Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 242140 RRA
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
239 PM PDT Wed Apr 24 2019

.SYNOPSIS...Dry and mild weather continues through the first half of
Thursday, but increasing clouds with winds turning back onshore will
bring back cooler cloudy weather late Thursday through Friday. We
will see cooler temperatures with a chance for a few showers over the
weekend continuing into early next week.

&&

.SHORT TERM...Today through Saturday...Winds have already started to
turn weakly offshore inland, with winds gusting up to 20 kt south of
Salem. Will continue to see winds turn more offshore this evening as
a thermal trough builds up along the south Oregon coast. Offshore
winds will mean a clear skies to start the day on Thursday; however,
as the thermal trough shifts east of the Cascades by Thursday
afternoon we will see winds turn back onshore, bringing in clouds and
cooler temperatures starting late Thursday afternoon into Thursday
evening. The timing of this transition to onshore winds will be
crucial in determining how warm we get on Thursday. Right now
thinking most Willamette Valley locations will get into the low 70s,
but if winds turn onshore a little earlier than currently forecast,
temperatures could stay below 70.

Friday a weak upper-level front re-enforces mid and high-level cloud
cover over the region, but a significant dry layer above the surface
should inhibit any chance for precipitation with this system.
Saturday, a surface front brings a better chance for a few showers,
mainly north of Newport and Salem. There won`t be much precipitation
with this system, though, and most of the day will proably still be
dry. -McCoy

LONG TERM...Saturday night through Wednesday...West-northwest flow
aloft continues through the weekend and into early next week, leaving
the region vulnerable to shortwaves. However, models have been
trending drier, so continued that trend in the grids through Sunday
night. An upper trough dips south Monday, clipping western Oregon
before moving off to the east, so have some slight chance PoPs
Monday, but limited to inland SW Washington. Models aren`t in great
agreement about the positioning of the trough next week with respect
to how far east it will be. Went with a model blend for PoPs for
Tuesday and Wednesday, resulting in slight chance PoPs across most of
the local area. Any precip would be showery, so hit-or-miss by
nature, but there aren`t many days when slight chance PoPs actually
verify very well, so it`s a hedge for now between dry and higher
coverage showers. Bowen

&&

.AVIATION...Clear skies to continue through midday Thursday. Gusty
northerly winds this afternoon will start to diminish this evening,
but there should be enough of an offshore wind to keep skies clear
even on the coast through midday Thursday. Will start to see
increasing high-level clouds on Thursday afternoon with winds turning
west or northwesterly. VFR conditions through at least 00Z Thursday.

KPDX AND APPROACHES...VFR conditions through at least 00Z Thursday.
Clear skies through Thursday morning with increasing high-level
clouds Thursday afternoon. -McCoy

&&

.MARINE...Winds still gusting to around 25 kt across the waters
south of about Cascade Head and consistently right around 20 kt
north of there. Despite slightly lower winds north, will keep Small
Craft Advisory in place as is due to the potential for a small
increase in winds late this afternoon and evening. Winds become even
more marginal for an advisory by Thursday morning, so won`t extend
the current advisory longer. This summer-like north wind pattern is
forecast to persist into early next week. There are indications of a
strengthening thermal trough along the south Oregon coast Fri night
and Sat for potential 25 kt wind gusts again.

Guidance is reflecting current sea conditions a little bit better
today, although it`s hard to tell the difference between local wind
wave and fresh swell since there appears to be little background
swell. Expect this trend to continue for the next few days.
Conditions could get close to square-sea criteria, especially over
the south waters where the highest wind waves will exist. Bowen

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory for winds until 5 AM PDT Thursday for
     Coastal Waters from Cape Shoalwater WA 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. This area is
commonly referred to as the forecast area.


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