702
FXUS65 KBOI 131027
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
427 AM MDT Sat Jul 13 2024

.SHORT TERM...Today through Monday night...Hot and smoky today
as the region remains on the edge of a hot upper high. Clouds
and virga showers have crept into SE Oregon this morning
revealing the leading edge of deeper monsoon moisture lifting
out of the Great Basin. Isolated to scattered high-based showers
and thunderstorms will develop by late afternoon over SE Oregon
and south of the Snake Plain in Idaho. Given the hot/dry near
surface layer, dry thunderstorms and gusty winds to 50 mph will
be the main threat through this evening. Some high resolution
models are showing nocturnal activity, and with elevated
instability decided to keep a mention of thunderstorms in
forecast for tonight, though confidence is low. Showers and
storms fire up again Sunday as heat/moisture/instability get
added support from a weak trough pushing in from the coast.
Similar to Saturday, focus of development will be over SE Oregon
(mostly Harney and Malheur Counties) and far SW Idaho. Can`t
rule out showers/storms pushing into the Snake Plain each
evening though probabilities remain low (10-15%). The increase
in cloud cover will take the edge off of afternoon highs on
Sunday, though overnight lows will be warm tonight and Sunday
night. Monday will see temperatures drop a few more degrees as
the hot upper high shifts eastward. It`s looking like most
lower elevation sites will see a break to the streak of 100
degree highs on Monday before another stretch starts on Tuesday.
Mtns of SW Idaho will see a slight chance (~20%) of showers and
thunderstorms, otherwise it remains dry.

.LONG TERM...Tuesday through Saturday...The upper high will
build back into southern UT through the period with the ridge
axis amplifying along the Continental Divide. The return of the
ridge will bring the potential for dangerously hot conditions
starting Wednesday. While long range models show the air mass
supporting temperatures in lower valleys above 103 and mtn
valleys passing 90, we`ll likely still be dealing with wildfire
smoke which could impact temperatures. Monsoon moisture will
build under the high center before being transported into the
region on southerly flow by the end of the week. Though not
being picked up by the NBM, deterministic models show signs of
afternoon mtn showers/storms starting as early as Thursday and
continuing through Saturday.

&&

.AVIATION...Wildfire smoke causing low VFR and local MVFR to IFR
visibility from e-central Oregon into the w-central Idaho
mountains. Isolated to scattered high-based showers and
thunderstorms will develop across SE Oregon and along the ID/NV
border after 21Z. Gusty outflow winds to 45 kt are possible
near showers/storms. High density altitude due to very hot
daytime temperatures. Surface winds: NW-SW 5-15kt. Winds aloft
at 10kft MSL: W-SW 10-25 kt.

KBOI...VFR, smoke layers aloft. About a 20% chance smoke lowers
visibilities below 6 miles at the airport between 10z and 15z.
High density altitude due to very hot daytime temperatures.
Light winds.

Sunday Outlook...Reduced visibility due to wildfire smoke. High
density altitudes due to hot temperatures. Isolated to scattered
high-based showers and thunderstorms in the afternoon could
bring strong outflow winds. Storms could impact lower valleys.
Surface winds W-SW 10-20kt during the afternoons.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Fire Weather Watch from Sunday afternoon through Sunday
     evening IDZ400>402-420-423-424-426.
     Excessive Heat Warning until midnight MDT Sunday night IDZ012.
     Red Flag Warning from noon today to 9 PM MDT this evening
     IDZ423-426.
     Excessive Heat Warning until midnight MDT tonight IDZ014-033.
     Heat Advisory until midnight MDT tonight IDZ015-016-029-030.
     Heat Advisory from midnight tonight to midnight MDT Sunday
     night IDZ033.
OR...Fire Weather Watch from Sunday afternoon through Sunday
     evening ORZ636-637.
     Excessive Heat Warning until midnight MDT Sunday night ORZ064.
     Red Flag Warning from noon MDT /11 AM PDT/ today to 9 PM MDT
     /8 PM PDT/ this evening ORZ636-637.
     Excessive Heat Warning until midnight MDT /11 PM PDT/ tonight
     ORZ062-063.
     Heat Advisory until 11 PM PDT this evening ORZ061.
     Heat Advisory from midnight MDT /11 PM PDT/ tonight to
     midnight MDT /11 PM PDT/ Sunday night ORZ062-063.
     Fire Weather Watch from 11 AM PDT this morning through Sunday
     evening ORZ646.

&&

$$

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SHORT TERM...DG
LONG TERM....DG
AVIATION.....DG