Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 300925

Area Forecast Discussion
National Weather Service Boise ID
325 AM MDT Fri Jul 30 2021

.SHORT TERM...Today through Sunday night...An area of high
pressure aloft will start to shift northward today, but will
dominate through the afternoon for continued hot temperatures.
Highs will once again be around 100F in the lower valleys.
Meanwhile, monsoonal moisture to our south will creep northward
during the afternoon with showers and afternoon thunderstorms
developing, mainly across southern Idaho and far southeast Oregon.
Some of the thunderstorms will produce gusty outflow winds and
brief heavy rain. The moisture will increase on Saturday with the
potential for heavy rainfall-producing thunderstorms leading to
the threat of flash flooding. The main threat areas will be on
steep terrain and near burn scars. An upper disturbance will
moving northward through the area and enhance the threat of
thunderstorms, including during the overnight hours of Saturday
night. The threat of thunderstorms with heavy rainfall will
continue Sunday through Sunday night. Another upper disturbance
will once again enhance the threat of widespread convection as it
moves through late Sunday through Sunday night. A Flash Flood
Watch is in effect Saturday afternoon through Monday for all
zones, except the Treasure Valley and Western Magic Valley. Below-
normal temperatures are expected through the weekend, but it will
also be humid.

.LONG TERM...Monday through Friday...Monsoon moisture will remain
over the region on Monday, keeping a threat of thunderstorms,
along with the threat of heavy rain. Temperatures will be around
10 degrees below normal with very high humidity for this time of
year. Then moisture values drop on Tuesday. There is still enough
residual moisture for afternoon showers and thunderstorms over the
mountains each day through Thursday before drier air moves into
the area. Temperatures will gradually warm to around normal by the
end of the period.


.AVIATION...Mostly VFR with areas of MVFR and terrain obscuration
due to wildfire smoke. Showers/thunderstorms generally south of
the Snake River Plain Friday afternoon and becoming widespread by
Friday evening. Surface winds: generally E-SE 5-15 kt except gusts
up to 40kt in vicinity of storms. Winds aloft at 10k feet MSL:
E-SE 10-20 kts.

Weekend Outlook...Numerous showers and thunderstorms expected
Friday through Sunday with areas of heavy rain, gusty thunderstorm
outflow winds, MVFR/IFR conditions, and mountain obscuration.


ID...Flash Flood Watch from Saturday afternoon through Monday
     afternoon IDZ011-013-015-028>030-033.
OR...Flash Flood Watch from Saturday afternoon through Monday
     afternoon ORZ061>063.



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