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Area forecast discussion 
National Weather Service Portland or
242 PM PDT Thursday Aug 28 2014

Synopsis...upper ridge that has been responsible for the warm
weather will weaken and shift eastward through Friday. This will allow
for westerly flow off the North Pacific to arrive...bringing cooler air and
even a threat of showers for this weekend. Dry weather resumes next
week...with more seasonable temperatures for early September.


Short term...a line of cirrus denoting a very weak front could be
seen earlier today moving through the forecast area and can still
faintly be made out on visible satellite stretching from about
Hermiston back to Eugene. However...the front brought essentially no
sensible weather changes. Behind the front...marine push tonight
will be stronger and bring clouds over most of the area but also
cool marine air. Low temperatures should be similar to this morning
and then highs Friday will be cooler than earlier this

A stronger front..currently located off the southern British Columbia coast...comes
through late Friday with some shower chances along the coast in the
afternoon. Models do not show a lot of available moisture east of
the Coast Range Friday night...but added a slight chance of showers
over the Cascades anyway following the thought that enhanced upper
level forcing will only increase an already existing chance of
orographic showers. Slight chance probability of precipitation continue over the northern
forecast area Sunday as another weak trough moves through. Light
rain showers are the expected precipitation type for anything that does
develop during the short term period and no significant
accumulations are expected. Bowen

Long upper level ridge will build into the region next
week. This will give US a slight warming trend through
Wednesday...however...temperates will still be near seasonal
normals. With northwesterly flow aloft and a slightly progressive
weather pattern we could see a slight chance of showers along the
Washington and Oregon border and into the northern Cascades for
much of next week. The timing and location of these showers are
still uncertain as both the GFS and European model (ecmwf) have slightly different
forecast. These will be further refined with future updates. /64

Aviation...satellite imagery shows the low clouds along the
north coast have lifted to a scattered deck in response to a weak
front that moved through the region earlier today. Expect VFR
conditions across the region through the remainder of the
afternoon into early evening. The marine stratus will move back
into the coast after 02z-03z with IFR conditions overnight.
Models indicate the marine layer will deepen tonight and push
further into the Willamette Valley late tonight into Friday

Kpdx and approaches...VFR conditions this evening and most of
tonight. Expect the marine stratus to push into the terminal early
Friday morning bringing MVFR ceilings 11z-13z time frame.


Marine...a series of weak fronts will move across the waters
through the weekend...and maintain a weak surface pressure
gradient. Winds will remain around 10 knots out of the northwest...briefly
shifting west and SW with each frontal passage. The seas will
comprise of a small SW swell and steep wind waves the next couple
of days. A northwest swell will build Saturday night and peak around 7
feet on Sunday. High pressure will rebuild Monday night and
Tuesday and persistent northerly winds will return to the waters.


Pqr watches/warnings/advisories...


Pqr watches/warnings/advisories...


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This discussion is for northwest Oregon and southwest Washington
from the Cascade crest to 60 nautical miles offshore. The area is
commonly referred to as the forecast area.

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