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fxus65 kboi 230210 

Area forecast discussion
National Weather Service Boise Idaho
810 PM MDT sun Oct 22 2017

Discussion...showers have markedly decreased since sunset,
matching the forecast. Clouds will thin overnight, allowing fog to
form in Mountain-Valley, much of the lower Treasure valley, and a
large portion of Harney County. No changes to the forecast are
planned at this time.


Aviation...VFR. Isolated MVFR conditions with rain showers this
evening. Showers will diminish by midnight tonight. Patchy valley
fog will develop Monday morning. Best chance for fog will be at
kbno, kbke and keul. Surface winds southwest to northwest 10-20 kts
this evening will decrease to 5-10 kts by 06z. Winds aloft at 10k ft
mean sea level northwest 35-50 kts.


Previous discussion...
short term...tonight through Tuesday...frontal zone has weakened,
and any remaining pcpn will be light and confined to the higher
central Idaho mountains this evening. No pcpn after that. Clouds
will slowly decrease tonight and Monday and skies will be clear
Monday night and Tuesday except for patchy fog. With clouds around
tonight will be relatively mild with lows in the 30s in the
mountains to near 40 in the valleys. Monday night will be colder
due to clear skies and better radiational cooling. Lows Monday
night will be in the 20s in the mountains and 30 to 35 in the
valleys. High temps Monday and Tuesday will be slightly above
normal for late october: upper 40s and 50s in the mountains and
upper 50s to mid 60s in the valleys. Light winds through Tuesday.

Long term...Tuesday night through Sunday...the upper level ridge
over the intermountain region tonight will give way to northwest
flow aloft on Wednesday as the ridge relocates to off the West
Coast. This will allow an upper level trough from the Gulf of
Alaska to slide southeast over the northern rockies Wednesday
night. Most precipitation with this system will be north and east
of our County Warning Area. Models agree well on timing, but still differ on
amplitude of the trough and coverage of precipitation. Baker
County, Oregon, and the west central Idaho and Boise Mountains
will be on the periphery of the precipitation, which is expected
to be light in those areas. Cooler air and breezy northwest winds
will follow the system late Wednesday night and Thursday. Thursday
night and Friday the ridge will edge eastward, residing over the
intermountain region through the weekend. Temperatures will be a
few degrees above normal Thursday through Sunday.


Boi watches/warnings/advisories...




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