525
FXUS65 KBOI 201536
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
936 AM MDT Sat Jul 20 2024

.DISCUSSION...Continued smoky and very hot with upper level ridge
extending from the Great Basin northward through the Intermountain
region and into Alberta. High confidence that heat will continue
through next Thursday, but there is growing confidence in a
cooling trend beginning Friday. Pacific short wave trough currently
forecast to move northward along the NW coast Sunday will set off
scattered thunderstorms in eastern Oregon Sunday afternoon,
maximizing Sunday evening. Current forecast already has this
but PoPs may be increased in the afternoon package. On Monday
thunderstorms will be mainly near the Nevada border and along
the eastern edges of Valley and Elmore Counties in Idaho.
Current forecast is on track.

&&

.AVIATION...MVFR or low VFR in smoke. Local IFR northwest of
KONO. High density altitude from heat. Isolated afternoon
thunderstorms near the NV border and in the central ID
mountains. 30-40 kt outflow winds from thunderstorms. Surface
winds: NW- NE 5-15 kt. Gusts 15-25 kt near KBKE KONO this
evening. Winds aloft at 10kft MSL: variable 5-15 kt.

KBOI...MVFR or low VFR visibility due to smoke. High density
altitude from heat. Surface winds: Light/variable until noon,
then NW 8-10 kt until sunset, then S-SE 5-10 kt overnight.

Sunday Outlook...MVFR or low VFR to local IFR from smoke. High
density altitude from heat. Scattered thunderstorms Sunday
in southeast OR, especially in Harney County, with 35-45 kt
erratic outflow winds. Surface winds: E-SE 5-15 kt.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Monday night...Upper level ridge
will continue to expand over the area today, with a few degrees
of warming compared to Friday. Record high temperatures over
the short term in some locations, depending on how thick the
smoke is. Wildfire smoke continues to impact the area, limiting
temperatures a few degrees below previous forecasts. We used
bias corrected temperatures over the past 10 days to account for
wildfire smoke in the temperature forecasts in the short term.
The hot conditions will support unstable conditions, with
isolated thunderstorms over central ID mountains and along ID/NV
border this afternoon. A shortwave off the CA coast will
support increased chances of thunderstorms on Sunday afternoon,
especially across eastern OR as the system moves north along the
WA/OR coast. A slight chance of thunderstorms continues into
Monday afternoon as this system slowly tracks northeastward.
Thunderstorm threats will mainly be erratic outflow wind gusts
up to 50 mph and lightning. Excessive heat warnings, and heat
advisories, remain in effect.

LONG TERM...Tuesday through Saturday...The upper level ridge
will continue through at least Thursday with continued hot
conditions. The ridge will also have substantial moisture in it
with precipitable water values in the 70-80th percentile for
this time of year. This will keep a threat of thunderstorms each
afternoon through Thursday, mainly over the higher terrain. A
trough over southwest Canada will bring cooler temperatures by
next Friday and Saturday, with temperatures cooling to near
normal or a few degrees below.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Excessive Heat Warning until 9 PM MDT Wednesday IDZ012-014-033.
     Heat Advisory until 9 PM MDT Wednesday IDZ015-016-029-030.
OR...Excessive Heat Warning until 9 PM MDT /8 PM PDT/ Wednesday
     ORZ063-064.
     Heat Advisory until 8 PM PDT Wednesday ORZ061-062.
     Red Flag Warning from noon MDT /11 AM PDT/ Sunday to midnight
     MDT /11 PM PDT/ Sunday night ORZ636-637.

&&

$$

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DISCUSSION...LC
AVIATION.....LC
SHORT TERM...KA
LONG TERM....KA