256
FXUS66 KPQR 101816
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
1115 AM PDT Fri May 10 2024

.SYNOPSIS...A large eastward tilted ridge of high pressure will
remain overhead through early this weekend, bringing dry
weather and rapidly warming temperatures. Inland valley
temperatures are expected to reach the upper 80s to low 90s
today and Saturday - could see some record breaking highs in
urban areas. Saturday night into Sunday, winds will shift from
offshore to onshore flow, bringing cool yet still above seasonal
norm temperatures into early next week.

&&

.SHORT TERM...Now through Sunday...Ridging centered well off the
PNW coast will remain in control into the weekend. The axis runs
southwest to northeast into southern BC but will slip south into
WA/OR through today as a trough moves eastward across the Gulf
of AK. An inverted surface trough axis along the Coast Range
will drift toward the Willamette Valley this afternoon. Winds
remain offshore across the Coast Range and Cascades and
northerly through the interior valley. With the combination of
the ridge moving directly overhead and the surface trough
peaking this afternoon, expect today`s highs to be warmer than
yesterday. There is a 50-80% and a 30-60% chance for
temperatures to exceed 90 degrees today and Saturday,
respectively, however it looks to be mostly focused on the
Portland/Vancouver Metro and areas surrounding. Other inland
urban areas, such as Salem/Corvallis/Eugene, have a 10-20%
chance to exceed 90 degrees today and Saturday.

There is more uncertainty for temperatures at the coast, as some
model guidance is suggesting that the ridge will shift inland
Saturday, leading to onshore flow moderating and cooling
temperatures. As a result, expect upper 70s to low 80s today
with a 50-70% chance to exceed 80 degrees F, decreasing to upper
60s to low 70s on Saturday. Widespread cooling is expected
Sunday as the upper-level shortwave trough moves towards the
coast, weakening the inverted thermal trough overhead and
pushing it eastward.

With such unseasonably warm temperatures for early Spring and
coming out of cold weather, there is no doubt people will visit
rivers, lakes, and the ocean for SW Washington and NW Oregon
this weekend. It is important to remember that rivers and lakes
remain dangerously cold with water temperatures mainly in the
40s. Such temperatures can easily cause cold water shock for
those without proper cold water gear, resulting in an involuntary
gasp of air that can lead to drowning. Be sure to bring a life
vest and be extremely cautious around rivers, especially with
snowmelt causing cold and swift currents! -Batz/JH

.LONG TERM...Monday through Thursday...The trough will continue
eastward over the Cascades on Monday, supporting continued
westerly onshore flow will return, dropping temperatures across
the interior valley into the low 70s and into the upper 50s to
low 60s along the coast. The marine layer will likely remain too
shallow for much in the way of morning cloudiness inland
through Sunday, but the upper ridge may weaken enough for some
low clouds to push into the inland valleys for a few hours
Monday morning. Cannot rule out patchy light drizzle at the
north coast Monday morning as well, especially given the weak
upper-level shortwave progressing overhead providing some added
support just north of our CWA.

WPC cluster analysis is beginning to move more towards a
solution favoring ridging re-developing by the middle of next
week. Around 80% of ensemble members display relatively strong
ridging by Wednesday next week, allowing temperatures to climb
a degree or two through Thursday. Still around a 20% chance of
another trough developing, which would bring more seasonable
temperatures and light rain showers back to the area. -Batz/JH/Schuldt

&&

.AVIATION...High pressure and dry northeasterly flow aloft will
maintain clear skies and VFR conditions through the day. Light
offshore flow along the coast will turn onshore early afternoon
becoming northwest around 10 kt. Light northerly winds expected
through the Willamette Valley. By early Saturday morning, marine
stratus begins to push toward the coast. There is still high
uncertainty when or if the stratus will push onshore at the
coastal terminals, but if it does, would expect IFR to LIFR
conditions there sometime after 10Z Saturday.

PDX AND APPROACHES...VFR as high pressure with clear skies
persists. Generally northwest winds below 8 kt expected. /DH

&&

.MARINE...High pressure still anchored well offshore, as well as
well inland. Meanwhile, thermal trough sits along the coastline.
As such, will maintain light east to northeast winds close to
shore, with north winds as move farther offshore. Still gusty on
the outer waters south of Newport, with north winds gusting 20 to
25 kt. As such, will extend Small Craft Advisory til 8 am today.

Thermal trough will gradually shift farther inland today and
tonight. But, at same time, pressure gradient will stay somewhat
weak. So, will maintain north winds on the waters tonight and Sat,
mostly at 10 to 15 kt, with gusts to 20 kt. Seas stay in the 5 to
7 ft range.

Little change for Sunday into early next week, as high pressure
remains anchored well offshore, and lower pressure well inland. As
such, will maintain north to northwest winds on the coastal
waters. Could see gusts 20 to 25 kt at times in afternoons and
evenings. Seas remain mostly at 5 to 7 ft.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...None.


&&

$$

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