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Area forecast discussion 
National Weather Service Pendleton or
216 am PST Friday Feb 12 2016

Short term...today through Sunday...a weak warm front which brought
some rain to the forecast area has moved off to the northeast. There
is a weak cold front that will move across the County Warning Area today...but it is
weakening as it advances eastward. Radar imagery is showing some
echo returns moving east of the Cascades into the western portions
of the County Warning Area...especially in Washington at this time. This will bring
some light rain showers to the County Warning Area mainly this morning and then some
drying this afternoon. The flow aloft has become southwest so there
will remain some moisture over the County Warning Area through the day with mostly
cloudy skies. Another weak cold front will move across the County Warning Area this
evening with some more showers...except dry in the Yakima and
Kittitas valleys where there will be some rain shadowing from the
flow off the Cascade Range. Then on Saturday a weak open upper
trough will move across the County Warning Area with perhaps more showers mainly in
the mountains. An upper ridge will then try to build over the region
but it will be a dirty ridge with significant amounts of moisture
moving through it with a couple of weather systems that will move
through this ridge Saturday night and Sunday. Will have chance to
likely probability of precipitation across the County Warning Area Saturday night. Quantitative precipitation forecast guidance shows at
least a half inch to an inch of rain over the northeast mountains
and along the Cascade east slopes...with lesser amounts in between.
Then the second weather system will move into the County Warning Area by late Sunday
and continue into the extended period with more rain. Snow levels
will be quite high today but then will drop to around 4000 feet
tonight allowing the higher mountains to receive some snow with
light accumulations. The lower snow levels will persist through
Saturday night. Then snow levels are expected to Jump Up again to
around 6000-7500 feet mean sea level on Sunday which will ensure that most
precipitation on Sunday will be rain except over the highest peaks.
Winds will be light today through early Saturday morning...except it
will be breezy at times in the southern Grande Ronde Valley. Winds
will then increase with the weather system coming in Saturday night
and again to a lesser degree on Sunday. Maximum temperatures through
the short term period will be above normal with mostly 50s each day
in the lower elevations and 30s to middle 40s in the mountains.
Overnight lows will be mild as well with mainly 40s in the lower
elevations and upper 20s to upper 30s higher terrain. An air
stagnation advisory will remain in effect for much of the County Warning Area
through late morning Saturday. 88

Long term...Sunday night through Friday...progressive
west/northwest flow continues as high pressure to the south shifts
over southern CA/NV/AZ. Sunday night into Monday morning will still
have decent moisture associated...but drier air will attempt to
intrude as we move into middle day Monday and Tuesday. For this probability of precipitation
have been scaled back a bit from previous forecast. Also...winds
aloft expected to range from 30-50kts and may mix down to make for
breezy to windy conditions across the lower elevations Monday
afternoon and evening.

As we move into middle week on Wednesday...the high pressure will have
shifted far enough east that our area will start to move into a
moist southwest flow. Probability of precipitation have picked up for this time
period...but snow levels will still remain above 7000 feet mean sea level...and
will lower slightly Wednesday evening. The cold front that previous
models had moving in on Thursday has now been backed off until
Friday night into Saturday. As a result have adjusted snow levels
to remain above 5000 feet mean sea level through the extended forecast. Weber

&&

Aviation...12z tafs...recent precipitation has moistened up the
lower levels...with clearing skies allowing for fast radiational
cooling. This has resulted in fog for several taf sites. There
area still a few showers in the vicinity of kykm...otherwise most
precipitation is isolated to northwest Washington. Expect various
categories from VFR/LIFR over the next 6 to 12 hours. Right now it
is hard to stay consistent with cigs/vis...therefore expect
amendment to tafs as the changes come in. Hopefully after 18z there
will be enough heating to mix out the status. Weber

&&

Preliminary point temps/pops...
PDT 52 39 55 42 / 10 30 10 70
alw 52 43 55 44 / 10 30 20 80
psc 51 38 56 41 / 10 20 10 50
ykm 48 33 52 34 / 20 10 10 40
hri 52 39 56 41 / 10 20 10 50
eln 44 33 46 34 / 20 20 20 50
rdm 56 31 52 37 / 20 20 10 40
lgd 51 34 49 37 / 10 40 20 70
gcd 54 33 50 36 / 10 20 10 60
dls 54 40 54 40 / 40 30 20 50

&&

PDT watches/warnings/advisories...
or...air stagnation advisory until 10 am PST Saturday for orz041-044-
050-505-507-508-510.

Washington...air stagnation advisory until 10 am PST Saturday for waz024-
026>029-520-521.

&&

For additional weather information, check our web site at...
www.Weather.Gov/Pendleton

$$

88/89/89

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