800
FXUS65 KBOI 081622
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1022 AM MDT Mon Jul 8 2024

.DISCUSSION...Upper level ridge continues to slowly move inland
over the western US. This will bring increased temperatures over
the next several days, with record high temperatures possible
from Tuesday through Thursday. Boise will likely see several
days of 103+ from Tuesday through Saturday. The record number
of consecutive days of 103+ is 4 days, which has happened 8
times since 1875! Monsoonal moisture begins to move northward
into southwest Idaho after Wednesday, and generally expands over
the whole area by next weekend. This will bring a threat of
thunderstorms which is not depicted very well in the models.
Cloudiness and smoke may also limit temperatures over the
weekend. No updates to the forecast.

&&

.AVIATION...VFR and mostly clear. Haziness, especially aloft, is
possible as wildfire smoke drifts into the area. High density
altitude due to very hot daytime temperatures. Surface winds: light
and variable, then NW 5-15 kt with gusts to 20 kt in the Snake River
Valley and on ridgetops this afternoon. Winds aloft at 10kft MSL: NW
5-15 kt.

KBOI...VFR and clear. Haziness aloft and likely distant as patchy
smoke blows to the southwest and northeast of KBOI. High density
altitude due to very hot daytime temperatures. Winds SE around 5-7
kt through the morning, shifting to NW 5-15 kt with gusts to 20 kt
by the afternoon.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Wednesday night...The high pressure
system will continue to move inland this morning, with record
high temperatures likely again across much of the West.
Temperatures were slightly cooler than forecast yesterday,
mainly due to the northerly flow, but satellite imagery at 3AM
MDT shows the ridge axis creeping inland and northerly flow now
over Eastern Idaho. Temperatures will reach the triple digits
in most valley locations today as the ridge moves into our
region, beginning a streak of triple digits through the work
week. The hottest day still looks to be Wednesday, with some
variation in models on the extent of the high temperature.
Current model probabilities show about a 30% chance of the
Treasure Valley exceeding 110F. Higher elevations will stay
relatively cool, with most locations reaching 90F with daytime
highs. Luckily, overnight lows still look to be in the upper 50s
to low 60s and 70s for most of the region, a welcome respite
from the extreme daytime temperatures. Have kept the products
and timing the same, with the exception of adding the Owyhee
Mountains to a heat advisory on Wednesday and Thursday due to
their rising overnight low and daytime high temperatures
compared to previous forecasts.

LONG TERM...Thursday through Monday... The heat wave will
continue through the work week, with Thursday and Friday still
showing many valleys with daytime highs above 100F. The high
pressure will then move east, with a push of monsoonal moisture
likely due to direct southerly flow. This will bring low chances
(<10% chance) of showers and thunderstorms, but confidence in
extent and location is still low. By late Sunday, a weak
shortwave trough looks to enter Northern California, bringing
cooler temperatures for the following week. Deterministic models
and cluster ensembles show relatively good agreement in slight
cooling by late Sunday into Monday. Excessive Heat Watches are
in effect from Friday to Saturday for most of the region except
higher elevations due to the continued risk for extreme heat
through the beginning of the weekend.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Excessive Heat Warning from 11 AM Tuesday to midnight MDT
     Thursday night IDZ012-014-033.
     Excessive Heat Watch from late Thursday night through Sunday
     evening IDZ012-014>016-030-033.
     Heat Advisory from noon Wednesday to midnight MDT Thursday
     night IDZ015-016-029-030.
OR...Excessive Heat Warning from 11 AM MDT /10 AM PDT/ Tuesday to
     midnight MDT /11 PM PDT/ Thursday night ORZ063.
     Excessive Heat Watch from late Thursday night through Sunday
     evening ORZ061>064.
     Heat Advisory from 10 AM Tuesday to 11 PM PDT Thursday ORZ061.
     Excessive Heat Warning from 10 AM Tuesday to 11 PM PDT
     Wednesday ORZ062.
     Excessive Heat Warning from 2 PM this afternoon to midnight
     MDT Thursday night ORZ064.

&&

$$

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DISCUSSION...KA
AVIATION.....JM
SHORT TERM...SA
LONG TERM....SA