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Area forecast discussion...updated 
National Weather Service Pendleton or
500 am PDT Friday Aug 28 2015

Updated aviation discussion

Short through Saturday night...strong shortwave trough
will move across the region on Saturday with general troughiness
remaining in its wake through Saturday night. For today and tonight
expect mostly cloudy skies with a chance of rain showers along the
Cascade crest. It will be a bit cooler today with highs mostly in
the 80s lower elevations and 70s in the mountains. On Saturday the
weather gets more interesting. As the trough moves through a cold
front will cross the region. This will bring a period of gusty SW
winds peaking in the early to middle afternoon. Wind advisories have
already been issued for a large portion of the forecast area. With
this forecast package will be issuing a blowing dust advisory for
Saturday for the Blue Mountain foothills...the lower Columbia Basin
and the Yakima Valley. Given the very dry conditions as of late it
appears likely that dust will be kicked up by the winds on Saturday.
The winds will also cause problems for the area wildfires with the
potential for the the fires to change direction and spread. The
weather is expected to quiet down quickly Saturday evening with
diminishing winds. There will be a continued chance of rain showers
along the Cascades. 78

Long term...Sunday through upper level trough will
remain over the Pacific northwest through the long term period. A
front will be moving through the trough on Sunday and will bring a
chance of rain from the Cascade crest east to the Yakima and
Kittitas valleys and south to central Oregon while further east will
see a slight chance of rain. Near the Cascade crest there will be up
to a quarter inch of rain but precipitation will drop off rapidly
away from the crest. Winds will be breezy on Sunday but much less
strong than on Saturday. The trough will flatten out Sunday night
and a westerly flow will be over the area. This will keep a slight
chance to a chance of rain in the Cascades while the rest of the
area remains dry. By Tuesday night another upper low will have
dropped south out of the Gulf of Alaska and into our area. This will
keep unsettled conditions through Wednesday night and the Cascades
and the eastern mountains will have a chance of rain while the rest
of the area has a slight chance of rain. Tuesday evening will see
breezy winds crossing the area. The upper low will retreat northeast
into Canada by Thursday and the trough will flatten out again.
Thursday will southeast a slight chance of rain in the Washington Cascades
and eastern mountains while the rest of the area remains dry.
Thursday and Thursday night a dry westerly flow will remain over the
area for fair weather. By Friday another low is sinking south
through British Columbia and the flow turns more to the southwest.
This is a more unstable situation and favorable for thunderstorms
but at this time showers and thunderstorms look like they will
remain north of the Canadian border. With the trough and cloudy
skies over the area Sunday, temperatures will be in the upper 60s
and 70s. Monday and Tuesday will warm a little to the middle 70s to
lower 80s but Wednesday through Friday will be back in the upper 60s
and 70s.


Aviation...12z tafs...VFR conditions will continue for the next 24
hours. Ceilings will be broken to overcast at 8k-15k feet above ground level. Smoke
from regional wildfires will continue to be present across the area
but are not expected to lower visibilities to MVFR at any taf site.
Showers will develop in and near the Cascades after 00z. Probability
of rain showers at any taf site is fairly low so have just mentioned
vcsh at krdm, kbdn and kdls. Winds will generally remain below 15
kts but kdls, krdm and kbdn could have gusts to 20 kts from 21z-04z.


Preliminary point temps/pops...
PDT 84 61 79 54 / 10 10 10 10
alw 86 67 79 60 / 10 10 10 10
psc 87 62 82 52 / 10 10 10 10
ykm 79 57 72 50 / 20 10 20 30
hri 86 63 80 53 / 10 10 10 10
eln 80 57 74 51 / 20 20 30 40
rdm 85 55 74 44 / 10 10 20 10
lgd 88 51 83 47 / 10 10 10 10
gcd 89 58 80 46 / 10 10 10 10
dls 84 63 78 60 / 20 20 40 30


PDT watches/warnings/advisories...
or...Wind Advisory from 5 am to 6 PM PDT Saturday for orz510-511.

Blowing dust advisory from 9 am to 6 PM PDT Saturday for orz044-

Wind Advisory from 9 am to 6 PM PDT Saturday for orz041-044-507-

Washington...blowing dust advisory from 9 am to 6 PM PDT Saturday for

Wind Advisory from 9 am to 6 PM PDT Saturday for waz024-026>029-


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