Area Forecast Discussion
Issued by NWS Portland, OR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

FXUS66 KPQR 281018

Area Forecast Discussion
National Weather Service Portland OR
318 AM PDT Fri Jul 28 2017

.SYNOPSIS...An upper level trough over the NE Pacific will maintain
onshore flow with areas of low clouds night and morning low clouds,
especially near the coast and locally inland, through much of the
weekend. Look for slowly warming temps through the weekend. An upper
level ridge over the southwest U.S. will start to expand toward the
Pacific Northwest later in the weekend and then especially during the
coming week, pushing temperatures inland up into the 90s, possibly
even the upper 90s or even close to 100 during the mid week period
next week.

.SHORT TERM...Today through Sunday...An upper trough will continue
over the NE Gulf of Alaska today and into the weekend, lifting out
into Canada Sunday. This will maintain some onshore flow and keep
some night and morning low clouds and patchy fog at the coast,
locally inland in the mornings. There is a weak short wave aloft
along the coast this morning and slowly moving through the base of
the trough. This morning the main area of clouds is well offshore,
but we are seeing some clouds now forming along the coast and west
slopes of the coast range in the northerly low level flow. Clouds
inland are much more sparse but we could see some develop after
sunrise along the Cascade foothills. Clouds will tend clear faster
this morning than on Thursday with inland temps warming into the
lower to mid 80s.

Not a lot of change Saturday. A weak short wave still lingers near
the coast, and we should see some night and morning low clouds again
along the coast, and a little bit inland especially north. Again,
anything that forms should not last long with plenty of sunshine,
especially inland. Temps inland on Saturday should reach the mid to
upper 80s.

Sunday starts to see the upper high in the southwest U.S. expand
northwestward into the Pacific Northwest. After some local morning
low clouds, 500 mb heights approach 590 dm. Temps inland should reach
85 to around 90 based on 850 mb temperature considerations. Tolleson

.LONG TERM...Sunday night through Thursday...The upper level ridge
that strengthens on Sunday continues through much of the coming week.
500 mb heights approach the lower 590s. Despite the southwest flow
aloft, we should see less low clouds even at the coast as the marine
layer will be shallow. 850 mb temps are indicating temps inland will
be in the 90s, perhaps the upper 90s or even close to 100 during the
mid week period. We might start to see temps ease a little late next
week but still remain above normal. Tolleson

.AVIATION...Marine clouds have been slow to redevelop overnight,
leaving mostly VFR conditions over nw Oregon and sw Washington
through the early morning hours. Expect IFR to MVFR conditions to
redevelop along much of the coastal region through 14z this morning,
before breaking up again and improving to VFR conditions between 19z
and 21z. Over the interior, there will remain a chance for MVFR cigs
to redevelop after 12z this morning, with best chances along the
Cascade Foothills and affecting KTTD and KPDX. These clouds should
break up again by midday, between 17z and 20z. Marine clouds with
MVFR conditions are likely to redevelop along the coast again Fri
night after 03z, with a chance of MVFR cigs spreading up the Lower
Columbia as far as KPDX and KTTD after 11z Fri night.

KPDX AND APPROACHES...There is a chance for MVFR cigs to develop
this morning between 12z and 19z, otherwise expect VFR conditions
today. Tonight should remain VFR through most of the night, with a
chance for MVFR cigs to redevelop after 11z Fri night.

.MARINE...High pres will remain offshore, keeping winds generally
out of the north through the weekend and into early next week.
Strongest winds in general will be from the late afternoon through
the evening hours each day, and strongest over the waters off the
central Oregon coast as opposed to areas further north.  over the NE
Pacific, keeping winds out of the north to northwest. Winds will
generally peak during the afternoon and evening hours and generally
be strongest across the waters off the central Oregon coast versus
areas farther north. An area of low pres over northern CA will
strengthen this weekend, resulting in stronger winds gusting into
the 20 to 25 kt range. Seas will remain dominated by wind waves and
fresh swell resulting in short periods through the weekend and into
next week, but wave heights will remain 6 feet or less.



Interact with us via social media:

This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is
commonly referred to as the forecast area. is the U.S. government's official web portal to all federal, state and local government web resources and services.