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

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Area Forecast Discussion...updated
National Weather Service Portland, OR or
842 am pdt sat jul 31 2021

.synopsis...a persistent weather pattern will continue above average
temperatures and a risk for light showers and possibly a
thunderstorm, primarily over the cascades, into early next week.
temperatures should then drop closer to or even below average with a
better chance for precipitation towards the latter half of next week.

&&

.short term...today through monday...our weather continues to
be driven by the southerly flow created by a gulf of alaska low and
an upper ridge stretching along the rocky mountains into british
columbia. cloud top cooling on water vapor and ir satellite data, as
well as an uptick in showers evident on radar, lines up well with a
speed max in the upper levels gliding along the or coast. even a few
elevated thunderstorms have been able to grow just offshore in this
nighttime environment. convective allowing models have been showing
this increased activity overnight, and will expect this activity to
die down in the next few hours as mid-level lapse rates weaken and a
mid-level theta-e ridge retreats back south again.

looking upstream, monsoonal moisture feed into the area looks to
continue, keeping good cloud cover over the forecast area for the
day. this will bring temperatures down today with readings only in
the low 80s to low 90s across the area except the coast where
readings should be in the low 60s. instability will increase again
with the cascade mountains likely to see isolated to scattered
showers again and a slight chance of thunder.

moisture then dries out again for sunday for mostly clear to partly
cloudy skies, however 500mb heights will decrease slightly as the
troughing to our west nudges in a bit, resulting in temperatures
nearly the same or a degree or two warmer. a drier airmass will limit
convection as well. monday will remain very similar weather wise to
sunday as the weather pattern remains almost unchanged. the one
difference is models continuing to show a weak shortwave trough
lifting northward off the northern california coast sunday night into
monday that could allow for a bit more convection to develop across
our southern zones. /kriederman

.long term...monday night through thursday...cluster analysis
continues to show oregon and washington remaining under southerly
500mb flow between the stationary trough in the gulf of alaska and
the longwave ridge extending across much of the eastern 2/3 of the
country. a piece of energy from the gulf of alaska low is depicted by
all three long range models (gfs, cmc, ecmwf) to peel off the parent
low and drop offshore of california during the first half of the
week, then pass into our area wednesday or thursday, but its exact
timing and placement are somewhat uncertain. this looks promising to
bring a better chance for precipitation to much of our cwa during the
wednesday through thursday timeframe. for now, we have gone with
nbm`s forecast, which has a chance of showers north and a slight
chance south during this time period. the nbm also suggests it will
be cooler - near to slightly above normal - during this period with
only around a 25% chance for exceeding 90f at pdx by thursday.
-bumgardner/kriederman

&&

.aviation...not much change, as will maintain vfr with plenty of mid
and high clouds with south to southeasterly flow aloft. air mass
remains unstable, with scattered showers and a few thunderstorms,
mainly along the coast north of astoria until 18z, as well as over
the cascades into eastern or/wa. will see showers and thunderstorms
redeveloping over the cascades this afternoon, with movement such
that most will stay over the cascades and foothills. at this point,
only isolated showers expected on to the west of the foothills.

pockets of ifr to mvfr stratus along the coast will surge back
onshore this afternoon, spreading over most of the coastal lowlands
this evening. should see see this stratus also pushing up the umpqua
and siuslaw drainages overnight.

for detailed regional pac nw aviation weather information, go
online to: https://weather.gov/zse

kpdx and approaches...vfr, but will have considerable mid and high
clouds over the ops area. can expect a passing shower after 21z, but
higher potential of showers and a few thunderstorms over the
cascades today into early this evening, possibly affecting eastern
approaches/departures.

&&

.marine...the typical summertime n-nw wind pattern continues
across the coastal waters through the middle of the upcoming
week. expect gusty north to northwest winds in the afternoon and
evening hours. there is the potential during each afternoon and
evening for some isolated gusts up to 25 kt in all zones.
better chance for widespread gusts to 25 kt starts sunday
afternoon for mainly for the outer zones. current models show
this potential lasting through tuesday.

later in the week, models show a weakening trough moving to the
waters wednesday into thursday to shift winds to the west then
southwest. this system is attempting to push into the strong high
pressure inland, so it could weaken further and/or be delayed
with later model runs.

seas remaining in the 4 to 6 ft range, mainly driven by wind
waves and a small westerly swell.  /mh

&&

.pqr watches/warnings/advisories...
or...none.
wa...none.
pz...none.

&&

$$

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Information courtesy of the National Weather Service - NWS Portland...
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