467
FXUS66 KPQR 302310
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
410 PM PDT Thu May 30 2024

.SYNOPSIS..Warm and dry weather through Friday. A weakening front
pushes across the area on Saturday, which will result in a slight
cooling trend but generally remaining dry. Then, a much wetter
system associated with what remains of a tropical system is expected
Sunday through Monday. Warm and dry weather returns for the middle
of next week.

&&

.SHORT TERM...Tonight through Saturday night...Pleasant weather
continues as we flip the calendar from May to June. Weak upper level
ridging over the eastern Pacific will push east across the Pacific
NW on Friday. Temperatures warm Friday afternoon into the upper 70s
to near 80 degrees inland, while northerly winds turning back
onshore will maintain temperatures in the 60s at the coast. Breezy
northerly winds continue through the Willamette Valley, becoming
more westerly as onshore push begins.

Increasing clouds on Saturday as a weak shortwave trough pushes a
weakening front towards the area. Most areas are expected to remain
dry, with a few light showers possible at northern coastal areas and
in the Cascades. Temperatures return to near normal for June 1st
with highs expected into the lower to mid 70s inland. Winds remain
generally onshore through Saturday. /DH

.LONG TERM...Sunday through Thursday...Rain is expected to return
Sunday as a frontal system with an associated atmospheric river
pushes into the Pacific NW. The initial warm front will bring
generally steady, light rain through Saturday afternoon while
pushing snow levels above 9,000-10,000 feet. Zonal flow turns more
southwesterly as an upper shortwave trough approaches the region
late Sunday. Precipitable water values peak around 1.4-1.5 Sunday
evening through Sunday night while IVT values increase to around 500
to 750 kg/ms. Strong dynamics as nose of a strong upper level jet
pushes into Oregon. This will likely bring more moderate rainfall
through Sunday night into early Monday. Showers then follow behind
the front by Monday afternoon with a 15-20% chance of thunderstorms
Monday afternoon. Latest QPF from WPC and NBM suggest 36-hour
rainfall amounts at the coast of around 1.5 to 2.5 inches, 2 to 4
inches for the Coastal mountains as well as the Cascades and Cascade
foothills. Rainfall amounts are likely around 1.0 to 1.5 inches
across the inland valleys. Even with all this rain, not expecting
river flooding (less than 5% chance) or many hydro impacts. Will
need to continue to monitor for higher rainfall rates especially
near the Columbia River Gorge, although currently not expected to
exceed 0.25 inch per hour.

Another system then approaches on Tuesday, although there is
increased uncertainty as to how far south the front will drop.
Therefore will maintain a slight chance (10-20%) of rain from the
central OR coast/southern Willamette Valley to likely rain (60-70%)
across the northern coast into southwest WA. By Wednesday, high
pressure is expected to build offshore. Cluster analysis shows
varying degrees of strength of an upper level ridge over the western
US. A warming trend is likely by mid-week through the end of the
week, with highs most likely in the 80s by Thursday. /DH

&&

.AVIATION...Prevailing VFR conditions across the area through the
forecast period as high pressure builds bringing northerly winds
aloft and at the surface. North winds increase after 18-21z
Thursday with most locations around 10-12 kt. The southern
Willamette Valley, including KEUG, will see winds 10-15 kt with
gusts up to 25 kt, and coastal locations around and south of KTMK
will see winds 15-20 kts with gusts to 30 kts. Winds decrease from
00-05Z Friday.

PDX AND APPROACHES...Expect VFR conditions through the TAF period.
North winds increasing to 10-12 kts through around 05Z Friday.
Otherwise, expect light winds below 10 kts. -HEC

&&

.MARINE...Weak high pressure continues to build across the the
waters today into tonight, slowly retreating west into the
offshore waters Friday. This will lead to increasing northerly
winds off of the central Oregon coast this afternoon and evening.
There is 60-80% chance that winds gust to 25 kt generally from
Tillamook and south with > 90% chance of winds exceeding 20 kt.
Winds will decrease for a few hours Friday morning before
increasing to gusts up to 21 kts (80-90+ % chance) Friday
afternoon and evening. A Small Craft Advisory remains in effect
for zones PZZ273, PZZ272, PZZ253, and PZZ252 through Friday
evening.

A weak front is expected to move through the waters on Saturday,
shifting winds westerly to southwesterly. A more organized and
stronger storm system will move into the northeast Pacific Sunday
shifting winds southerly. Small Craft Wind gusts are likely with
90+% chance of gusts exceeding 21 kts and 50-60% chance of gusts
reaching 30 kts. There`s also a 50-70% chance of a brief period of
Gale Force winds of 35 kts Sunday afternoon or evening. -HEC

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 11 PM PDT Friday for PZZ252-272.

     Small Craft Advisory until 11 PM PDT Friday for PZZ253-273.

&&

$$

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