578
FXUS66 KPQR 270943
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
240 AM PDT Sat Apr 27 2024

.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...12Z TAFs...Generally VFR conditions, but with the
frontal system approaching the airspace, expect rain to return
along with mixed VFR and MVFR flight conditions. Predominately
MVFR conditions and a 30-40% probability for IFR conditions along
the coast through the TAF period. Predominately VFR conditions for
inland locations with a 25-35% probability for MVFR conditions.
These conditions are expected to persist through the TAF period.
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 will become more westerly with gusts
up to 15 kt along the coast 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, along with a
20-30% probability for MVFR conditions through the TAF period.
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. /42

&&

.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 the
 Columbia Bar and all of the inner coastal waters
 (from shore to 10 nm offshore).

     Small Craft Advisory until 5 PM PDT this afternoon for all
 of the offshore coastal waters (10 to 60 nm offshore).
&&



$$

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