Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 211010

Area Forecast Discussion
National Weather Service Boise ID
410 AM MDT Sat Oct 21 2017

.SHORT TERM...Today through Sunday...A deep moisture plume and
strong westerly flow will push a warm front across the interior NW
today. Precipitation starts as snow this morning across much of
southeast Oregon with snow levels around 4000 feet. The front and
accompanying rain/snow advances into southwest Idaho late this
morning, pushing into central Idaho by evening. Snow levels will
range from around 4500 feet over the central Idaho mountains to
5500 feet along the ID/NV border through this afternoon.
Mountains of east-central Oregon and west-central Idaho will see
steady precipitation continue into Sunday under moist westerly
flow. Drier conditions develop across southeast Oregon and areas
from the Snake Plain to the NV border on Sunday. Snow levels rise
overnight and into Sunday, ranging from 8000 feet across the
central Idaho mountains to 10000 feet along OR/NV and ID/NV
border by Sunday afternoon. Temperatures 10-15 degrees below
normal today will warm to within 5 degrees of normal on Sunday.

.LONG TERM...Sunday night through Friday...Showers will end across
the NE Oregon mountains and the west central Idaho mountains on
Monday morning as an upper level ridge begins to build into the
region and the moisture tap from the aforementioned system shuts
off. Temperatures will warm to slightly above normal values,
although northwest flow will keep temperatures at bay, compared to
SW Oregon. A trough will dig south along the Canadian Rockies into
Montana on Thursday, as a strong blocking ridge builds across the
Gulf of Alaska. A cold front will move through the region on
Thursday morning with showers focused across the higher terrain.
Forecast confidence remains low on the strength of the cold front
and temperature forecasts with this system. Northwest flow continues
into the extended period with dry conditions, as a blocking ridge
continues in the Gulf of Alaska.


.AVIATION...Precipitation becoming widespread around 12z in SE
Oregon and 18z in SW Idaho. Mountains obscured. Snow levels 3500-
4000ft this morning with snow near KBNO changing to rain by 18z as
snow levels rise to around 9000ft by 00z/Sun. Snow levels over
central ID mountains will be slowest to rise. Surface winds SW-SE 10-
20kt. Winds aloft at 10kft MSL: Westerly 25-35kt increasing to NW 35-
50kt by 00z/Sun, shifting to the WSW 35-50kt by 09z/Sun.

Sunday outlook...Generally VFR. Precipitation will continue over the
NE Oregon mountains and West central ID mountains with local MVFR on
Sunday with mountain obscuration and snow levels near 7500-9000ft.
Surface winds SW-SE 5-15kt.





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