
instability will be limited by significant wildfire smoke. High-
resolution models indicate development primarily over the higher
terrain this afternoon. Better instability, dynamic support,
and moisture are expected further east across south-central
Idaho into the central Idaho Mountains, where a few storm
clusters may develop. The confidence for thunderstorms today is
low (20% chance), as most high-resolution models likely aren’t
accounting for smoke, which affects CAPE and temperature
forecasts.

Sunday is expected to be dry with light northerly surface winds
under a persistent weak westerly flow aloft. The HRRR model
shows some improvement in smoke aloft with increased westerly
flow; however, this seems unlikely due to the significant number
of large fires in Central Oregon. Increased wind may promote
slightly better afternoon mixing, but the northerly surface flow
is expected to continue bringing smoke from eastern Oregon into
the valleys.

Southwesterly flow returns on Monday ahead of the next Pacific
trough, but this will not significantly clear the smoke, as
smoke from the Park Fire in California will return aloft. The
trough and front are expected to reach eastern Oregon late
Monday. The main question is whether there will be enough
Pacific moisture for thunderstorms to develop late Monday night.
Most recent guidance favors a dry frontal passage, differing
from earlier forecasts. For now, a 15% chance of thunderstorms
is forecast for Monday night in parts of Southeast Oregon.

.LONG TERM...Tuesday through Saturday...A Pacific Northwest
trough is expected to bring a cold front through E Oregon and SW
Idaho early Tuesday morning. While moisture will be limited, a
slight chance (10- 20%) of showers and thunderstorms is forecast
along and behind the front for eastern OR and w-central ID
Tuesday morning and afternoon. Temperatures will cool a few
degrees Tuesday in the wake of the front, and afternoon west and
northwest surface winds will become breezy. The trough will
quickly exit by Tuesday night, and a strong ridge will
strengthen over the Intermountain West. Dry conditions with
warming temperatures will return by Wednesday, with temperatures
pushing past 100 degrees in the low elevations on Thursday.
Heat will intensify Friday/Saturday with south to southwest flow
dominating aloft. Widespread smoke is expected to continue from
regional wildfires, with degraded air quality likely.

&&

.AVIATION...Widespread low VFR/MVFR, and local IFR from smoke.
SCT/BKN high clouds. A 20% of showers/thunderstorms near the NV
border and in central Idaho later this morning and afternoon.
Presence of smoke could limit storm development. Surface winds:
variable less than 10 kt becoming W to NW 5-15 kt after Sat/18Z.
Gusts to 30-40 kt near thunderstorms. Winds aloft at 10kft MSL: W-SW
5-15 kt.

KBOI...Low VFR/MVFR from smoke. SCT/BKN high clouds. A 10% chance of
shower/t-storm activity reaching KBOI Sat/22Z to Sun/03Z. Winds S to
SE 4-8 kt this morning, then W to NW 5-15 kt around Sat/17Z.

Sunday Outlook...Low VFR/MVFR and local IFR conditions from smoke.
Winds generally W to NW 5-15 kt.

&&

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

&&

$$

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SHORT TERM...JDS
LONG TERM....SH
AVIATION.....SH