Area Forecast Discussion
Issued by NWS Portland, OR
FXUS66 KPQR 240415
Area Forecast Discussion
National Weather Service Portland Oregon
913 PM PDT Sun Oct 23 2016
.SYNOPSIS...A low complex developing offshore this afternoon will
remain a few hundred miles offshore through Tuesday. A cold front
that will stay mostly offshore tonight may produce rain for the coast
and coast range this evening. The front will move onshore for more
widespread rain on Monday. The low will move to the north Monday
night and bring a burst of gusty south winds and large surf to the
beaches late Monday night. Another low will approach form the south
on Tuesday and likely bring a moister frontal system to the area
Tuesday night through Thursday.
.SHORT TERM...Tonight through Wednesday...A low complex is developing
several 100 miles off of the Oregon coast this afternoon. The
surface low associated with a weak cold front just offshore earlier
today is entraining back around the broad Pacific low allowing the
front to stall offshore. This continues this evening, but a
shortwave trough and surge of moisture wrapping around the broad low
further offshore is now moving along this front. Through the
remainder of tonight the bulk of the rain remains offshore and
skirting the coastal zones. NWS network radar showing some light
echoes appearing in the south part of the forecast area so may see
some sprinkles for the interior zones as well tonight.The next
front can be seen on satellite imagery with the low center 42n/132w.
This will lift toward the forecast area tonight and onshore Monday
morning. The models are consistent that the bulk of the moisture with
this front will move into south Oregon and north California, but
light rain will still make it to the Portland forecast area. The
coast should see rain mid Monday morning with inland areas Monday
afternoon. The Central Oregon coast and coast range will have the
highest rainfall totals with 0.25 to 0.50 inch possible Monday
morning through Monday afternoon. The Cascades may also see similar
amounts with snow levels around 7000 feet.
There will be a burst of gusty south winds along the beaches and
headlands Monday night with wind gusts flirting with warning
criteria. High surf also remains a potential beach hazard Monday
The low will move north Monday night and Tuesday pulling the showers
back offshore. Most inland areas will be on the dry side Monday night
through Tuesday. Another closed low will approach from the south
Tuesday and bring a moister warm front to the region Tuesday night
and Wednesday. TJ /mh
.LONG TERM...Wednesday night through Sunday...A complex weather
pattern continues offshore late in the week into next weekend. The
low that will bring rain to the area Wednesday moves north Wednesday
night and brings a cold front across the region on Thursday. The low
then moves inland as an open trough Thursday night as two other
Pacific lows move into the offshore waters. One low approaches from
the south, and another larger low approaches from the northwest. This
will result in dry weather for the Portland forecast area Thursday
night. The northern low deepens over the ne Pacific Friday allowing
an upper ridge to amplify over the Pacific NW, and keeping the
southern low south of northwest Oregon. The southern low moves inland
across north California and east Oregon Friday or Saturday for
showers over the Portland forecast area. The second low then moves
onshore on Sunday for a continued threat of rain. Snow levels will
remain well above the Cascade passes. TJ
.AVIATION...Rather benign tonight with light southerly flow aloft
and light east to southeasterly flow in lower levels. However some
gusty winds near the western end of the Columbia River Gorge.
Will see generally VFR tonight with variable mid/high clouds. May
see some patchy fog in inland valleys but not much. Front
approaching region Mon am, with clouds lowering to low VFR. May see
areas of MVFR along the coast with light rain after 12z. This rain
will spread inland through Mon am, but conditions look to remain
VFR over much of the interior on Mon.
KPDX AND APPROACHES...Winds out of the east will pick up at some
point tonight and may see gusts to around 20 kt for a few hours.
Clouds and vis should remain VFR. Bowen/Rockey
.MARINE...Not much in way of change to the current forecasts and
warnings. Generally south to southeast winds 15 kt or less into
this evening, with seas 5 to 7 ft.
An occluded front will push across the region later tonight into
Mon am. Southerly winds will increase over the central waters with
20 to 25 kt winds and gusts 30 to 35 kt. These winds will
gradually spread northward tonight as the front pushes closer to
the coast. Current gale warning looks on track so no changes. Seas
will climb back to 12 to 15 ft range, with higher seas over the
Now, will see rather active storm pattern over the NE Pac this
week, with several very strong storms arriving. But the low
centers will remain well offshore, mostly tracking north along
130W. This will maintain decent gradients over the coastal waters,
with gales continuing on Mon, and likely through Wed at times.
Models continue to suggest increasing potential for storm force
wind gusts, especially over the outer waters for Mon night. Have
issued a storm watch for the outer waters for Mon night, with
gusts 50 to 55 kt possible at that time. Still think that closer
to shore waters will see less wind, with gusts 40 to 45 kt. So
will maintain gale warning in the inner coastal waters.
Seas will be on the increase with all the increased winds. Decent
fetch area to generate significant waves by later Mon and Tue. At
this time, with strong potential of seas above 20 ft later Mon
night, with peak seas briefly 25 to 30 ft late Mon night. Seas and
winds subside on Tue.
Active weather continues for later Tue through Fri, but winds and
seas look to be less intense. Bowen/Rockey
PZ...Gale Warning tonight through early Mon evening on all outer
coastal waters...or from 10 to 60 nm offshore.
Storm Watch for Monday night on all outer coastal waters.
Small Craft Advisory for winds tonight through Monday morning
on all inner waters...or from shore out 10 nm.
Gale Warning from Monday afternoon through Tue morning on all
inner waters...or from shore 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. The area is
commonly referred to as the forecast area.