Area Forecast Discussion
Issued by NWS Portland, OR

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599
FXUS66 KPQR 260932
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
232 AM PDT Tue Jul 26 2016

.SYNOPSIS...A weak upper trough near the coast with a weak westerly
flow aloft over the Pacific Northwest will continue today into early
Wednesday with morning low clouds giving way to afternoon sunshine
and seasonable afternoon temperatures. An upper level ridge will
build for the second half of the week and bring inland highs well
into the 90s Thursday and Friday before the next trough arrives to
moderate temperatures and increase clouds over the weekend.
&&

.SHORT TERM...(Today through Thursday)...Another weak upper
disturbance will move through the Pacific Northwest in a light
westerly flow today, maintaining onshore flow. The models suggest
more coverage of low clouds inland this morning as compared to Monday
morning and the fog channel satellite imagery is supporting that
trend. Don`t believe they will fill the inland valleys, but there
should be more coverage especially north but also some extending
south along the Cascade foothills into parts of the central
Willamette Valley. The clouds should burn back to near the coastline
again today in the north and a bit offshore along the central Oregon
coast today. Expect temps 4 to 6 degrees lower than Monday in the
north valley but only a couple of degrees cooler at Eugene.

The models show one last weak disturbance currently out near 40n/140w
moving through southwest Washington and northwest Oregon later
tonight and Wednesday morning. This should spread more low clouds
onshore again Wednesday morning especially in the north, but coverage
in the south is forecast to be a bit less. The models suggest pretty
good clearing again Wednesday afternoon with some lingering low
clouds along the north coast. The air mass warms a touch Wednesday
and expect temps to warm close to those of Sunday and Monday in the
south valley and approach those values in the north valley.

The upper ridge builds some by Thursday with less coverage of morning
low clouds Thursday morning, mainly north coast and locally inland
along the Columbia River. The models indicate we have a good chance
of seeing the first of a two day stretch of low to mid 90s inland on
Thursday. Tolleson

.LONG TERM...(Thursday night through Monday)...The models are showing
one more very warm day on Friday but now with temps similar to those
on Thursday, perhaps not quite as hot as previously thought as
westerly flow continues and ridging is not quite as pronounced. The
models are continuing to show an upper trough beginning to drop down
the B.C. coast Saturday and swing through the Pacific Northwest
Sunday and early next week. The ECMWF continues to be the weaker
model with this pattern, but is getting closer to the GFS while the
GFS is not quite as strong as it had been. This convergence of the
models lends increasing confidence in a cool down this weekend,
perhaps with some drizzle near the coast by Sunday. We will have to
see whether we can sneak any showers out of this pattern early next
week. Tolleson
&&

.AVIATION...IFR to low end MVFR clouds have remained packed onto most
of the coastal areas this evening. With onshore pres gradients
generally stronger than the same time last night, expect MVFR marine
clouds to spread into the north Willamette Valley late tonight and
Tuesday morning. Lower confidence about other areas in the valley,
but think KEUG will likely see an MVFR ceiling after 13Z as well.
Expect whatever develops inland to break up and return to VFR
conditions between 18Z and 21Z Tue. Along the coast MVFR and pockets
of IFR cigs are likely to continue through the day Tue.

KPDX AND APPROACHES...Marine clouds with MVFR cigs expected to
develop late tonight and Tue morning between 12Z and 14Z, then break
up again between 19Z and 21Z. Bowen
&&

.MARINE...There will be little change the next several days as north
winds persist over the waters and fresh swell remains the primary sea
influence. The thermal induced trough of low pres will continue to
expand slightly north in the afternoons and evenings for an increase
in gusty winds, with the strongest pres gradients south of Cascade
Head. Have issued a Small Craft Advisory for Winds with gusts 25-30
kt expected this afternoon through at least tonight across the waters
off the central OR coast. The trough will expand further north Wed
through Fri for continued small craft winds for the N OR/S WA waters
in the afternoons and evenings.

Seas around 6 ft tonight will remain in the 6-7 ft range through at
least Wednesday, but will steepen later Tuesday as wind wave becomes
dominant. Will have to keep an eye out for 7 ft/7 sec square seas as
winds pick up later today, but will not issue an advisory for seas at
this point. Bowen
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory for winds from 3 PM this afternoon to 4 AM
     PDT Wednesday for Coastal Waters from Cascade Head OR to
     Florence OR out 60 nm.

&&

$$

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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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