Heavy Snow in Washington, February 3 to 5, 2019

Area Forecast Discussion
National Weather Service Pendleton OR
306 AM PST Sun Feb 3 2019

.SHORT TERM...Today through Tuesday. Weakening upper low moving
inland across California and Nevada spreading clouds and light
precipitation across much of the forecast area. This will continue
through the morning. Areas of fog over much of the Columbia basin
and valleys through the morning with rain and low clouds.
Meanwhile an upper low is moving southward from British Columbia
off the Pacific northwest coast late today and tonight.
Precipitation from this system will start to increase later this
afternoon. Temperatures will be fairly mild again today with highs
in the 40s. The upper low moving south along the coast will drag
a strong cold front through the region overnight into Monday
morning. The lower elevations should see a change over from rain
to snow by morning. The low continues to move slowly south along
the Oregon coast Mon then inland into northern California Tuesday.
Models indicate several short waves rotating through the low.
With a very cold airmass over the area expect periods of snow Mon
into Tue. Accumulations through the period will be fairly
significant especially over Oregon. The Columbia basin will also
have accumulating snow with the highest amounts along the Blue
mountain foothills with a northerly low level upslope flow.
Temperatures will be much colder with highs only in the teens and
20s.  94

.LONG TERM...Tuesday night through Sunday...Snow will largely have
ended by Tuesday night and with clearing skies for Wednesday and
Thursday morning expect some of the coldest morning lows of the year
in areas with fresh snow pack. Have guided temperatures toward the
bottom quartile of model guidance, mostly teens and single digits
for morning lows on both days. Suspect this will probably not be
quite low enough, but don't want to venture too much further under
consensus until we see what actually ends up on the ground
Monday/Tuesday. The next system drops south along the British
Columbia coast Thursday afternoon into early Friday morning with
broad troughing lingering over the region through the weekend. While
the moisture does not look especially impressive, occasional snow
showers through Sunday may add up to another inch or two for the
lower elevations with higher amounts in the Oregon Cascades and Blue
Mountains. Peck

&&

.AVIATION...12Z TAFs....Precipitation associated with the occlusion
of a filling upper low over the Snake River Valley will primarily
impact PDT/ALW/PSC today before tapering off this afternoon with a
snowflake or two possible mixing in with rain as it trails off.
Increasing westerly winds should yield improving ceilings at
PDT/ALW/PSC by this afternoon. The first of many bands of snow
develops late in the afternoon, but looks to stay away from the TAF
sites primarily affecting the Blue Mountains. Any accumulation snow
for the terminals should hold off until Monday morning. Peck

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  42  29  29  20 /  50  40  70  70
ALW  42  30  31  21 /  50  40  70  60
PSC  44  29  32  21 /  20  30  50  60
YKM  41  26  30  19 /  20  30  50  40
HRI  45  29  31  20 /  40  30  70  70
ELN  38  24  28  14 /  20  40  50  30
RDM  44  25  31  17 /  50  30  70  60
LGD  42  28  33  20 /  80  80  70  60
GCD  44  27  35  22 /  70  80  70  50
DLS  44  29  32  23 /  20  40  70  60

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Watch from late tonight through Tuesday afternoon
     for ORZ041-044-505-507>511.

 Winter Storm Watch from early evening through Tuesday afternoon
     for ORZ049-050-502-503-506.

WA...Winter Storm Watch from late tonight through Tuesday afternoon
     for WAZ024-029-521.

 Winter Storm Watch from early evening through Tuesday afternoon
     for WAZ030.

&&

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