Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 201059
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
259 AM PST Tue Feb 20 2018

.SHORT TERM...Today through Thursday...The Pacific Northwest will
continue to be on the western edge of a trough over the Rockies with
a ridge offshore in the Eastern Pacific for the next few days. A
northerly flow will keep well below normal temperatures over the
area with highs in the mid 20s to mid 30s today and tomorrow then
warming a couple of degrees Thursday to the mid to upper 30s in the
Columbia Basin and in the mid 20s to lower 30s elsewhere. Lows will
be in the mid teens to lower 20s with 5 to 15 in the mountains.
Today will be dry and partly cloudy. However, by this afternoon a
wave will move south along the coast and this will help trigger snow
tonight and tomorrow morning over the western half of the area
especially in the Oregon portion. The Columbia Basin will be mainly
dry and the eastern mountains will just have a slight chance of
light snow. Snow amounts will be generally 2-4 inches in the
Columbia Gorge, North Central and Central Oregon and the Southern
Blue Mountain Foothills near Condon and Fossil. The East slopes of
the Oregon Cascades south and west of Bend will get 4-6 inches of
snow. Will issue a Winter Weather Advisories for those zones for
tonight and tomorrow morning though the amounts are just at advisory
criteria, so it`s a marginal event. Other areas will get anywhere
from a dusting to an inch or two. Wednesday will be a break between
waves and most of the area will be dry while lingering upslope
showers in Central Oregon and the mountains will bring another
quarter to half inch of snow. Another wave moves down the trough and
into the area Wednesday night and Thursday with a chance of snow
mainly in the Cascades and the Oregon portion of the area. Snow
amounts look lighter with this wave but the mountains and Central
Oregon could get another inch or two. Perry


.LONG TERM...Thursday night through Monday...The region will be on
the back side of a large upper level trough over the Great Basin
Thursday night with just a slight chance for evening snow showers
south and east. Otherwise another system will drop sewd in the nwly
flow aloft Friday afternoon and night and spread snow across mainly
the mountains with snow levels below 1000 feet. A stronger shortwave
will move across the area Saturday and Saturday night with a good
chance of snow in the mountains and rain/snow in the lower
elevations. Snow levels will be 1-2 thousand feet. Yet another
trough will move across the region on Sunday with snow in the
mountains and rain below about 1500 feet. By Monday the trend will
be for drier conditions as an upper level low develops off the coast
and focuses the moisture west of the forecast area. There will be
periods of breezy/windy condition`s over the weekend as each storm
moves through. 78


&&

.AVIATION...12Z TAFS...VFR conditions will prevail through the
period. A storm system will drop south along the Oregon Cascades
this evening and overnight. This will spread snow across
KDLS...KRDM...and KBDN after 01Z. MVFR/IFR conditions will be
possible in heavier snow. At the other TAF sites expect a few
stratocumulus today and then increasing mid and high clouds this
afternoon and evening.  Winds will be light. 78


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  33  15  33  18 /   0  20  10  10
ALW  35  18  34  20 /   0  20   0  10
PSC  36  19  37  20 /   0  10   0  10
YKM  34  19  35  21 /  10  20   0  20
HRI  36  18  36  21 /   0  20   0  10
ELN  32  14  33  17 /  10  20   0  10
RDM  33  14  31  13 /  10  70  40  20
LGD  28  15  30  17 /   0  40  30  20
GCD  29  17  31  17 /   0  50  60  20
DLS  37  20  37  23 /  20  60  10  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory from 4 PM this afternoon to 10 AM PST
     Wednesday for ORZ041-508-510.

     Winter Weather Advisory from 4 PM this afternoon to noon PST
     Wednesday for ORZ509-511.

WA...Winter Weather Advisory from 4 PM this afternoon to 10 AM PST
     Wednesday for WAZ024.

&&

$$

83/78/78



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