Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 221654
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
954 AM MST Sun Jan 22 2017

.DISCUSSION...Snow has begun to fall in SE Oregon and along the
ID/NV border in the southwest flow of an upper low off the PACNW
coast. Precip is expected to spread through the rest of the CWA
this afternoon. Snow levels will be around 4000 ft along the ID/NV
border and decrease to the north to around 3000 ft this afternoon,
so much of the Snake River Valley is forecasted to experience a
rain/snow mix, with the rest of the CWA being snow. Surface front
is currently in Central Oregon and will move through the area
later today, and will bring a brief break in precip tonight before
a shortwave brings snowfall for Monday. The current forecast
looks on track, and no updates are needed at this time. The Winter
Weather Advisory for Northern Malheur and Harney counties and
Baker county are still in effect.

&&

.AVIATION...A broad area of IFR in snow across southeast Oregon this
morning will shift into the mountains of southwest Idaho by
afternoon. In the Snake Plain will see low VFR or MVFR develop in
rain or a rain/snow mix from KEUL eastward to KTWF/KJER. Will see
IFR in snow in the vicinity of KONO. Surface winds remain gusty
today out of the east at 10-20 kts and gusts up to 35 kts. Southerly
winds aloft of 30-50 kts through 10k feet MSL.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Monday...Impressive upper low off the
WA/OR coast will remain nearly stationary today. Precipitation
along a front associated with the low will drive inland and reach
SE Oregon this morning and SW Idaho this afternoon. Snow will move
into Harney County early this morning and Baker/Malheur Counties
by mid-morning. There is enough snow to warrant a Winter Weather
Advisory across Baker County and far northern Harney/Malheur
Counties where generally 2-4 inches are expected. In addition to
the snow, gusty southeast winds of 15-25 mph will promote areas of
blowing and drifting across far northern Malheur County and Baker
County. Snow levels will be around 3000 feet in the Treasure
Valley where there will be a mix of rain and snow this afternoon
with little or no snow accumulation. The higher elevations of SW
Idaho are expected to receive 2-5 inches. Winds will also increase
later this morning, becoming breezy to locally windy in the
Treasure/Western Magic Valleys. The frontal system and
accompanying precipitation will exit to the northeast this evening
resulting in diminishing winds and precipitation. The upper low
off the WA/OR coast will move S-SE off the Washington coast
tonight through Monday. A shortwave will peel away from the low
and is expected to form a closed low in our general vicinity,
although the models still show significant differences. Went with
a blend of the GFS and ECMWF, with the dry NAM remaining the
outlier. The result is for light snowfall mainly near the Nevada
border tonight, shifting to the north on Monday for light
accumulations across most of SE Oregon and SW Idaho.

LONG TERM...Monday night through Saturday...A chance of snow
showers will remain over the forecast area Monday night as a broad
upper level trough moves over the Pacific Northwest. The trough
will shift east of the forecast area Tuesday with lingering
showers over the mountains of southwest Idaho Tuesday and Tuesday
night. As the trough continues to shift east a northerly flow will
develop over Idaho on the backside of the trough and ahead of a
developing ridge of high pressure just off the west coast. Can
expect mostly dry conditions over the forecast area Wednesday, but
models hinting that a weak system will be moving through the
northerly flow for a slight chance of snow showers over the
Central Mountains of Idaho. Wednesday night ridge of high pressure
will continue to build over the region, but models hinting at a
weak weather system trying to break through the upper level ridge.
Even though conditions will remain dry Wednesday night, a few of
the forecast models are hinting at a slight chance of
precipitation over southeast Oregon as this weak system moves
through the ridge. Will keep the forecast on the dry side for
Wednesday night and continue to monitor later model runs. Dry
conditions over the forecast area Thursday through Saturday as the
upper level ridge continues to build over the Pacific Northwest.
Temperatures through the extended period will remain below normal
with temperatures cooling through the week due to the northerly
flow that will be developing over the region. High temperatures
through the extended will be 10-15 degrees below normal.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...Winter Weather Advisory until 5 PM MST /4 PM PST/ this afternoon
     ORZ061>063.

&&

$$

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DISCUSSION...EP
AVIATION.....DG
PREV SHORT TERM...BW
PREV LONG TERM....JA



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