227
FXUS66 KPQR 170335 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
835 PM PDT Sun Jun 16 2024

Updated aviation discussion and short term discussion.

.SYNOPSIS...Low pressure maintains cool and showery conditions
today, with a chance of thunderstorms across much of the area
this afternoon and evening. A few showers linger into Monday
then much warmer and drier weather returns Tuesday through the
end of next week.

&&

.UPDATE...Sunday evening...Radar and surface weather observations
across northwest OR and southwest WA as of 830 PM Sunday depicted
decreasing showery activity. While scattered thunderstorms did
develop between 3-7 PM, have seen little to no lightning activity
since then as diurnal heating wanes. Given the surface-based nature
of these storms, do not expect anymore thunderstorm activity for the
rest of the night. That said, stronger showers Sunday evening will
produce brief heavy downpours with rainfall rates up to 0.25 in/hr.
-TK

&&

.SHORT TERM...Sunday Afternoon through Tuesday...Radar imagery
as of 2 PM PST shows showers pushing into western Oregon and SW
Washington just east of the Coast Range and Willapa Hills. The
center of the positively-tilted upper level trough that has
been impacting the PacNW this weekend has moved into southern
Washington today with the axis slowly approaching the coast from
the eastern Pacific. Instability is building as the trough is
impacting the region with SPC mesoanalysis indicating 250+ J/kg
MUCAPE across the majority of NW Oregon and SW Washington with
an area of 500+ J/kg MUCAPE west of the Coast Range. CAPE will
continue to increase over the next few hours with thunderstorm
chances into the early evening hours. Expect heavy rain, some
lightning, small hail, and locally gusty winds with any strong
cell or thunderstorm that forms. Temperatures today will be
similar to yesterday under the influence of the trough with
inland highs in the mid to upper 60s and 50s along the coast.
Low temperatures tomorrow morning will be on the cooler side
again with 40s in the lowlands.

The trough will finally move through eastern Oregon into the
northern Rockies Monday. A few showers are possible throughout
the day, mainly over the higher terrain, with temperatures
similar or a few degrees warmer than today. By Tuesday,
ensembles remain in good agreement that troughing begins
weakening, bringing the return of dry weather everywhere with
temperatures warming back to near normal for mid June, low 70s
for the interior lowlands and 60s for the coast. -HEC

.LONG TERM...Wednesday through Sunday...A significant warming
trend remains on track for Wednesday through Friday of this
week. Ensemble guidance continues indicating a Rex Block type
pattern emerging by Wednesday over the West with an upper level
ridge over western Canada and a trough over California.
Temperatures are forecast to rise into the 80s on Wednesday,
with Thursday and Friday peaking as the warmest days. NBM
indicates high confidence (80-95% chance) of temperatures over
80 degrees through Saturday for the interior lowlands.
Probabilities for temperatures reaching 90 degrees or higher
have increased for Thursday and Friday. On Thursday, there`s now a
50-60% chance for most of the Willamette Valley from Salem north
and 20-45% chance south of Salem. Probabilities have also
increased for 95+ degrees with a 20-30% probability for the
general Portland/Vancouver metro area.

WPC 500mb clusters continue to indicate an approaching trough
will push the upper ridge east into the central US with heights
lowering over the PacNW on Saturday, which could lower
temperatures by a few degrees to the low to mid 80s. By Sunday,
clusters show enough agreement that heights will lower enough to
bring temperatures back to near normal in the 70s. However,
there is enough uncertainty in the specifics of the trough along
with amount of moisture on whether any precipitation will be
possible. Current NBM forecast has around a 15-20% probability
for the coast and higher elevations, though accumulation seems
to be limited at this time. -HEC

&&

.AVIATION...Widespread rain showers continuing to diminish through
06Z Monday across the airspace. However, isolated showers will
persist through at least 15Z Monday over the Cascades and Coast
ranges. Otherwise, generally VFR conditions but could see some
backbuilding clouds moving eastward off the Cascades, resulting
in a 20%-30% probability of MVFR CIGs between 12Z-18Z Monday for
inland locations.

The coast will have around a 50-60% probability for MVFR
conditions starting around 06Z-08Z Monday at KAST and spreading
southward towards KONP through 10Z-12Z Monday. Through the same
time period (06Z-12Z Monday), the coast will also have a 20%-30%
probability for IFR/LIFR conditions.

Starting around 18Z-20Z Monday, any lowered conditions will start
to improve to VFR across the airspace which is expected to
persist through at least 06Z Tuesday.

PDX AND APPROACHES...Showers continue to diminish with VFR
conditions. 20% probability of MVFR CIGs between 12Z-18Z Monday
with backbuilding eastward off the Cascades. Any lowered flight
conditions will start to dissipate around 18Z Monday with VFR
expected to dominate through at least 06Z Tuesday. /42

&&

.MARINE...Seas around 5 to 7 ft at 9 to 11 seconds for the near
future. Northwesterly winds currently strengthening to just under
Small Craft Advisory criteria this evening, lasting through the
night. A few gusts above SCA criteria may be possible at times.
Next chance at more impactful conditions will be Tuesday night,
but uncertainty still remains high as it looks to be another
marginal wind-driven event. Looking forward, marginal SCA winds
look possible from Tuesday evening onward, with breezy marginal
winds possible until at least the weekend. -JH/JLiu

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

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