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Area forecast discussion 
National Weather Service Pendleton or
1129 am PST sun Dec 4 2016

Update...the latest radar was showing a plume of moisture that
drifted south into Oregon and snow levels had lowered in central
Oregon where rain and changed to snow in Bend. Elsewhere the snow
from earlier along the east slopes of the Washington Cascades had
diminished and the Winter Weather Advisory was cancelled. Meanwhile
an upslope flow persists in the blue and Wallowa Mountains where a
Winter Storm Warning and Winter Weather Advisory continues


Previous discussion... /issued 1100 am PST sun Dec 4 2016/

Update...the latest radar was showing pcpn striking the or/WA
Cascades and then lessening over the basin before the upslope flow
increases the pcpn along the Blue Mountains where ski bluewood
Washington reported five inches of snow. Elsewhere and along the
east slopes of the Washington Cascades three inches had fallen
around Roslyn and Cle Elum. Further south along the east slopes of
the Oregon Cascades temperatures remained above freezing but a cold
front is forecast to move through the region today which will lower
snow levels later this morning/midday. The bulk of the moisture will
slip south into the Oregon Cascades today while the upslope flow in
and near the Blue Mountains should persist with snow levels hovering
around 4000 feet.

Pcpn will persist today and a cold front will sweep across the
region. Pressure gradients should tighten creating windy conditions
in portions of the area and a Wind Advisory was hoisted over
the Kittitas Valley and over the lower Columbia Basin of Washington.

Elsewhere and across our far eastern zones a Snow Advisory remains
in effect for Wallowa County and so does a Winter Storm Warning for
the Blue Mountains where additional accumulations can be expected
and the present short term forecast appears on track for now.

Aviation...18z tafs...VFR conditions today due to improving
conditions behind a cold front that is moving southward across
central and NE Oregon today. Kbdn and krdm may have periods of MVFR
until 21z due to -sn reducing visibility to 3-5sm. Krdm and kbdn
will have cigs of broken-overcast 025 until 21z, when cigs improve to broken
035-040 and continuing through tonight. Otherwise, scattered-broken 050-080
through this afternoon at kpdt and kalw through tonight. Kykm,
kdls and kpsc will have bkn120 through this afternoon, then few-scattered
120-180 tonight.

Winds will increase late this morning and this afternoon as the
front moves through. West or northwest winds of 15 to 25 kts with
gusts up to 30 kts possible at times. Winds will gradually decrease
this evening after 05/03z. Polan

Previous discussion... /issued 340 am PST sun Dec 4 2016/

Short through Tuesday...a complex weather system will
move through the region today. Snow levels will rise some from
central Oregon to northeast Oregon this morning, then fall in the
afternoon as a cold front passes. Meanwhile snow levels of 2100 to
3000 feet over south-central Washington this morning will gradually
fall through the day behind the front. Precip amounts will be
decent, especially over the Blue Mountains, Wallowa County and
immediately near the Cascade crest. Thus will continue all current
winter weather advisories. May have to add a Winter Weather Advisory
for portions of the Oregon Cascade east slopes, but would like to
see how precip develops this morning. Locations below 2500 feet
should see mostly rain, with only a few snow flurries late this
afternoon or early this evening as precip ends in these areas. Winds
will be breezy to locally windy. Strongest winds still appear to be
over portions of the Kittitas Valley, and will continue the Wind
Advisory. Will see a wind down in showers overnight, then another
Pacific system will move into the region Monday morning. This system
will spread varying amounts of snow showers over the region through
Tuesday morning. These showers will wind down Tuesday afternoon.
Snow levels in the basin may rise enough to mix with or change to
rain Monday afternoon. Overall snow accumulations with this system
will be light, though will have to take a look at central Oregon in
later forecast packages as there is the possibility of upslope
enhanced snow in this area. 90

Long term...Tuesday night through Saturday. High pressure will
build offshore Tuesday night and move east across the area
Wednesday. A few snow showers may linger in the northeast mountains
Tuesday night, but dry conditions are expected Wednesday. Another
storm system will approach the coast Wednesday afternoon and light
snow may develop along the Cascades Wednesday evening before rapidly
spreading east early Thursday morning. Cold air remains in place and
light snow is likely Thursday. Significant snow accumulations are
probable. Another problem is possible overrunning of warmer air
Thursday afternoon and night. The exact timing and location of any
warmer air remains uncertain. Snow showers will persist Friday and
Saturday, especially in the mountains, as a series of disturbances
move across the area. Coonfield


Preliminary point temps/pops...
PDT 45 27 35 23 / 70 20 40 30
alw 48 31 36 28 / 80 30 40 30
psc 52 28 37 26 / 20 10 50 30
ykm 49 21 36 22 / 20 10 30 30
hri 49 27 37 25 / 30 10 40 30
eln 43 23 33 21 / 40 0 40 30
rdm 45 20 36 18 / 60 20 40 30
lgd 40 23 32 23 / 90 30 30 40
gcd 42 22 34 23 / 80 40 50 40
dls 50 33 39 29 / 70 10 40 30


PDT watches/warnings/advisories...
or...Winter Storm Warning until 10 PM PST this evening for orz502.

Winter Weather Advisory until 10 PM PST this evening for orz050.

Winter Weather Advisory until 3 PM PST this afternoon for orz509.

Washington...Winter Storm Warning until 10 PM PST this evening for waz030.

Wind Advisory until 6 PM PST this evening for waz026.




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