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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 pst sun feb 19 2017

.synopsis...an active weather pattern will bring periods of rain and
mountain snow to southwest washington and northwest oregon through
much of this week. an occluded front was moving through southwest
washington and northwest oregon early this morning, followed by
showers and isolated thunderstorms associated with the parent low
that is off the coast. the next low will move in from the southwest
for more rain later tonight and monday. another low will follow
shortly behind it later monday night and tuesday for more rain and
mountain snow. snow levels will be below the cascade passes through
monday morning with the higher elevations of the coast range possibly
having a couple of inches of snow early sunday morning, then briefly
rise monday before falling again through the rest of the week. gusty
winds are expected for the coast today with possibly stronger winds
monday afternoon. snow levels will lower into at least the cascade
foothills and the coastal mountains during the middle of next week
and beyond, but with limited moisture.
&&

.short term...today through tuesday...a longwave upper trough is
expected to remain off the coast between around 130w to 140w for the
next few days as a series of weather systems moves through the
pacific northwest. the first was an occluded front that was moving
through northwest oregon and southwest washington overnight and early
this morning. a trailing showery air mass will be over the forecast
area today with a few thunderstorms as well. we have seen lightning
already over the coastal waters and near florence early this morning.
as a result, some of the showers could have small hail as well today.
snow levels will be below the cascade passes today, but the only area
that looks to get advisory type snow amounts will probably be just
the south washington cascades. may see a little dusting of snow in
the higher elevations of the coast range and in the cascade foothills
as well today.

this will be followed by another low approaching the forecast area
from the southwest tonight, and moving through on monday. the models
are still having a tough time coming into agreement on timing,
intensity, and track of this low. nevertheless, there is a good
chance of fairly strong winds along a good portion of the oregon
coast monday, with a decent shot of rain and mountain snow. the snow
level may rise a bit ahead of the low early monday but then drop back
down to around the passes behind it later monday. there is a chance
of reaching snow advisory amounts on monday in the south washington
and the north oregon cascades, but probably not in the lane county
cascades.

the models show another low tracking through the area monday night
and tuesday for more rain and mountain snow. these systems should
finally begin adding a decent amount of snow again to our snow pack.
tolleson

.long term...no changes. previous discussion follows...
tuesday night through saturday...upper-level trough sets up off the
coast early next week, keeping the jet stream and the stream of
tropical moisture south over california. this will lead to a drying
trend across southwest washington and northwest oregon. though the
bulk of the moisture will be to our south, weak shortwaves under the
trough could generate a few showers through the end of this week.
moisture will be limited, however, so not expecting any significant
qpf. as the trough moves into the pacific northwest, snow levels will
be falling, possibly below 1000 feet by thursday morning. with snow
levels this low, can`t rule out a few flurries making it down to
higher elevations near the valley floor, but again, moisture will be
very limited so we will likely not see any snow make it down even
near the valley floor. we will need to monitor next weekend or early
the next week as we could see a system move in with this cooler
airmass in place, leading to a period of mixed precipitation before
transitioning to all rain. -mccoy
&&

.aviation...a mix of vfr and mvfr across the forecast area early
this morning as an occluded front moves across the area. showers
have arrived at the coast and expect steadier rain inland to
change over to showers by 13z. with the more unstable air mass
vfr conditions should dominate but still may see mvfr cigs and/or
vis with heavier showers. isolated thunderstorms are occurring
near the coastline early this morning. thunderstorms are also
possible inland later this morning through the afternoon.

winds pick up out of the south starting this morning and could
sees gusts as high as 30 kt along the coast and gusts in the 15
to 20 kt range inland.

kpdx and approaches...light rain with occasional cigs around
2000 to 3000 ft through about 15z sun the trending toward vfr.
there may be brief mvfr conditions with heavier showers today.
also there is a small threat for thunderstorms in the area
between 15z sun and 00z mon.  /mh
&&

.marine...initial occluded front moved northeast into the waters
brought gale force wind to the central oregon coastal waters
(pzz275/255.) buoy 46050 off newport had gale gusts for several hours
and has begun to ease a bit as of 1 am. expect gales to lower to
small craft southwesterly wind by 4 am and further ease in the late
afternoon and evening. the parent 990 mb low associated with the
front is about 230 nm west of newport at 1 am and will cross about 70
nm west of astoria this morning as it heads toward the north
washington coast. this will likely bring gale force gusts to to the
north oregon coastal waters (pzz250/255) through this morning. winds
will turn southwesterly and decrease a bit behind the low this
morning, but still expect solid small craft advisory winds to
continue into this evening.

there have been a few thunderstorms over the coastal waters overnight
and may see more through this morning.

the active weather pattern continues as another potentially strong
low will affect the waters mon. there is still uncertainty on the
strength and track of this system. there is definitely potential for
gales over most of the waters. there is enough confidence to issue a
gale watch for the central oregon waters (pzz275/255) for monday.

seas are currently around 7 to 8 ft and will be rising today to the
low teens this morning then into the mid teens by this afternoon or
evening. the seas fcst for mon is tough, given the uncertainty in the
surface low track. the stronger solutions would suggest seas
approaching 20 ft are a possibility. will keep the fcst in the mid
teens for now. pyle /mh
&&

.pqr watches/warnings/advisories...
or...none.
wa...winter weather advisory until 7 pm pst this evening for south
     washington cascades.

pz...gale warning until noon pst today for coastal waters from cape
     shoalwater wa to cascade head or out 60 nm.

     gale watch from monday morning through monday afternoon for
     coastal waters from cascade head or to florence or out 60
     nm.

     gale warning until 4 am pst early this morning for coastal
     waters from cascade head or to florence or out 60 nm.

     small craft advisory for rough columbia river bar from 9 am
     this morning to 1 pm pst this afternoon.

&&

$$

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

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