879
FXUS66 KPQR 270317 AAA
AFDPQR

Area Forecast Discussion UPDATED
National Weather Service Portland OR
815 PM PDT Sun May 26 2024

...EVENING UPDATE, for aviation weather...

.SYNOPSIS...Decaying showers will give way to high pressure on
Monday. Expecting warmer and drier conditions, but could still
see some cloud cover and thus dampening any intense warming.
Another round of rain on Tuesday through Wednesday, with slight
chances for rain on Wednesday along the northern most portions
of the forecast area.

&&

.SHORT TERM...Now through Monday Night...Satellite shows
generally clear skies with a swath of clouds over the north Oregon
and south Washington coast. While the clouds are in place now,  the
clearing skies overnight will allow for ample radiational cooling
overnight. Models are trying to bring in some patchy fog once again,
but with a lack of moisture available, it will be difficult to get
fog for anywhere east of the Coast Range.

Monday will be warmer and drier, though temperatures will still
be under seasonable normals. Inland temperatures will be in the
70s on Monday and in the 50s along the coast...minimal change
from the last previous days. The range of possibilities though
is much more narrow today so confidence is higher that tomorrow
will be a typical springtime day. As the sun begins to set, yet
another weak front will advance towards the coast from the
Pacific bringing along clouds, rain, and cooler temperatures.
At 850 mb around 0 degrees celsius temperatures will fill in
behind the trough causing slow levels to drop and temperatures
to cool at the surface. Overnight temperatures will stay fairly
consistent with normals for this time of year. There are some
chances for rain very early Tuesday morning, but they are
isolated to the coast. -Muessle

.LONG TERM...Tuesday through Saturday...Cool onshore flow
through a majority of the week with rounds of light rain. The
coast, Coast Range, and south Washington Cascades will see the
bulk of the rain on Tuesday and Wednesday, while the Willamette
Valley and Upper Hood River Valley will experience a bit of a
rain shadow effect. Accumulations will be unimpressive. One
shift from the previous forecast is the more widespread slight
chances (15-20%) for thunderstorms on Wednesday. Soundings show
ample convective energy available for some elevated storms, but
unless these showers become more robust or the flow becomes
more southwesterly, storms will be difficult to form. If they
do, it would be isolated singular lightning strikes. Small hail
is not as probable.

Later in the week, conditions have the chance to start drying
out, however, confidence is quite low. Ensemble clusters of the
main long-term models are showing a variety of outcomes,
especially on Saturday. Thursday there is consensus that we
will be on the backside of the trough at 500 mb which will
bring rain to an end and keep more of a neutral flow. Friday is
taking on more of a ridging pattern, but it is looking a bit
flatter than yesterday`s runs. Temperatures have the potentially
to be a few degrees warmer though than what we will see on
Monday. Saturday is a bit more of a mess though as around 25% of
of members are showing ridging, and while the others are more
zonal. Overall, not ready to hang a hat on a drier outcome, but
there is still a chance.                         /Muessle
&&

.AVIATION...Clear skies across the interiro this evening. But, a
weak front offshore is approaching, with increasing mid clouds
across the region overnight. System is quite weak, and as such, will
just bring clouds. Increasing MVFR clouds along the coast tonight,
with those clouds gradually breaking up and lifting to lower VFR by
later Mon am. Farther inland,  will remain VFR, with broken to
clouds (5000 to 6000 ft) later tonight into mid-Mon am. But, those
clouds generally from Salem northward into western WA. Areas to
south and east of Salem likely to remain mostly clear.

PDX AND APPROACHES...VFR with scattered to broken mid-level clouds
rest of this evening. Will see broken to overcast deck at 5000 to
6000 ft from around 09Z to 16Z Monday. Later Mon am, clouds break
apart with VFR and light north winds.
&&

.MARINE...Winds gradually easing this evening, with winds
mostly 10  kt. Not much change through Thursday. Then, another
trough returns that brings some potential for gusts up to 20-25 kt
again. Seas stay at 4 to 6 ft.             /Liu

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.

&&

$$

www.weather.gov/portland

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