National Weather Service Area Forecast Discussion for Long Beach, WA USA

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Area Forecast Discussion
National Weather Service Portland, OR or
346 am pdt tue apr 29 2025

.synopsis...light rain will spread across the area this morning,
tapering off across most locations by early afternoon.
conditions trend warmer and drier for wednesday, with inland
temperatures likely rising into the 80s on thursday. another
trough brings more mild and wetter weather friday into the
weekend.

&&

.short term...now through thursday night...radar shows light
rain starting to push into the willamette valley as of 3 am
tuesday as an upper level disturbance and associated weak
frontal boundary move across the region. precipitation amounts
have been minimal so far overnight, with a few sites in pacific
county reporting 0.10-0.15" but all other locations north of a
portland to tillamook line only reporting a few hundredths to
this point. forecast precipitation amounts therefore remain on
track with previous thinking, with final totals likely to range
from a tenth or two of an inch from the cowlitz valley down to
portland and only a few hundredths from salem to eugene. light
rain will give way to partial clearing and a few breaks of
sunshine across the area by early this afternoon as the system
pushes east, with a few showers possibly lingering over the
cascades through this evening. expect afternoon highs running
near or slightly above seasonal norms in the mid to upper 60s
inland and in the 50s along the coast this afternoon.

warm and dry weather prevails on wednesday as another upper
level ridge begins to build into the region, with afternoon
highs ranging from the upper 60s to low 70s in the interior
lowlands. temperatures still look to spike on thursday as the
ridge amplifies directly overhead, sending 850 mb temps into the
13-15 c range. this should correspond to highs reaching the 80s
across many interior valley locations, which is supported by
nbm probs now giving the portland metro a greater than 95%
chance to reach 80 degrees and other valley locations a 80-90%
of doing so. the portland area also has around a 75% chance to
reach 85 degrees but notably only about a 3% chance to reach 90
degrees, placing an upper bound on how high temperatures may go
on thursday afternoon. taking a look at nws heatrisk guidance,
all locations remain in the minor category, likely owing to the
short duration (only one day) of well above normal temperatures
and overnight lows still dropping into the 50s. meanwhile,
marine influences still look to keep coastal locations much
more mild with temperatures topping out in the 60s in those
communities on thursday. /cb

.long term...friday through monday...wpc ensemble clusters
continue to indicate a return of upper level troughing friday
into the weekend as the ridge shifts east of the region,
ushering in another period of potentially wetter weather as
temperatures return closer to seasonal norms in the 60s.
if you are looking for rainfall amounts that will significantly
move the needle coming out of this very dry april,
models unfortunately do not provide much optimism as
probabilistic guidance gives most areas only a 20-30% chance to
receive a wetting rain of a quarter inch both friday and
saturday. from a pattern recognition standpoint, will at least
have to keep an eye on the potential for a few thunderstorms
near the crest as upper level flow turns more southerly late
friday into saturday, but models are not particularly bullish
on this scenario at this time. ensembles increasingly favor a
return of upper level ridging late sunday into the beginning of
next week, with temperatures trending back upward and
precipitation chances trending downward as a result. /cb

&&

.aviation...at 0945z tuesday, radar and surface weather
observations showed light stratiform rain associated with a weak
cool front beginning to spread eastward over southwest wa and
northwest or. surface visibilities are generally at or above 6 sm
where rain is falling, except at kast where visibilities have
fallen to 2-3 sm. expect visibilities to drop to a similar range
at konp by 12-14z tuesday. cigs are already deteriorating to ifr
at the coast and should fall into mvfr thresholds for inland taf
sites by 12-15z. in addition, cannot rule out periods of lifr
cigs at the coast tuesday morning (35-45% chance for both kast
and konp).

conditions will trend back to vfr between 21-24z tuesday in the
wake of the aforementioned front as cloud cover scatters out.
conditions will also be dry by that point aside from a few stray
light rain showers. -tk

pdx and approaches...periods of light stratiform rain will
continue through 15-16z tuesday with a few stray light rain
showers around the portland metro thereafter. chances for mvfr
cigs below 3000 ft have increased to 70-90% between 13-18z
tuesday. conditions will otherwise improve back to vfr by 21-24z
tuesday as cloud cover scatters out. light and variable winds
should eventually become northwest by 22z tuesday, sustained
around 5 kt. -tk

&&

.marine...a weak cool front will move over the coastal waters early
to mid tuesday morning. winds will veer to the northwest behind
the front, albeit winds will remain weak at 5-15 kt. periods of
light rain will also accompany the frontal passage.

high pressure returns late tuesday morning in the wake of the
front and then remains in place through friday, resulting in
benign conditions with seas under 10 ft and winds generally under
20 kt. that said, northerly winds may briefly gust as high as
21-23 kt for a few hours late wednesday afternoon and evening over
the southern waters. -tk

&&

.pqr watches/warnings/advisories...
or...none.
wa...none.
pz...small craft advisory until 9 am pdt this morning for pzz210.

&&

$$

www.weather.gov/portland

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