905
FXUS66 KPQR 102139
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
239 PM PDT Fri May 10 2024

.SYNOPSIS...A 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 throughout the region will shift to onshore flow,
bringing cool yet still above seasonal normal temperatures into
early next week.

&&

.SHORT TERM...Now through Sunday...A positively tilted ridge
will stay overhead early into this weekend. The ridge axis,
running southwest to northeast into southern British Columbia,
will shift south into WA/OR through today as a trough moves
eastward across the Gulf of Alaska. Currently offshore winds
across the Coast Range and Cascades, and northerly winds through
the interior valley. With the combination of the ridge moving
directly overhead and the thermal 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 due to warm
easterly winds from the Gorge. Other inland urban areas, such
as Salem/Corvallis/Eugene, have a 10-20% chance to exceed 90
degrees today and Saturday.

Offshore coastal winds will shift to a northwesterly onshore
flow during the evening as the ridge axis moves past the Coast
Range into the Willamette Valley. This onshore flow could bring
stratus to the coast Saturday morning, thus moderating and
cooling temperatures into Saturday afternoon. With this in mind,
expect coastal temps in the 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 ridge 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!
-JH

.LONG TERM...Monday through Friday...The trough will continue
eastward over the Cascades through early Monday morning. This
will support continued westerly onshore flow, dropping
temperatures across the interior valley into the low 70s, and
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.

WPC cluster analysis has moved more towards a solution favoring
ridging re-developing by the middle of next week. Nearly all
ensemble members display relatively strong and broad ridging by
Wednesday next week, allowing temperatures to climb to the upper
70s in the latter half of the week. Wednesday has good agreement
with this broad ridge remaining over the region, however agreement
lessens Thursday into Friday as there is a 20% chance of a
trough developing and pushing south into the region. This
trough would bring more seasonable temperatures and light rain
showers back to the area, but there is still not enough
model convergence to be certain.
-JH/Batz

&&

.AVIATION...High pressure and dry northeasterly flow aloft will
maintain clear skies and VFR conditions through the day. Along
the coast, onshore northwest winds increasing to 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 or
fog 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. Meanwhile,
thermal trough is gradually shifting farther inland. The pressure
gradient across the coastal waters 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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