563
FXUS66 KPQR 182131
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
231 PM PDT Fri Apr 18 2025

.SYNOPSIS...High pressure and dry conditions continue through
late tonight. 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...Another day of dry and
sunny weather today as the short wave ridge peaks over the
region. Temps expected to peak in the mid to upper 70s inland
and in the low 60s along the coast. Winds inland remain light
and offshore, helping support dry, downslope winds on the west
side of the Cascade crest. The offshore pressure gradient has
weakened along the coast where onshore flow has returned and
helped keep temps lower and dew points higher, around 45-50
degrees. Min RH values are expected to drop into the 20-30%
range (40-50% along the coast) as the dry airmass remains in
place and temps rise well above normal. Not expecting any fire
weather concerns at this time as winds remain below 10 kt and
gusts up 15 kt.

The pattern shifts as we move into the weekend, beginning late
tonight. A series of short wave disturbances are expected to move
across the region shifting the short wave ridge east of the
Cascades. Significant precipitation is not expected through the
weekend but light showers are possible, mainly along the north
OR/south WA coasts and north of the Portland metro. The first trough
could bring, at most, a few hundredths but most locations should see
just a sprinkle. This is 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 begin in the
lower 60s Monday but gradually increase through the middle of the
week toward the low 70s. WPC Cluster guidance shows around a 60%
chance of a slightly more impactful trough moving in next Thursday.
There remains plenty of uncertainty in exact intensity and impacts
with this late week system. -Batz/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...Strong high pressure offshore will maintain northerly
winds across the coastal waters today and through the weekend.
Winds are expected to increase later this afternoon with gusts up
to 20-25 kt through tonight. A weak surface front will drop across
the waters with northerly winds peaking Saturday morning, with
gusts up to 25-30 kt. Additionally, seas around 5 to 7 ft at 13
seconds will build to 8 to 10 ft at 10 seconds tonight,
continuing into Saturday. Will maintain the Small Craft Advisory
through Saturday evening.

Another weak front moves across the waters on Sunday. By Monday,
the thermal trough strengthens over the southern Oregon coast,
increasing the northerly pressure gradients again for early next
week. Seas are expected to persist around 6 to 7 ft. /DH

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 11 PM PDT Saturday for PZZ251>253-
     271>273.
&&

$$

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