073
FXUS66 KPQR 271936
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
1236 PM PDT Sat Apr 27 2024

Updated aviation discussion.

.SYNOPSIS...Another front will push across the region today,
with rain this morning into the afternoon, then showers. Showers
will continue into early next week. May have a day or two break
(Wed into Thu), but more precipitation arrives to start next
weekend.

&&

.SHORT TERM...(Today through Monday)...As of 2 am, still have
some lingering showers, mainly over the Cascades. Next front is
offshore, and fast approaching. As such, will see rain spread
back to the coast by daybreak, with rain spreading inland this
morning. This front is moving at a decent pace, will will push
onshore this afternoon, racing to the Cascades by late
afternoon/early evening. Will trend forecasts a such, the rain
transitioning to showers behind the front. Overall rainfall not
all that much, with generally 0.25 to 0.50 inch along the coast
into the Coast Range/Willapa Hills, and parts of the Cascades
from Mt Jefferson northward. Bit less rain for inland valleys,
with 0.10 to 0.25 inch expected.

Once the front passes, will have cooler air aloft push inland. This
will maintain showers tonight into Sunday. Lapse rates do steepen
just a tad, enough such that with any warming that comes with the
breaks in the clouds, could see an isolated thunderstorm. Not all
that sold on the idea, but will maintain a slight chance for areas
along the coast, as as inland for Sunday afternoon/evening north of a
Tillamook to Estacada line.

Another fast moving upper level system will push off the Pac into the
region Sunday night. This will enhance the showers, with even a
period of steady rain for a few hours Sun night. As this disturbance
passes, snow levels will drop from 4000-4500 ft on Sunday down to
2500-3000 ft Sunday night. Could see another 2 to 6 inches of snow
across the Cascades at that time. But, with more showery pattern by
that time, accumulations across the higher terrain will be more
random and non-uniform. But, with this being a late season drop of
snow levels, may need to issue a winter weather advisory for the
Cascades for Sunday night into early Monday, but will let day shift
(or next few shifts) re-evaluate that scenario.      /Rockey

.LONG TERM...(Tuesday through Thursday)...No changes. Overall
confidence is low to moderate the pattern stays rather progressive
into late next week - deterministic and ensemble guidance struggle
resolving the longitudinal placement of ridge/trough features
going forward. Showers are expected to linger on Tuesday as snow
levels hold somewhere between 2500-3500ft. Wednesday guidance
has continued to trend a little drier nudging a larger scale
upper-level low further north while a transient ridge glides
over the region. Out of all the ensemble solutions available,
this scenario is present in roughly 60% of them in addition to
the latest deterministic ECMWF and GFS. Past this point model
uncertainty becomes truly significant with nearly a 50/50 split
between maintaining a ridge feature overhead or bringing a
potent trough into the region by Thursday. Hopefully in the
coming forecast runs guidance begins to show better agreement
resolving the pattern mid to late week. Current confidence in
the forecast by Thursday is low.    /Schuldt

&&

.AVIATION...Scattered showers continue across NW Oregon and SW
Washington through Sunday, bringing lowered ceilings and
visibilities at times. Along the coast and higher terrain,
predominately MVFR conditions with local IFR in heavier showers
expected through the period. Elsewhere, including lowland valleys,
ceilings expected to hover right around the VFR/MVFR threshold,
generally bouncing around between 2500-3500 ft through around 07z
Sunday. Expect lower ceilings and visibilities in passing
showers.

Southerly winds across the airspace through around 00Z Sunday
with gusts up to 25 kt along the coast and up to 20 kt for inland
locations. Afterwards, winds along the coast will become more
westerly with gusts up to 15 kt as southerly winds persist inland
with gusts up to 10 kt through the remainder of the TAF period.

Notes: The ASOS at KTTD is only available via the dial in option.
The AWOS at KMMV is still out of commission. There is no
estimated time of repair.

PDX AND APPROACHES...Predominately VFR with rain showers. Ceilings
will hover around 3500-4500 ft through the TAF period along with
a 60-80% probability for MVFR conditions from 21z Saturday through
05z Sunday. Southerly winds with gusts up to 20 kt through around
00Z Sunday. Afterwards, winds will subside with gusts up to 10 kt
through the remainder of the TAF period. -HEC

&&

.MARINE...Elevated conditions persist through today, resulting
in steep and choppy seas along with gusty southwesterly winds
with gusts up to 30 kt. Therefore, have adjusted the timing of
the current Small Craft Advisories to reflect this as conditions
will start to subside by Saturday afternoon as winds become
more westerly. However, this will be somewhat short lived as the
next system is expected to start impacting the waters Sunday
and will bring a return to Small Craft winds and seas that are
expected to persist across as waters through the start of the
upcoming week. /42

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 8 PM PDT this evening for PZZ210-
     251>253.
     Small Craft Advisory until 5 PM PDT this afternoon for
     PZZ271>273.
&&

$$

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