458
FXUS66 KPQR 181742 AAB
AFDPQR

Area Forecast Discussion...UPDATE
National Weather Service Portland OR
1042 AM PDT Fri Apr 18 2025

Updated aviation discussion

.SYNOPSIS...High pressure and dry conditions continue through Friday
night/Saturday morning, with warm temperatures. A series of
disturbances will bring closer to average temperatures for the
weekend and into early next week along with a chance for light
showers.

&&

.DISCUSSION...Now through Thursday...One more day of ridging
conditions as the upper level shortwave ridge moves in and out of the
area over the next 24 hrs. Warm and dry conditions, with Friday`s
temperatures in the mid 70s for most of the Willamette Valley and SW
Washington lowlands; around a 10-40% chance of afternoon temperatures
over 75 degrees. This chance will be higher in and around the
Portland metro area, where the chance is closer to 40-70% chance for
temperatures over 75 degrees. The coast will be slightly cooler,
closer to the mid 60s in the afternoon. Relative humidity values will
be quite dry, with values around 20% RH Friday afternoon throughout
most of the region. Winds will be northerly during daytime hours,
with gusts up to 10-12 kts possible. Winds will gradually be shifting
onshore over the course of Friday night, bringing cooler temperatures
to  come. No fog or frost concerns expected Friday night.

Late Friday night/Saturday morning, a weak shortwave trough pushes
into the region, bringing a few sprinkles during daytime hours
Saturday. Little to no accumulations expected. Temperatures are also
expected to fall to the mid 60s for inland areas, closer to the low
to mid 50 at the coast Saturday afternoon. This will be followed by
another weak trough pushing in on Sunday, bringing around 0.05-0.15"
of rain accumulation between 5am Saturday to 5am Sunday. Afterwards,
a series of weak disturbances pass through the area over much of the
following workweek, though rain accumulation is expected to be fairly
minimal during this time. Daytime high temperatures in the upper 60s
throughout this period. WPC Cluster guidance shows around a 60%
chance of a slightly more impactful trough moving in next Thursday.
/JLiu

&&

.AVIATION...An upper ridge of high pressure remains over the
region today with mostly clear skies and VFR conditions persisting
through at least 00z. Flow turns back onshore this evening as a
weak front approaches, likely pushing marine stratus onto the
coast by 02-03z Saturday. Will also see increasing mid to high
level clouds inland. CIGs along the coast will likely fall to
MVFR, along with a 70-80% chance of IFR cigs between 04-12z
Saturday. Northwest winds along the coast are expected to increase
this afternoon with gusts to around 20 kt.

PDX AND APPROACHES...VFR through the TAF period. Increasing clouds
later tonight with CIGs lowering to around 4000-6000 ft after 12z
Saturday. Northwest winds expected around 4-8 kt, strongest in
the afternoon. /DH

&&

.MARINE...Pressure gradients are weakening early Friday morning as
a weak surface front moves through the eastern Pacific. Northerly
winds will be around 8-12 kts with gusts less than 20 kts except
for some isolated stronger winds with gusts to 20-25 kts in
PZZ273. The front approaches the waters Friday afternoon, moving
through the waters Saturday. Northwesterly winds strengthen again
with gusts to 25-30 kts through Saturday evening. Additionally,
seas around 5-7 ft at 13 seconds through Friday evening will build
to 7-9 ft at 12 seconds late Friday night, continuing through
Saturday. A Small Craft Advisory has been issued for 2 PM Friday
afternoon through 11 PM Saturday night. -HEC

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory from 2 PM this afternoon to 11 PM PDT
     Saturday for PZZ251>253-271>273.

&&

$$

www.weather.gov/portland

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