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000
FXUS66 KPQR 140408 AAA
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
908 PM PDT Sat Apr 13 2024

Updated aviation discussion

.SYNOPSIS...
Light showers impact areas to the south through the night. A
few afternoon/evening non-severe thunderstorms are developing
along the southern Oregon Cascades, with impacts mainly in
eastern Lane County. Mild and less showery weather expected for
Sunday, then cooler and wetter into the beginning of next week
as another system approaches from the northwest.

&&

.SHORT TERM...THROUGH SUNDAY NIGHT...In the northern half of the
CWA (north of Salem), dry conditions with light cloud cover are
expected. Temperatures today will continue the warm streak, with
the northern Willamette Valley reaching into the low 70s, and
the coast into the low 60s. Further south, the edges of a system
passing through California clip up, and with sufficient daylight
heating, thunderstorms are developing mostly over the southern
Oregon Cascades and Cascade foothills, where orographic lift
compensates for relatively weak CAPE values of 150-250 J/kg.
Showers continue as well, though QPF values through Sunday
morning look fairly low: only a 20-30% chance of QPF during
this period exceeding 0.5". Any thunderstorms aren`t expected to
be severe, and lightning and isolated wind gusts up to 35mph
should be the only concerns.

Showers end everywhere but the southern Cascades over Saturday
night, and defined onshore flow returns to the area on Sunday.
Temperatures cool slightly as a result, with Willamette Valley
temperatures back into the mid to upper 60s and coastal
temperatures returning to the mid 50s. The next system begins
moving in near the end of Sunday night from the north, with very
light QPF values, under 0.10" through Monday. /JLiu

.LONG TERM...Monday through Friday...A few light rain showers
are expected throughout Monday and Tuesday as another low passes
north of us, aimed moreso at the northern Rockies, but QPF looks
minimal. Temperatures drop to below climatological averages,
into the upper 50s both days.

WPC ensemble clusters still show some variation on the
specifics of the pattern beyond Tuesday, but all generally
depict a warming and drying trend across the area as the trough
departs into the central CONUS and a ridge of high pressure
builds either over the eastern Pacific or directly over the
Pacific Northwest. This is supported by nearly all individual
ensemble members showing dry weather from Wednesday through
Friday of next week, with ensemble guidance showing temperatures
trending well into the 70s in the Willamette Valley Friday.

&&

.AVIATION...Southeasterly flow aloft turns easterly overnight, and
northeasterly by Sunday morning, as the upper level low near the
central California coast moves inland. Mid to high level clouds
from thunderstorms east of the Cascades today continues to spread
across the forecast area while light shower activity will likely
continue overnight across parts of the Oregon Cascades and
southern Willamette Valley through at least 12Z Sunday.
Predominately VFR expected through the period, except at the coast
where marine stratus is likely to return, bringing low MVFR to
IFR conditions tonight into Sun morning. There`s also increasing
chances (30-50%) of lower flight conditions across the southern
Willamette Valley, including KEUG, after 08Z Sunday.

PDX AND APPROACHES...Expect VFR conditions with high clouds
through the period. Southerly winds should eventually turn back
northwest 4-6 kt tonight. /DH

&&

.MARINE...The region continues to be under the influence of a
cut-off low situated off the California coastline today keeping
northerly winds in place across the waters. Expect wind gusts in
the 20-30 knot range to persist through the rest of the weekend
as the aforementioned low slowly progresses eastward. A NW swell
at 7-10 feet with a period of 9-10 seconds persists. A Small
Craft Advisory is in effect for winds and seas through Sunday
evening for all zones. Surface high pressure builds over the
Pacific Ocean Monday into midweek with widespread winds decreasing
below Small Craft conditions (gusts greater than 21 kts) and seas
decreasing to 6-8 kts with period increasing to 10-12 seconds by
Monday morning, persisting into midweek. Guidance suggests
Thursday into Friday a thermal trough could build over northern
California and southern Oregon with high pressure remaining over
the Eastern Pacific, which could bring elevated northeasterly
winds to the waters. -HEC

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 11 PM PDT Sunday for PZZ210-251>253-
     271>273.
&&

$$

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