Lake Oswego, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

811
FXUS66 KPQR 302355
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
455 PM PDT Sun Mar 30 2025

&&

.SYNOPSIS...Ridging builds into the area bringing a brief break
in precipitation as well as a slight warming trend today. This
will be short lived as a broad area of low pressure will bring
cool and wet conditions back to the region through the latter
part of the upcoming week. Another shortwave ridge looks to
develop Wednesday evening/Thursday which will bring warm and dry
conditions once again.

&&

.DISCUSSION...Today through Saturday...A pattern change is
currently occurring as troughing begins to build back into the
region, and rain is currently pushing into the region from the
south. This marks the beginning of a few cool and showery days
as an offshore low spins a few rounds of moisture between now
and Thursday.

The initial wave of moisture is currently pushing into the area,
though QPF looks fairly low and rainfall will likely be non-
impactful. Between 5pm Sun to 5pm Monday, only around a 40-50%
chance of lowland rainfall in the Willamette Valley and SW
Washington lowlands to exceed 0.25 inches. At the coast and
Coast Range, slightly higher accumulations closer to 0.5-1.0
inches is expected during this period. Snow levels are currently
around 5000 feet, but will be falling to around 2500-3000 ft by
the end of Sunday night. As such, Cascades snow accumulation
can be expected with this initial wave of moisture. That said,
accumulations are expected to remain below advisory level,
though snow accumulations will continue in the mountains
throughout the week. Initial snow between now and 5pm Monday
looks to be only around 3-4 inches at the central Oregon
Cascades passes, even less at the northern Oregon Cascades.

Easterly gusts through the Columbia Gorge are currently around
30-35 kts, including the Portland metro area. These will
continue to decrease through this evening and tonight, shifting
southerly with gusts up to 10 kts by around midnight tonight.
Afterwards winds remain onshore and fairly weak through
Thursday. Additionally, some weak instability is expected at the
coast beginning this evening, enhanced in part due to
orographic lift. This will produce a 10-15% chance of some weak
isolated thunderstorms tonight at the coast. Monday sees showers
continuing, with thunderstorms at the coast remaining possible
(10-15% chance) through evening hours.

Heading into Monday night, the main low passes south of the area
(near the OR/CA border). Tuesday and Wednesday see generally
unsettled conditions remaining, with weak showers at times.
Accumulations will be generally negligible. Daytime high
temperatures generally around the mid 50s for most inland
locations, closer to the low 50s at the coast.

Thursday through Saturday look to be very similar to each other
as a shortwave ridge builds across the region. Daytime highs
will starting the 50s on Thursday and warming around 5-7 degrees
each day with daytime highs in the upper 60s to low 70s
expected by Saturday. /JLiu/42

&&

.AVIATION...Light rain continues as a frontal boundary lifts
northward across the region. Flying conditions remain largely
VFR at area terminals, with brief MVFR vis possible but low
confidence within heavier rain showers. Latest radar trends
suggest lessening coverage of shower activity after 02-04Z Mon,
although this should have little impact as cigs remain at 4-6
kft with some increase in sct low cloud bases at 2-3 kft given
abundant surface moisture. Following a brief break, renewed
shower activity should arrive after 09-12Z Mon, continuing
through the remainder of the period with increased likelihood of
MVFR cigs across the region.

East winds through the Columbia River Gorge continue at 10-15 kt
occasionally gusting above 20 kt at PDX/TTD, while flow has
turned southeasterly at HIO, and largely out of the south
elsewhere, with persistent speeds around 10 kt and gusts of
15-20 kt within rain showers possible. Expect PDX/TTD to follow
suit and see winds slowly turn out of the southeast to south
through the period, moreso at PDX and less at TTD. Along the
coast at AST/ONP, south to southwest flow may see more frequent
gusts at or above 20 kt.

PDX AND APPROACHES...Prevailing VFR conditions continue into
tonight, with shower coverage decreasing as the frontal boundary
lifts northward after 02-06Z Mon. There remains low chances
(10-20%) for periods of MVFR cigs into tonight, before becoming
more likely after 12Z Mon when shower coverage increases yet
again. Gusty easterly winds will continue ahead of the front,
and then slowly shift out of the southeast to south with
diminishing gusts after 06Z Mon. -Picard

&&

.MARINE...A frontal system is beginning to move across the
coastal waters this afternoon as winds turn from easterly to
more southerly and increase over the next several hours. The
latest high resolution guidance indicates a moderate to high
chance (60-80%) for low-end gale force wind gusts across the
inner and outer waters south of Ocean Park, WA, including the
Columbia River Bar through tonight. Thus, left the Gale Warning
currently in place across all the coastal waters even given the
more marginal nature of the set-up. Winds decrease somewhat by
early Monday morning, though remain elevated with gusts up to 30
kts through Monday afternoon as another low pressure system
approaches the waters. The Small Craft Advisory was extended out
through Monday evening, and may need to be drawn out further
for at least the inner and outer waters south of Cape Falcon
where higher seas and winds may persist.

Expect seas will build again into the low teens late tonight
driven by the marginal gale force winds. These winds will remain
elevated through Monday into Tuesday as a fresh southwesterly
swell arrives, keeping seas up into the 9-14 ft range. Seas then
decrease late Tuesday into Wednesday, leveling out around 5 to
7 ft at 9 seconds by Wednesday afternoon, remaining there for
the middle to end of the week as north to northwesterly flow
resides aloft, keeping winds fairly low, and the prevailing
swell low as well. -Schuldt/HEC

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Gale Warning until 2 AM PDT Monday for PZZ210-251>253-271>273.
     Small Craft Advisory from 2 AM to 11 PM PDT Monday for PZZ210-
     251>253-271>273.
&&

$$

www.weather.gov/portland

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