298
FXUS66 KPQR 250944
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
244 AM PDT Sat May 25 2024

.SYNOPSIS...Cool and cloudy again today with lingering showers
into the afternoon. Trending warmer and drier on Sunday with the
exception of some light rain chances continuing across the far
north. Temperatures will peak on Monday, then trending back
down through the middle of next week as the next system brings
additional rain chances.

&&

.SHORT TERM...Now through Monday Night...The upper level pattern
this morning features troughing which extends from the BC Coast
to just east of the Oregon Cascades, with scattered showers
continuing across northwest Oregon and southwest Washington in
deep layer northwest flow. This will result in another
seasonably cool and cloudy day across the area as scattered
showers continue into the afternoon and high temperatures only
reach the low 60s across the interior lowlands. Rainfall amounts
will generally be minimal today as the trough shifts east of the
region, with most locations remaining below a tenth of an inch
aside from some locally higher amounts approaching a quarter
inch on favored Cascade slopes. Showers will mostly taper off
by this evening as transient shortwave riding crosses overhead.

Sunday will be characterized by benign zonal flow aloft,
yielding partly cloudy skies and temperatures rebounding to
around 70 in the interior valleys. Expect dry conditions across
most of the area, though a few raindrops can`t be ruled out
across southwest Washington and the far northern Oregon Coast as
a weak disturbance crosses the Washington Coast. The warming
trend continues into Monday with sunnier skies across the area as
a ridge builds east of the Cascades, pushing temperatures well
into the 70s in most locations away from the coast.
Probabilistic guidance continues to indicate a 30 percent
chance for highs to reach 80 degrees in and around the Portland
Metro. A chance for rain returns to coastal areas as early as
Monday night as the next system begins to approach from the
Pacific. /CB

.LONG TERM...Tuesday through Friday...Temperatures begin to
trend back down on Tuesday as the ridge axis shifts farther east
towards the Rockies, increasing the influence of the next upper
level trough encroaching upon the Pacific Northwest from the
Gulf of Alaska. WPC ensemble clusters remain in reasonable
agreement (~70 percent of members) on keeping a troughy pattern
over the region through Thursday, resulting in cool and showery
conditions with temperatures generally in the 60s through most
of next week. Guidance diverges beyond Thursday, which is
reflected by a 20 degree spread between the 25th and 75th
percentile for NBM high temperatures by the end of next week.
/CB

&&

.AVIATION...Widespread VFR conditions throughout. Current chances
of MVFR conditions (from showers) around 20-30% will gradually
decrease to below 10% by 17Z Sat for inland terminals. Coastal
areas will see these chances (20-30%) of MVFR conditions
lingering longer, until around 02-03Z Sun. With building high pressure
quickly scouring out lingering showers, expect predominantly
VFR conditions with chances of MVFR much lower than guidance
suggests. Northwesterly winds along NW Oregon coast and SW
Washington coast will remain just above 10 kt until 23Z Sat.

PDX AND APPROACHES...VFR conditions with west/northwest winds
less than 10 knots through the TAF period. Chances of MVFR CIGS
around 10-20% decreasing below 10% around 18Z Sat. -JH

&&

.MARINE...As the system continues east out of the region, winds
and seas will gradually ease into Saturday morning. Will maintain
the current timing of the Small Craft Advisory, set to expire 11AM
Saturday. Another weak ridge of high pressure brings the return
of benign conditions by Saturday afternoon and these lower
conditions are expected to persist through the start of the
upcoming week. Monday night another system originating from the
Gulf of Alaska will start to move southward and arrive around
Tuesday/Wednesday. An increase of winds and seas across all
waters is expected. -JH

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 11 AM PDT this morning for PZZ210-
     251>253-271>273.
&&

$$

www.weather.gov/portland

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