Strong Wind in Washington, April 29, 2019

Area Forecast Discussion
National Weather Service Portland OR
205 PM PDT Mon Apr 29 2019

.SYNOPSIS...There will be little change in the weather the next few
days with dry and mostly sunny weather persisting. Onshore winds
return Tuesday night for cooler conditions on the coast. A marine
push Wednesday night will increase clouds and result in slight
cooling inland on Thursday.

&&

.SHORT TERM...This afternoon through Thursday...Satellite imagery
this afternoon shows some cumulus clouds forming over the terrain of
the Cascades as well as the areas near the Oregon/Washington border.
Radar shows some showers beginning to pop up to our north in the
Washington Cascades. Could still see a couple of showers around Mt.
St. Helens this afternoon, but chances remain low. Elsewhere, dry
offshore flow will keep skies clear and winds a little bit breezy at
the surface.

With dewpoints in the 20s this afternoon, don't expect any fog
tonight. Good radiational cooling will mean another chilly night with
lows around 40 degrees, generally about 5 degrees below seasonal
normals and similar to this morning.

The thermal trough weakens and moves inland Tuesday evening,
returning onshore flow Tuesday night and Wednesday. This will cool
temperatures along the coast, and possibly increase marine clouds.
Models hint at a deeper marine push Wednesday night into Thursday as
another shortwave trough moves over the area. This will likely
increase sky cover inland, and generate afternoon showers for the
south Washington Cascades again. Bowen

.LONG TERM...Thursday night through Monday: Much of the uncertainty
from yesterday's model runs has transformed in to much better
agreement. The ECMWF has trended toward the GFS by bringing a closed
low starting off near 35N/140W now toward and now crossing the
central California coast sometime Sunday morning. The overall trend
of bringing the low onshore is now slower and further north than
yesterday's GFS run which bodes well for keeping the region dry
heading into the weekend. Concurrently, the offshore blocking upper
ridge is appearing a little stronger as well.

Onshore flow would normally mean morning clouds and afternoon sun
under this pattern, however, we will remain under a fairly dry air
mass which will mean minimal clouds overall and pleasant
temperatures in the upper 60/lower 70s through Monday. The only
chance for precipitation will be on Sunday late afternoon and early
evening should the aforementioned upper low drift closer the the
PacNW as of now, only the area near Willamette Pass may get some
showers. Should the low drift further north on Sunday, then would
expect more areas west of the Cascades to pick up showers. There
might also be enough instability introduced to warrant thunderstorm
mentions. Certainly not enough threat to include in the forecast
just yet. /JBonk

&&

.AVIATION...VFR conditions continue through the next 24 hours. We
will have another round of breezy northerly winds to 20 kt
between 29/20Z and 30/04Z. We may see some patchy high clouds
tonight as a weak disturbance passes to our north.

KPDX AND APPROACHES...VFR the next 24 hours. Expect another
round of breezy northerly winds to 20 kt between 29/20Z and
30/04Z. -McCoy

&&

.MARINE...High pressure stays over the northeast Pacific through
the week. Today should be our final day of advisory winds to 25
to 30 kt and steep seas as the thermal low over southern Oregon
starts to really weaken. After tonight, winds and seas stay
fairly benign through the end of the week, with winds generally
less than 20 kt and seas around 3 to 6 feet. -McCoy

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory for winds until 4 AM PDT Tuesday for
     Waters from Cascade Head to Florence OR from 10 to 60 NM.

     Small Craft Advisory for hazardous seas until 4 AM PDT Tuesday
     for Waters from Cascade Head to Florence OR from 10 to 60
     NM.

     Small Craft Advisory for winds until midnight PDT tonight for
     Coastal waters from Cascade Head to Florence OR out 10 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.