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 29

FXUS66 KPQR 022119

Area Forecast Discussion
National Weather Service Portland OR
216 PM PDT Sun Oct 2 2022

.SYNOPSIS...High pressure over the region will maintain warm and dry
conditions for much of southwest Washington and northwest Oregon
through at least the first week of October.


.SHORT TERM...Tonight through Wednesday...Models and their
ensemble systems are in good agreement shortwave ridging over the
northeast Pacific will gradually shift eastward across the PacNW
through midweek. As such, it should generally remain dry and mild
with cooler temperatures along the coast.

A southerly wind reversal is currently resulting in clouds and fog
spreading northward up the Pacific Northwest coast. These marine
clouds will deepen a bit late Monday into Tuesday as a weak storm
system lifts northeastward off the Oregon/Washington coast. The
majority of the raw ensemble members suggest measurable
precipitation will fall at most coastal sites during this time.
Meanwhile, NBM4.0 guidance suggests PoPs of 0-1% while NBM4.1 PoPs
are generally in the 30-50% range along the coast. Opted to split
the difference and add a slight chance mention of drizzle/rain to
the immediate coastline late Monday through Tuesday to account for
this possibility. Otherwise, expect some of this cooler marine air
to gradually filter into the Willamette Valley and Columbia River
Gorge and result in high temperatures cooling into the upper 70s to
near 80F by midweek. /Neuman

.LONG TERM...Wednesday night through Sunday...Models and their
ensembles are more or less in agreement the region will remain warm
and dry through next weekend as upper level high pressure lingers
across the Pacific Northwest. There is a small percentage (<20% of
the ensemble members) that either shift the ridge far enough east or
flatten the ridge just enough that some light precipitation could
reach the area as early as Sunday, but again the probability of this
occurring appears low at this point. /Neuman


.AVIATION...IFR/LIFR conditions along most of the coast with VFR
under clear skies inland. These conditions are expected to
continue through the remainder of the daytime hours.

HREF and model guidance continue to show the southerly winds
along the coast acquiring a slight westerly component this evening.
This will result in a marine stratus push into the southern and
central Willamette Valley starting around 06Z Monday. There is a
30%-50% chance for cigs below 1000 ft working into both the
southern and central Willamette Valley with a slightly higher
likelihood for areas near KEUG. There is a low chance, around 10%,
that the marine push could result in cigs around 1000 ft
impacting KPDX and other TAF sites in the northern Willamette
Valley. Any lowered flight conditions for inland areas will likely
scour out by 18Z Monday.

For detailed Pac NW aviation weather information, go online to:

KPDX AND APPROACHES...VFR flight conditions under clear skies.
Around a 10% chance that the marine push tonight could result in
cigs around 1000 ft and impact KPDX starting around 15Z Monday.
Any lowered flight conditions will likely scour out by 18Z Monday.


.MARINE...Widespread marine stratus continues across all waters
as a moderate southerly surge continues through the beginning of
this week. Looking at cameras located on buoys as well as
observations from the USCG has supported keeping the current Dense
Fog Advisory for all waters and the Columbia River Bar. This will
likely continue through 3 PM Monday as minimal change is
forecasted. However, the situation will continue to be monitored
to see if adjustments need to be made.

Otherwise, a persistent northwest swell will keep seas around 4
to 6 ft at 10 to 12 seconds through the middle of the week.
Southerly winds generally remain less than 15 kt through early
Wednesday afternoon. A northerly wind shift is expected as a weak
frontal passage is forecasted to cross the waters Wednesday. /42

For information about recent marine zone changes, go online to:



PZ...Dense Fog Advisory until 3 PM PDT Monday for coastal waters from

     Cape Shoalwater WA to Florence OR out 10 nm.Columbia River
     Bar-Coastal waters from Cape Shoalwater WA to Florence OR
     from 10 to 60 nm.


Interact with us via social media: is the U.S. government's official web portal to all federal, state and local government web resources and services.