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Area forecast discussion 
National Weather Service Pendleton or
156 am PDT Friday Aug 22 2014

Short through upper low pressure system
will settle southward today and move into the County Warning Area. This will spread
moisture and instability to northern areas of the forecast area.
There will be a slight chance to chance of showers and thunderstorms
from the eastern mountains and north central Oregon northward. The
best chance for thunderstorms will be from the Blue Mountains
eastward and the Washington Cascades/Simcoe Highlands and adjacent
valleys. Some storms could become strong but am not expecting severe
storms today. This scenario will persist this evening and then will
decrease to include only the northeast mountains overnight. The
upper low will continue to influence the County Warning Area on Saturday over the
northeast mountains where a mention of showers and thunderstorms
will continue. A northwest flow will develop by Saturday evening
resulting in drier and cooler weather. The County Warning Area will be precipitation
and thunderstorm free on Sunday morning. However...some residual
instability may result in a slight chance of thunderstorms over the
northeast mountains again Sunday afternoon east of the Blue
Mountains...otherwise elsewhere it will be dry and slightly cooler
than normal. Winds will generally be light through the short term
though there could be winds of 10 to 20 miles per hour at times during the
afternoons and early evenings. 88

Long term...Sunday night through Friday...a weather disturbance
embedded in the northwest flow aloft will affect mainly eastern portions of
the forecast area Sunday night and Monday with a slight chance for
showers and thunderstorms. This will be followed by a building upper
ridge for Tuesday and Wednesday with fair weather and warming
temperatures. Highs on Wednesday could be back into the middle 90s
lower elevations. For Thursday into Friday there is some
uncertainty. The operational run of the GFS sweeps a pretty strong
trough through the area with at least a slight chance for
thunderstorms and fire weather concerns due to wind and low relative
humidity. This is somewhat supported by the ensembles but many of
the members are slower with the trough and hold it offshore until
Friday. So for now went with a drier forecast on Thursday than what
the operational GFS would suggest and held off on the thunderstorms
until Friday. 78


Aviation...12z tafs...VFR conditions will prevail through 12z
Saturday. Expect increasing clouds throughout the day especially
north. There will be a cloud layer at 5-7 thousand feet above ground level with middle
clouds above. Scattered showers and a few thunderstorms will develop
over southern Washington and northern Oregon mainly this afternoon
and evening. They should be hit and miss so will use vcsh during the
peak chance at each taf site. Winds will be mainly northwest-north at 5-15 knots.



Preliminary point temps/pops...
PDT 79 58 79 56 / 20 40 10 10
alw 80 61 78 60 / 20 40 10 10
psc 82 60 82 59 / 20 20 10 10
ykm 79 58 81 56 / 40 30 10 10
hri 82 58 83 56 / 20 20 10 10
eln 78 55 80 55 / 50 30 10 10
rdm 74 46 74 45 / 10 10 0 0
lgd 73 51 70 49 / 30 50 20 20
gcd 73 49 70 50 / 20 20 10 10
dls 80 60 84 60 / 30 20 0 10


PDT watches/warnings/advisories...


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