344
FXUS66 KSEW 160923
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
123 AM PST Mon Feb 16 2026
.SYNOPSIS...
A return to an active weather pattern begins today with a
trough developing offshore. A few fronts associated with this
trough will keep precipitation chances in the forecast through
the week, including snow in the mountains. Temperatures this
week will also be a couple degrees cooler, with highs in the 40s
and lows around freezing for much of the week.
&&
.SHORT TERM /TODAY THROUGH TUESDAY NIGHT/...
It is mostly dry this morning across western WA this morning,
but that is quickly changing. A trough is expected to develop
offshore in the Pacific today, and dig its way southward along
the coast, with much of the jet energy focused in California.
This trough is expected to be the primary trigger for some of
the weather expected in western WA through much of the week.
Already on radar this morning, the first showers are approaching
the coastline from a cold front offshore that is expected to
stall once it gets to the coast. These showers have been light
in nature as of midnight, but will increase in intensity/coverage
going through the day. The expected mode of precipitation today
is bands/areas of showers. There is enough cool air aloft (from
850 mb up to 500 mb) for some instability in the air today
(particularly from the coast into the ocean today). This has
resulted in a 20% chance of thunder for today`s shower activity
along the coastline, and offshore. In addition to the chance of
thunder, there is a chance of some snow mixing in (especially as
snow levels drop below 1,000 ft late tonight, and below 500 ft
Tuesday morning). As far as impacts go for today/Tuesday, the
main area of concern is the US-101 corridor from Forks to the
Lake Crescent area, where HREF/REFS keep probabilities for 1" of
snow at 70-80% (but drops to 50% for 2" of snow). This area of
US-101 will continue to be monitored for a possible winter
weather advisory as the morning evolves (there remains some
uncertainty as to if warmer air from the onshore flow may
disrupt some of the cool air down at the surface causing flakes
to melt).
For the remainder of the region, shower coverage is not expected
to be as widespread as the coast today, but a few showers will
work their way inland into the interior today into Tuesday.
While a few snowflakes may fall in some of the more urban areas,
the threat of accumulating snow (an inch or greater) in the
interior remains near 0. The snow will be primarily focused in
the Olympics/Cascades, with some of the snow in the Olympics
potentially reaching down to the Lake Crescent and Hood Canal
areas tonight/Tuesday morning. The snow amounts in the mountains
Monday-Tuesday are on the lighter side, with just around 1-2
inches in the passes, and 3-6 inches at the peaks of the
mountains.
High temperatures Monday/Tuesday will range in the low to mid
40s for the lowlands, and 20s/30s in the mountains. Winds will
be out of the south/southwest, with a few gusts to 20 mph
possible in the interior Monday afternoon, otherwise decreasing
in magnitude into Tuesday to around 5 mph.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The same trough will remain in place over the region through
Friday, before moving further inland. This will keep
temperatures cool through the week, with precipitation chances
continuing. With the precipitation mode expected to continue to
remain showery, some uncertainty remains in exact amounts of the
precipitation going into the second half of the week. The snow
impacts will shift more towards the mountains (though a few
flakes will continue to remain possible in the lowlands next few
overnights). The Cascades and Olympics will see snow through the
week, with snow rates expected to remain light enough to keep
traffic impacts to a minimum. From early Wednesday through
Friday the heaviest of the snow looks to be in the central/south
Cascades (with potential for 6+ inches of snow in a few of the
passes/peaks Wednesday through Friday).
There are split ensemble solutions as to what replaces the
previously mentioned trough moving inland. Most members show
another trough developing next weekend, while a couple members
show a drier/warmer pattern to the east (but just clipping
western WA). If a trough does develop, there will be potential
for more precipitation, as temperatures increase slightly next
weekend. The precipitation will be monitored for possible
impacts to travel (as there are signals that some of this
precipitation may be heavier in nature).
HPR
&&
.AVIATION...
A trough will dig along the coast today, with a surface cold
front associated with the trough expected to slow as it
approaches the coast. This will increase southwest flow aloft.
Ceilings this morning are mostly VFR (couple pockets of MVFR
are present around KPAE and KPWT, with mist down at KOLM).
Scattered showers are expected across the terminals in the TAF
period. Most of the showers will be concentrated from the
Olympics westward, but a few will track in the interior.
Additionally, the air along the coast/Pacific ocean is unstable
enough for a 20% chance of thunder today. Some of the heavier
showers may drop visibilities down to IFR. Additionally, the
cool air overnight may lead to a few snowflakes mixing in
overnight/early Tuesday morning. Probability for widespread MVFR
ceilings increases tonight/Tuesday morning, but some terminals
may stay VFR. Surface winds today are out of the SW 5-10 kt
(couple gusts to 20 kt possible in the interior this afternoon).
Will drop to 4-6 kt tonight/Tuesday.
KSEA...VFR high clouds in place over the terminal, with a 60%
chance of showers/vicinity showers from 18Z through 00Z, then a
20% chance of vicinity showers through the remainder of the TAF
period. A few snowflakes cannot be ruled out mixing down Tuesday
morning (if a shower passes over the terminal). Probabilities
for MVFR becomes likely after 00Z this evening. Winds: SW 5-10
kt with a couple gusts to 20 kt from 18Z-03Z, decreasing to 4-6
kt tonight/Tuesday.
HPR
&&
.MARINE...
A trough is expected to deepen offshore in the coastal waters
today, and remain over the region through the end of the week
before moving inland. A couple of surface fronts will pass
through with this trough pattern (the first one expected to slow
coming up to the shore today/Tuesday). Precipitation will be
showery in nature, with there also being a 20% chance of thunder
in the forecast (for Monday only). Winds with this front are
only expected to exceed 20 kt in the far outer coastal waters
this morning through the afternoon. The winds will be breezy
elsewhere out of the south (up to 15-20 kt gusts in the
interior), but below small craft headline criteria. The hazard
concern transitions to high seas, with an increase to 10-13 ft
expected late today into Wednesday, decreasing to 7-8 ft
Thursday, and 4-6 ft Friday as the low moves inland. Some
uncertainty remains if a system will develop next weekend, but
there will be a potential for gusty small craft winds and seas
building above 10 ft next weekend (depending on how the system
tracks).
HPR
&&
.HYDROLOGY...
No river flooding is expected over the next 7 days.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 4 PM Monday to 4 AM PST Tuesday for
Coastal Waters From Cape Flattery To James Island Out 10
Nm-Coastal Waters From James Island To Point Grenville
Out 10 Nm-Coastal Waters From Point Grenville To Cape
Shoalwater Out 10 Nm.
Small Craft Advisory from 4 AM Monday to 4 AM PST Tuesday for
Coastal Waters From Cape Flattery To James Island 10 To
60 Nm-Coastal Waters From James Island To Point Grenville
10 To 60 Nm-Coastal Waters From Point Grenville To Cape
Shoalwater 10 To 60 Nm.
&&
$$
NWS SEW Office Area Forecast Discussion