Oregon City, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

454
FXUS66 KPQR 221318 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
451 AM PST Sat Feb 22 2025

.SYNOPSIS...Active weather through early next week as a
moderate to strong atmospheric river and multiple frontal
systems bring moderate to heavy rain and periods of strong winds
to the area today through Monday. Greatest flood concerns for
coastal rivers, with ponding of water as the main concern
inland. Quieter conditions expected mid to late next week.

&&

.SHORT TERM...Now through Monday Night...Radar imagery shows light
rain associated with a weak warm front spreading across
northwest Oregon and southwest Washington as of early Saturday
morning as an atmospheric river begins to take aim on the
Pacific Northwest. Rainfall amounts have been limited to less
than a tenth of an inch in most locations overnight, but a few
locations on the central Oregon Coast have reported 6 hour
rainfall totals exceeding a quarter inch. Shower activity will
remain light and spotty through much of the day as the warm
front departs the area, but precipitation will increase in
intensity later in the afternoon with the arrival of a trailing
cold front as precipitable water values surge above one inch.
Expect rainfall totals from this evening through Sunday morning
to range from 1.50-2.00 inches for coastal areas and the higher
terrain, with amounts approaching 1 inch in the interior
lowlands. The period of heaviest rainfall looks to occur during
the day on Sunday as PWAT values remain above 1 inch and IVT
values peak in the 500-750 kg/m/s range along the Oregon Coast.
Rainfall Sunday afternoon will also be aided by forcing from a
shortwave trough embedded in southwest flow aloft, along with an
associated surface frontal boundary. Model QPF during the day
on Sunday depicts an additional 1-2 inches of rain for the coast
and higher terrain, with another 0.75-1.00" for the interior
valleys through Sunday evening. Sunday night will bring a
relative lull in precipitation between systems as transient
upper level ridging passes overhead. The last in the series of
frontal systems will then bring one more shot of moderate to
heavy rain to the area on Monday, this time focused mainly along
coastal areas. Those coastal areas could see another 1-2 inches
of rain through Monday night, with an additional 0.50-0.75"
looking more likely for area east of the Coast Range. The
period of heavier precipitation will come to an end as an upper
level trough crosses the region Monday night. Refer to the
Hydrology section below for details regarding potential flood
impacts from this event.

Wind will be the other main forecast concern over the next few
days as the series of seasonably strong frontal systems crosses
the region. The first round of wind will come later this
afternoon with the arrival of the cold front. Generally expect
winds with this front to gust to 40-50 mph along the coast. It
would not be out of the question to see a stray gust or two to
60 mph this afternoon on beaches and headlands, but do not
expect these conditions to be widespread enough to warrant any
wind headlines for the coast today. Gusty south winds will also
spread inland to the Willamette Valley this afternoon and
evening. Expect winds generally in the 25-35 mph range with a
few gusts as high as 40 mph this afternoon and early evening.
Sunday`s system looks to bring similar magnitude winds, with
another round of 40-50 mph along the coast and 25-35 mph winds
in the inland valleys. Monday`s system looks to bring perhaps
the strongest winds of the event as models show relatively good
agreement in a strong surface low bottoming out around 980 mb as
it passes offshore during the day on Monday while tracking
towards Vancouver Island. NBM probability for 60 mph winds
increases to approximately 40 percent along the coast late
Monday morning/afternoon. Do not quite have the confidence for
a High Wind Watch on the coast at this time, but that may be a
consideration in future forecast packages. Would expect the
strongest winds to mostly be confined to beaches and headlands,
with gusts more likely to be in the 40-50 mph range for inland
coastal communities. Similarly, Monday`s system will present
the best chance for advisory level winds in the inland valleys
as NBM probs for 45 mph gusts increase to 15-30% from Portland
to Eugene during the day on Monday. Will need to pay close
attention to how models evolve with respect to the track of the
surface low as a track closer to the coast will increase the
potential for stronger winds across the area. Will also need to
consider the impacts from saturated soils as that could
contribute to the potential for downed weakened or dead trees
over time. /CB

.LONG TERM...Tuesday through Friday...Showers will be winding
down across the area on Tuesday in the wake of the atmospheric
river as high pressure begins to build in behind the departing
trough. Could see some minor snow accumulations return tot e
Cascade passes Monday night through early Tuesday as the
passing trough drops snow levels down to around 4000 feet.
Beyond Tuesday, WPC ensemble clusters strongly favor a ridgier
pattern developing over the Pacific Northwest and western CONUS
through much of next week, promoting a warmer and drier pattern
across the region. This is reflected in the bulk of individual
ensemble members which keep the area dry from Wednesday through
Friday of next week. Likewise, the NBM mean depicts around a 75%
chance for high temperatures to surpass 60 degrees in the
Willamette Valley during the middle to latter part of next
week. /CB

&&

.AVIATION...Observations as of 11Z is showing light rain slowly
moving eastward across the region. This will result in the
widespread VFR between FL030 and FL050 to slowly lower towards a
mixture of low-end VFR/high-end MVFR with bouncing cigs between
FL025 and FL045. Look for these conditions to start manifesting
around 15Z-18Z Saturday. Coastal locations will are expected to
improve towards MVFR as precipitation spreads through 14Z-16Z
Saturday. For the whole airspace, expect conditions to deteriorate
towards IFR/LIFR starting around 20Z-22Z for coastal locations and
towards predominately MVFR for inland locations starting around
00Z-03Z Sunday. Precipitation is expected to persist through the
TAF period.

Surface winds will generally be southerly for most terminals,
strongest at the coast with gusts up to 40 kt and up to 30 kt for
inland locations starting around 20Z Saturday. Also, strong upper
level winds are also expected and is resulting in a LLWS threat
via speed shear for the majority of the airspace starting around
20Z Saturday.

PDX AND APPROACHES...VFR with FL030 to FL050 that will lower to a
mixture of low-end VFR/high-end MVFR with bouncing cigs between
FL025 and FL045 as precipitation spreads from west to east. Southerly
gusts up to 30 kt starting around 20Z Saturday along with a LLWS
threat via speed shear starting around the same time. /42

&&

.MARINE...A series of systems will lead to active weather across
the waters through early next week. The first in a series of
systems will bring about widespread southerly Gales with gusts
up to 45 kt through tonight, along with high probability for
isolated gusts up to 55 kt. The next system on Sunday will
continue the southerly flow pattern, but is expected to be
slightly weaker with SCA conditions with gusts up to 30 kt. The
third and currently strongest system looks to maintain the
southerly flow and bring Storm Force gusts up to 55 kt across
all waters.

In addition to the increasing winds, seas will behave in a
similar manner. Current buoy observations are showing seas in the
13-15 ft range which is expected to persist through today. Seas
will briefly subside on Sunday towards 10-12 feet, but this will
be short lived as the aforementioned system on Monday/Tuesday
will bring a very robust southerly swell, that when combined with
the Storm Force winds will result in seas building towards 20-26
ft with peak seas likely around 26-28 ft Monday evening through
early Tuesday morning.

Given the active pattern there are multiple hazards that have been
issued. A Hazardous Seas Warning will persist through very early
this morning. A Gale Warning starting early this morning through
Sunday evening. A Small Craft Advisory Sunday evening through
Monday morning. Storm Watch starting Monday morning through Monday
evening. /42

&&

.HYDROLOGY...A fairly long duration atmospheric river event will
be enhanced by several systems crossing the region today
through Monday, leading to multiple periods of moderate to
heavy rain across the area this weekend through the early part
of next week. In all, models have remained fairly consistent in
depicting 72 hour rainfall amounts from this morning through
Tuesday morning of 4-6 inches in along the coast and in the
adjacent higher terrain, with 2-3 inches likely in the interior
valleys. Amounts of 7+ inches are not out of the question in
orographically favored parts of the Oregon Coast Range as well
as the High Cascades. Rainfall looks to be fairly evenly
distributed each day through Monday, with 1-2 inches of rain
along the coast and in the mountains and up to one inch for the
interior lowlands each period. This will certainly produce rises
on area rivers. Expect to see the largest responses on some of
the flashier rivers in the Coast Range, including the Grays,
Wilson, and Siletz Rivers. Each of these locations show anywhere
from a 20-40% chance of reaching minor flood stage late Sunday
into early Monday, with the Wilson River at Tillamook notable
showing a 20% chance to reach moderate flood stage in the most
recent model run. Other coastal rivers show generally a 5-10
percent chance of reaching flood stage. Meanwhile, several
slower responding rivers on the other side of the Coast Range
are forecast to reach action stage Monday into Tuesday, but no
inland rivers are currently forecast to reach flood stage. The
primary impacts in lowlands will likely be related to ponding of
water on roadways and poor drainage in low lying areas. Do not
currently expect any widespread debris flow or flash flooding
concerns as hourly rainfall rates look to max around around a
quarter to perhaps a half inch, and therefore should remain well
below thresholds on area burn scars through the duration of the
event. Continue to monitor the forecast closely as relatively
minor changes in forecast rainfall amounts could have
significant implications on potential for potential river and
areal flood concerns in the coming days. /CB

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Hazardous Seas Warning until 7 AM PST this morning for PZZ210-
     251>253-271>273.

     Gale Warning from 7 AM this morning to 7 PM PST Sunday for
     PZZ210-251>253-272-273.

     Small Craft Advisory from 7 PM Sunday to 10 AM PST Monday for
     PZZ210-251>253-272-273.

     Storm Watch from Monday morning through late Monday night for
     PZZ210-251>253-271>273.

     Gale Warning from 7 AM this morning to 10 PM PST this evening
     for PZZ271.

     Small Craft Advisory from 10 PM this evening to 10 AM PST
     Monday for PZZ271.
&&

$$

www.weather.gov/portland

Interact with us via social media:
www.facebook.com/NWSPortland
x.com/NWSPortland