Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 172131

Area Forecast Discussion
National Weather Service Boise ID
231 PM MST Wed Jan 17 2018

.SHORT TERM...Tonight through Friday...An upper ridge will shift
east tonight, followed by increasing southwest flow aloft on
Thursday. Precipitation along and ahead of a cold front will
spread into southeast Oregon and central Idaho on Thursday. Warmer
air ahead of the front will lead to high snow levels, ranging
from 7000 to 8500 feet. The front will continue to push through
the area Thursday night, accompanied by widespread precipitation
and falling snow levels. Additional light snow accumulations are
likely overnight, mainly above 4500 feet. An upper trough will
follow the cold front on Friday. Snow levels will lower to near
valley floors, with a chance of rain and snow showers in the lower
valleys and snow showers (with light accumulations) in the higher
elevations. Breezy to locally windy conditions will develop
through Thursday afternoon as the front approaches, with the
strongest winds expected in the mountains and near the OR/NV
border. Winds are not expected to be strong with the frontal
passage. Record and near record temperatures are forecast for
Thursday. Temperatures will be much cooler on Friday (near or
slightly above normal).

.LONG TERM...Friday night through Wednesday...The long term
forecast continues to be very active. The exiting trough Friday
night is followed closely by another trough early Saturday
morning. Snow levels sit right around valley floors at the
beginning of the period. QPF amounts on Saturday are not very
impressive with little to no accumulations in the lower valleys.
So even with the snow levels down to the valley floors, snow
accumulations for the valley on Saturday will be little to none.
There will be a brief break in the precipitation Sunday morning
before the next trough pushes in. Lower valleys are likely to see
this system begin as snow then changeover to a wintry mix or
straight rain. This pattern will continue through Tuesday evening
with each new trough bringing chances of snow to lower valleys,
but quickly transitioning to a wintry mix then rain. Snow levels
creep up above 3500 feet MSL by late Wednesday which will turn any
precipitation in the lower valleys to rain. Temperatures hover
right around seasonal norms.


.AVIATION...VFR. Patchy fog in and around KONO, KEUL, and KMYL
for Thursday morning. Showers begin pressing into SE Oregon after
15z and continue to press eastward through the day. Surface winds,
SE through the Treasure Valley 10-15 kts, southerly elsewhere
5-15 kts. Winds aloft to 10k feet MSL, southwest 10-30 kts through
00z then 30-50 kts.





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