FXUS66 KPQR 162113 AAA
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
212 PM PDT Mon Mar 16 2026

.SYNOPSIS...Upper level ridging will bring warmer spring-like
temperatures and light winds through at least Thursday with high
temperatures mainly in the 60s, except lower 70s for inland valleys
in Lane County and mid 50s to lower 60s over southwest WA and the
north Oregon coast. Mainly dry conditions will persist each day south
of a line extending from Lincoln City to McMinnville to Troutdale to
Stevenson, while locations north of that line will see occasional
rain Monday night through Thursday, especially in Pacific County and
along the north Oregon coast. Trending a touch cooler on Friday with
a 30-60% chance of rain showers, except 60-80% along the coast,
coastal mountains, and south WA/north OR Cascades. The forecast
becomes more uncertain over the weekend in regards to temperatures
and precipitation amounts.

&&

.DISCUSSION...Now through Sunday night...There are no signs of any
high impact weather this week across northwest Oregon and southwest
Washington. The forecast remains highlighted by upper level ridging
with relatively warm spring-like temperatures, light winds, and
mainly dry conditions across most of northwest Oregon now through at
least Thursday. However, rain is likely at times (>60% chance) Monday
night through Thursday over northern portions of the forecast area,
particularly to the north of a line extending from Lincoln City to
McMinnville to Troutdale to Stevenson. Rain will be most persistent
over Pacific County and the far north Oregon coast; these areas have
forecast rain totals ranging between 1.25-2.50 inches from 11 PM PDT
Monday through 5 AM PDT Friday. Since these rain amounts are extended
over a prolonged period of time with unimpressive hourly rain rates,
flooding is not a concern. Confidence is high flooding will not be a
concern even if the worst case scenario verified, as the NBM 90th
percentile for 72-hour rain amounts ending at 5 AM PDT Friday is not
high enough to suggest flooding will occur (max amounts up to 3.0
inches, rather than 1.25-2.50 inches like the official deterministic
forecast suggests). Nevertheless, these areas will be much wetter
than the rest of southwest Washington and northwest Oregon this week,
and will therefore experience relatively cooler temperatures. Expect
high temperatures mainly in the mid to upper 60s across the lowlands
each day through Thursday or Friday, except lower 70s for inland
valleys in Lane County and mid 50s to lower 60s over southwest WA and
the north Oregon coast.

The forecast becomes more uncertain over the weekend as model
ensemble guidance begins to differ on how deamplified the upper level
ridge over the western CONUS will become. WPC's cluster analysis for
500 mb heights and anomalies highlights this uncertainty well,
showing around a 20-40% chance the ridge will deamplify enough to
result in a transition from southwest flow aloft to nearly zonal
flow, and a 60-80% chance the ridge will remain amplified enough to
result in continued southwest flow aloft. If the ridge does deamplify
enough for zonal flow aloft to develop, expect relatively cooler
temperatures will occasional light rain showers. If the ridge
remains amplified with continued southwest flow aloft, expect mainly
dry conditions with warmer temperatures. The NBM 10-90th percentile
for high temperatures reflects this uncertainty well, ranging from
the lower 50s to mid 70s on Saturday and from the lower 50s to lower
60s on Sunday. Large model spread is evident for low temperatures
too, ranging from the lower 30s to mid 50s Saturday night/Sunday
morning. Regardless of the outcome, confidence is high there will be
no high impact weather to worry about. NBM PoPs seem to reflect the
most likely outcome of continued southwest flow aloft, only peaking
between 20-40% west of the Cascades on Saturday and Sunday and 40-50%
in the Cascades. -23

&&

.AVIATION...A broad upper level ridge with mid-level moisture will
maintain west to northwest flow aloft along with mid to high level
clouds streaming across the area. Expect widespread VFR conditions
to continue through the period at most terminals. Conditions along
the coast may drop to MVFR with a 30-50% chance of MVFR CIGs any
given hour through the evening. Probabilities increase tonight as
a weak front sags towards the area. MVFR conditions have a 70% or
greater chance of occurring and a 30-50% of IFR conditions.
Southerly winds 5-10 kt expected through the TAF period.

KPDX AND APPROACHES...Mainly VFR conditions expected with
southerly winds 5-10 kts becoming light and variable overnight.
Light rain showers move in late tonight along with a low (10-20%)
chance of MVFR conditions. -19

&&

.MARINE...Southerly winds across all waters expected through the
middle of the week. Wind gusts up to 25 kt will be possible
through Tuesday as a cold front sags southward toward the
northern Oregon and southern Washington coasts. Small Craft gusts
will be possible from Cape Foulweather to Cape Shoalwater,
including the Columbia River Bar. Small Craft Advisories are out
through 4 am Wednesday. Seas will build tonight to between 8 and
10 feet at 10 to 12 seconds as winds increase and a southwesterly
to westerly swell moves into the waters.

Conditions improve by the middle of the week. Another weak front
may pass through the region Thursday, bringing a chance (30%) for
low end Small Craft gusts. -19

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory from 5 PM this afternoon to 5 AM PDT
     Wednesday for PZZ210-251-252-272.

     Small Craft Advisory until 5 AM PDT Wednesday for PZZ271.
&&

$$

www.weather.gov/portland

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