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

fxus66 kpqr 052022

Area Forecast Discussion
National Weather Service Portland, OR or
122 pm pdt sun apr 5 2020

.synopsis...showers will end tonight as high pressure builds aloft.
stratus will likely fill in a long the coast and inland valleys late
tonight and monday morning for a cloudy start to the work week.
clearing in the afternoon will lead to near normal daytime
temperatures monday afternoon, high pressure will support dry weather
through at least friday. temperatures will get close to 70 degrees on
thursday which will likely be the warmest day of the week.


.short through tuesday night...satellite and radar
imagery is almost a spitting image of those from 24 hours ago with a
low pressure offshore the north ca/sw oregon coast generating rain in
northern california and sw oregon. the rain has again been slow to
reach the portland forecast area, but is on the way. a band of
showers is getting close to south lane county and will probably be
over florence, creswell,l and cottage grove, within the hour and
possibly to eugene and newport by the time this discussion becomes

elsewhere, high clouds have been slowly clearing revealing a layer of
stratus across the south willamette valley that is now eroding.
clouds this morning slowed todays heating, but a couple of hours of
sunshine will allow the daytime temperatures to rise a few more
degrees this afternoon. the clearing and heating will enhance the
possibility for thunderstorms this afternoon, which still looks a
decent chance for the central oregon cascades. thunderstorms are
starting to sprout with the front over ne california early this
afternoon which provides further support that thunderstorms are
possible as remnants of this front lifts north over sw oregon later
this afternoon and early this evening.

the best possibility for late afternoon thunderstorms is over the
lane county cascades and foothills with a lesser chance for inland
lane and linn counties. the modeled instability for portland and sw
washington in general is too low to include a mention of a threat
there. however, convective debris in the form of clouds and light
rain is possible in the northern areas later this afternoon and this
evening if the thunderstorms get going south or east of the area,
thanks to 0-6 km agl south to southwest flow.

the low will slowly move south further into california tonight and
monday as an upper level ridge begins to build between the low and an
upper trough north of the columbia basin. this will result in
decreasing showers across nw oregon. showers may linger across the
the lane county cascades monday, but otherwise dry weather with
decreasing clouds is expected through the day on monday.

with lingering surface moisture, increasing subsidence, and light
winds, expect stratus along the coast and inland late monday night
into tuesday morning. these clouds will clear in the afternoon but
slow the daytime warming such that there will be little change in
afternoon temperatures between monday and tuesday. drier low levels,
and increased subsidence under a slightly stronger upper ridge will
result in less stratus coverage tuesday night.~tj

.long term...wednesday through saturday night...models and ensembles
forecast a rex blocking pattern trying to set up wednesday with an
upper level high over the pacific nw and an upper low over southern
california. this will result in at least a few days of dry weather
with daytime temperatures gradually warming. models suggest that an
upper level trough moving over the top of the ridge will dig south
into the columbia basin on friday, and shorten any warming trend.
therefore, it still looks like thursday will be the warmest day of
the week. light onshore flow will maintain near normal temperatures
along the coast that will peak in the mid 50s.

although temperatures will be cooler thursday and friday, the upper
ridge will maintain its position over the pacific nw and continue dry
weather. weather models are notorious for breaking down blocking
pressure patterns too quickly, and begin to diverge in their
solutions friday night when some pop mentions are reintroduced to the
forecast. due to the long-lasting nature of blocking patterns suspect
that dry weather may extend into the weekend, but have leaned towards
the ensemble trend of slight chance pops for now. ~tj


.aviation...low pressure off the southern oregon coast is
shifting south. satellite is showing high clouds moving out of
the area and ceilings are starting to breakup with a dominant
broken ceiling across the area around 5000 ft. northerly winds will
continue through the night and into monday morning. unstable
conditions south of a kuao to konp line will bring a chance of
thunderstorms this afternoon, early evening. chance of
thunderstorms increase with increasing proximity to keug and

as the offshore low moves south a mesolow will split and move
inland after 03z monday. this will primarily affect the southern
half of the cwa bringing an increase in clouds aloft and mvfr
ceilings to keug by 10z and ksle by 13z. this weak system looks
to break up by 16z mon. high pressure will build behind the
primary low increasing the likelihood of patchy fog between 10z
and 17z for low-lying areas.

pdx and approaches...vfr conditions with northwesterly winds to
persist throughout the day. chance of rain showers late this
evening. slight chance of thunderstorms south of kuao to konp
line. -bphillips


.marine...low pressure near coos bar will slowly move south
sunday night. a weak mesolow will split from this low and move
inland over night which will increase winds in pzz250 and pzz255.
sca winds will ramp up in the late afternoon and continue
overnight. high pressure builds offshore and overnight winds
weaken. models are showing a persistent thermal trough pattern
over northern california through the week. this pattern will
increase winds in the central oregon waters in the late
afternoon, early evening. wind gusts near 25 kt should be

persistent northerly winds will increase wind waves in the
afternoon but the overall trend will stay between 4 to 6 ft
through wednesday. -bphillips


.pqr watches/warnings/advisories...
pz...small craft advisory until 8 am pdt monday for coastal waters
     from cape shoalwater wa to cascade head or out 60 nm.

     small craft advisory until 11 am pdt monday for coastal waters
     from cascade head or to florence or out 60 nm.

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this discussion is for northwest oregon and southwest washington
from the cascade crest to 60 nm offshore. this area is commonly
referred to as the forecast area.

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