Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 030310

Area Forecast Discussion
National Weather Service Pendleton OR
710 PM PST Fri Dec 2 2016

.UPDATE...A weak weather disturbance continues to move across the
forecast area this evening. It is producing very little in the way
of precipitation and mostly just clouds. There have been a few light
showers though near the Washington Cascade east slopes. This system
will move to the east later tonight and be replaced by a northwest
flow for Saturday. The next system will move into the region from
the northwest on Saturday night into Sunday. It will have more
abundant precipitation and bring more substantial snow to the
mountains (mainly above 3000-3500 feet) and rain to the valleys and
basins below that level. A strong cold front will follow this on
Monday with much colder air behind it and possibly with a little
light snow...especially in upslope areas into the eastern mountains
and Cascades. The cold weather will then persist through most of the
week with more wintry precipitation expected later in the week. 88


.AVIATION...06Z TAFs...VFR conditions will prevail though there may
be brief periods of MVFR conditions tonight as a weak disturbance
moves across the region. Generally fair weather with VFR conditions
will persist through Saturday evening. Winds will be mostly light
through Saturday morning but then they will become westerly 15-25
kts at KPSC...KPDT...KALW and possibly KDLS after 18Z Saturday. 88


.PREV DISCUSSION... /issued 356 PM PST Fri Dec 2 2016/

SHORT TERM...Tonight through Monday. A disturbance was moving
through a ridge of high pressure over the pacnw today. The latest
radar was showing little in the way of pcpn but as the moisture
moves into the blue mountains...the upslope flow should create some
mountain showers into tomorrow morning when the flow weakens.
Another ridge of high pressure returns and mainly dry conditions
persist except for the area mountains that may continue to
experience a shower on Saturday.

Meanwhile a storm system takes aim of the two state area Saturday
night with showers increasing in coverage and intensity into Sunday.
As the storm system tracks through the region...its associated cold
front will bring colder temps with lowering snow levels. Several
inches of snow are possible above 2500 feet along the east slopes of
the cascades and above 3500 feet in the blue/wallowas into Sunday
night. In addition pressure gradients tighten and breezy conditions
are expected Sunday aftn/eve.

LONG TERM...Monday through Friday...An active weather pattern will
bring cold and unsettled weather for most of the long term period.
Models have slowed down the arrival of a system on Monday so have
cut back on a slight chance of snow showers to the western third of
the area in the morning and then have a chance of snow showers
across the area Monday afternoon and night. Temperatures will be in
the 30s with mid 20s to lower 30s in the mountains in the morning
but will be falling in the afternoon as the front moves in. Monday
night temperatures will be in the mid teens to mid 20s.
Precipitation amounts will be light on Monday and increase Monday
night. At this point it looks like an inch or two of snow in the
lower elevations and a little more than that in the mountains. A
trough will remain over the area Tuesday with a northwest flow over
the area. This will create upslope showers and there will be a
chance of snow showers in the mountains and slight chance in the
Blue Mountain foothills. Snow showers will taper off Tuesday
evening. A ridge will build over the area for dry weather and
continued cold temperatures on Wednesday. Highs will be in the 20s
and lower 30s. Models continue to have differences about a system
arriving either Wednesday night in the GFS or Thursday afternoon in
the ECMWF. This system will bring another trough through the area
with snow showers continuing into Friday. Have not tried to pin down
the exact timing and have a chance of snow (with a rain/snow mix
during the daytime in the Lower Columbia Basin) from Wednesday night
through Friday. Temperatures will warm a few degrees each day with
highs in the upper 20s and 30s Thursday and in the 30s and lower 40s
on Friday. Perry


PDT  35  48  39  46 /  20  10  30  60
ALW  38  50  41  47 /  30  10  40  60
PSC  36  50  40  46 /  10  10  20  40
YKM  31  49  33  42 /  10  10  20  40
HRI  34  49  39  47 /  10  10  20  50
ELN  31  45  32  40 /  20  10  20  40
RDM  26  45  32  45 /  10  10  20  60
LGD  33  42  34  41 /  30  20  40  70
GCD  28  39  34  39 /  30  20  20  60
DLS  37  51  40  45 /  20  10  40  60





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