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Area forecast discussion...updated 
National Weather Service Pendleton or
353 PM PST Thursday Feb 11 2016

Updated aviation discussion

Short term...tonight through Saturday night...a warm front
associated with the next Pacific system is currently moving north
across the Pacific northwest. This front will continue to move
through northeast Oregon and southeast Washington late this
afternoon and early this evening. Thus will see light showers
gradually lift north out of much of the area by middle evening. A few
showers should linger over the northern blues, near the Oregon
Cascades and over portions of southeast Washington overnight. Low
level inversions will continue over portions of the basin, and some
patchy fog will again be possible overnight into Friday morning.
Thus will also continue the current air stagnation advisories. The
cold front associated with this next system will move across the
region Friday afternoon and evening. This system will spread more
precipitation across the area. Will see snow levels lower behind the front.
Also should see winds over portions of the area increase behind the
front. A few showers will linger Saturday over the mountains.
Meanwhile should see breezier winds and better mixing at most
locations, though mixing may remain limited in the Yakima and
Kittitas valleys. Another warm front is expected to move across the
region Saturday night bringing another round of precipitation. Snow levels
Saturday night will run around 4000 feet. 90

Long term...Sunday through Thursday...a west to northwest flow will
provide ample moisture as a series of disturbances ride over an
offshore ridge. This will lead to a chance for mainly rain showers
at times. Sunday will see a cold front cross the area as a ridge
builds offshore. Snow levels will remain around 4000 feet in the
morning then rise to 6000-7000 feet in the afternoon. This will give
US a chance of rain across the area and the mountains will have a
chance of of up to an inch or two of snow in the morning. The
strengthening offshore ridge will lift the front north out of the
area Sunday night with a continued chance of rain in the mountains
and a slight chance in the lower elevations. Monday through Tuesday
the ridge will deflect systems to our north and we will be dry aside
from a chance of showers along the Cascade crest and a slight chance
of showers in the eastern mountains. Tuesday and Tuesday night an
approaching trough will push the ridge across our area and off to
the east. Models differ as to when a front associated with the
trough will cross the area. The GFS brings it in Wednesday and
Wednesday night with the trough moving through behind the front on
Thursday. The European model (ecmwf) has a stronger system further south with it
moving into the area Wednesday night and Thursday. Both situations
would mean a chance of rain across the area with snow levels around
6000-7000 feet initially before dropping to 3000-4000 feet with the
trough passage. Have leaned towards the GFS timing and have a chance
of rain Wednesday through Thursday with a chance of mountain snow in
addition by Thursday. Temperatures Sunday will be in the lower to
middle 50s with middle 40s to middle 50s in the mountains. With the influence
of the offshore ridge temperatures will soar Monday and Tuesday to
upper 50s to middle 60s with upper 40s and 50s in the mountains. A few
places may see record high temperatures on these days. Wednesday and
Thursday will drop back the 50s with mainly 40s in the mountains.


Aviation...00z tafs...VFR conditions will be predominant for the
next 24 hours. A warm front is crossing the area this evening and
will bring occasional showers mainly to the northern half of the
area through 03z-05z affecting all taf sites except krdm, kbdn and
kpsc. Another disturbance will bring more showers after 15z-18z
tomorrow morning affecting all taf sites. Ceilings will be broken-overcast
at 4000-10000 feet above ground level in general, though kykm and kdls may get MVFR
ceilings and visibilities due to fog from 11z-18z. Kdls may also get
MVFR ceilings with -shra from 16z-21z. Winds will remain below 15
kts for the next 24 hours. Perry


Preliminary point temps/pops...
PDT 40 53 39 53 / 20 30 50 10
alw 43 53 43 53 / 20 40 50 20
psc 39 52 38 56 / 20 40 30 10
ykm 38 49 33 52 / 40 30 20 10
hri 40 53 39 56 / 20 40 40 10
eln 33 45 33 46 / 50 40 20 20
rdm 36 57 31 52 / 10 30 30 10
lgd 38 52 34 49 / 20 20 40 20
gcd 38 55 33 50 / 10 10 30 10
dls 41 55 40 54 / 30 40 30 20


PDT watches/warnings/advisories...
or...air stagnation advisory until 10 am PST Saturday for orz041-044-

Washington...air stagnation advisory until 10 am PST Saturday for waz024-


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