An upper wave and a strong upper level jet drove into the Pacific Northwest producing heavy snow in the mountains of West Central Idaho.
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The episode as NWS BOI wrote it up.
An upper wave and a strong upper level jet drove into the Pacific Northwest producing heavy snow in the mountains of West Central Idaho.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Boise, ID wrote its last area forecast discussion before the first event at Dec 27, 9:55 AM MST, 5 minutes earlier.
Area Forecast Discussion
National Weather Service Boise ID
955 AM MST Tue Dec 27 2016
.DISCUSSION...Upper wave and strong upper level jet are driving
into the Pacific Northwest this morning. Dry conditions at the
lowest levels delayed the start of snow in the Snake Plain from
Boise south and east, but points north and west have been snowing
since early this morning. The snow will taper off in the valleys
from west to east through the remainder of this morning, while
strong mid and upper level winds will support snowfall in the
east-central Oregon and west-central Idaho mountains through the
day. However snowfall intensity will wane as leading upper wave
moves east of the area. Have updated forecast for this afternoon
to lower chance of snow in Snake Plain and southeast Oregon and
decrease snow amounts in the mountains with the expected decrease
in intensity. A weak feature upstream (coming onshore over WA this
morning) could deliver another brief round of snow showers to the
valley, while intensifying snowfall in the mountains early this
evening, otherwise snow will be ending or tapering off to showers
by 06Z tonight.
&&
.AVIATION...Mountains obscured. Widespread MVFR, areas of IFR,
and local LIFR conditions in snow will spread east to the KTWF/KJER
area by 18z. There is a slight chance of light freezing rain in the
Snake River Valley 00z-06z. Expect gradually improving conditions
after 06z, and mainly VFR conditions after 12z Wednesday. Surface
winds southeast to southwest 10-20 kts becoming southwest to west 10-
20kts after 06z. Winds aloft at 10k ft msl west 30-40 kts.
&&
.PREV DISCUSSION...
SHORT TERM...Today through Wednesday...A moist west-northwest
flow aloft was directed at the Pacific Northwest this morning. The
leading edge of the snow reached SE Oregon, with light snow
reported at Baker City and Burns. The snow will spread into SW
Idaho through this morning. The bulk of the snow will occur in the
northern mountains due to orographic effects (upslope) from the
stronger mid-level winds. Gusty southeast winds in the Baker
Valley was likely resulting in blowing/drifting snow. The snow
will continue mainly in the mountains through tonight. A drier
northwest flow will follow on Wednesday as an upper ridge builds
along the west coast.
A Winter Weather Advisory for snow and blowing snow will remain
in effect today for Baker County. A Winter Weather Advisory for
snow will remain in effect for the northern mtn zones of SW Idaho,
which includes the Upper Weiser, Boise Mountains, West Central
Mountains, and Camas Prairie through tonight. Blowing snow is not
expected to be an issue in the lower elevations, although gusty
winds to 30 mph are expected in the mountains above 6000 feet. For
the Treasure Valley, most of the snow is expected this morning,
with amounts of up to an inch in the Upper Treasure Valley
(including Boise) and 1-2 inches in the Lower Treasure Valley.
Additional light accumulations are possible this afternoon and
evening. Total amounts of up to an inch are expected in the
Western Magic Valley, except 1-2 inches north of Jerome. There is
also a slight chance for freezing rain tonight in the Treasure
Valley near the base of the Owyhees, although precip amounts in
this area will be light.
LONG TERM...Wednesday night through Tuesday...Broad upper ridge
will bring drier wx with warming at higher elevations Thursday.
Valleys will stay cold resulting in temporary inversion
conditions. Cold front and upper trough from the north will bring
snow showers Friday afternoon and evening. Little if any cooling
expected behind the front as flow aloft quickly becomes westerly
Saturday ahead of another...much stronger...cold front and upper
trough moving south through BC. Snow or snow showers will expand
over the entire nwrn US Sunday through Tuesday as the trough
presses south. After that there is the growing possibility of an
arctic surge. Models are coming into better agreement on strong
northerly flow aloft into our area and the potential for extremely
cold wx after next Tuesday.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Winter Weather Advisory until 5 AM MST Wednesday
IDZ011-013-028-033.
OR...Winter Weather Advisory until 4 PM PST this afternoon ORZ062.
&&
www.weather.gov/Boise
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DISCUSSION...DG
AVIATION.....JT
PREV SHORT TERM...BW
PREV LONG TERM....LCThe national radar mosaic for the moment the first event began.
1 heavy snow. Local standard time, as filed.
The COOP observer at Cambridge measured 8 inches of new snow and reports of 11 inches were received around the Council area.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2016Every state in 2016This day in weather historyWarnings in Idaho, December 2016
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 672297.