Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
876
FXUS66 KSEW 041603
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
901 AM PDT Sun Oct 4 2026
.SYNOPSIS...
High pressure overhead and a thermal trough shifting inland
today will provide one more day of mild temperatures. A system to
the north will flatten the ridge Monday, with near-zonal flow aloft
and onshore flow at the surface maintaining seasonable conditions,
morning clouds and afternoon sun breaks throughout the week. Chances
for rain increase by next Friday, though confidence remains low.
&&
.SHORT TERM /TODAY THROUGH TUESDAY/...
Current satellite imagery not too dissimilar from 24 hours ago with
stratus and fog largely dominating the interior lowlands while
higher elevations are party to clear skies. There are exceptions to
this, such as while the river valleys in the SW interior are socked
in, not so much for the remainder of the area. Also worth noting is
that while the coast is also partaking of the foggy conditions, the
northern and southern portions /from UIL north and from HQM south/
are seeing generally clear conditions. As such, inherited Dense Fog
Advisories will remain in place as locations within those headlines
still seeing visibilities of less than 1/2 mile. The gap between the
two advisories along the I-5 corridor, including the Seattle and
Tacoma metro areas, will remain outside of headline consideration at
this time. While some spots in those areas are meeting criteria, it
is not widespread enough nor consistent enough to warrant inclusion
as visibilities in that area fluctuate. For example, at times here
at the NWS office one could not see the other side of Lake
Washington, yet 15 minutes later it re-emerged from the fog. Will
continue to monitor in case a short-fused headline is needed.
However, with the moisture layer proving to be a little bit thinner
than yesterday at this time, there is some optimism for fog/stratus
to burn off by late this morning. That said, the past few days have
had trouble shrugging off low clouds until the early afternoon
hours...so cautiously taking an around noon-ish approach to when one
can expect to see clouds begin to break up. This might have a degree
or two cooler impact to inherited forecast high temperatures for
today, but not enough change to warrant a morning forecast update.
Remainder of forecast is on track. Please refer to Previous
Discussion section for details.
18
From Previous Discussion...Despite high pressure overhead forcing
light offshore flow, lower levels have not quite dried out enough to
prevent another round of low stratus expanding across the lowlands
this morning. Although slightly drier, low clouds may potentially
linger into the early afternoon once again today. While temperatures
today will once again depend on the timing of the eroding stratus, a
thermal trough shifting inland will aid in warmer temperatures.
Highs across the lowlands are favored to reach the low to mid 70s,
with some areas along the Cascade foothills and valleys reaching the
upper 70s to even lower 80s.
This brief warm-up will be short-lived, however, as the upper
level ridge flattens tonight as a weather system moves inland
over British Columbia. This will bring a return to onshore flow
as near-zonal flow develops aloft, bringing more seasonable
temperatures alongside morning low clouds and afternoon sun
breaks. There will be little change day to day between Monday
and Tuesday, with dry conditions, highs generally in the mid
60s to lower 70s, and lows in the upper 40s to lower 50s.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Much of next week will bring more of the same as zonal flow
aloft and onshore flow at the surface maintain near- normal
temperatures and morning clouds. There will be little change day
to day through Thursday, with highs once again in the mid 60s
to lower 70s and lows in the upper 40s to lower 50s.
Forecast models have come into slightly better agreement over
cooler and wetter conditions on Friday as a trough passes over
the Pacific Northwest. However, models continue to hint that the
incoming frontal system and associated precipitation may break
apart as the system moves into western Washington, which would
by no means bring a wash out. Chances for rain increase Friday
afternoon into Saturday, though the intensity and coverage of
the potential incoming rainfall remain uncertain at this time.
15
&&
.AVIATION...
An upper-ridge and light offshore flow remains across the region
today. West to west-southwest flow aloft with easterly flow in the
lower levels. Patchy fog and low clouds are currently developing
across the area so far this morning. This activity will become
widespread cross the interior and portions of the coast with
IFR/LIFR cigs and vis. VFR conditions are slated to return by 19-
21z. An additional round of low clouds/fog is in store overnight
Sunday into Monday morning as low-level flow turns onshore.
KSEA...VFR as of 0930z but fog/low clouds will spread across the
terminal by 12-14z with IFR/LIFR conditions and remain in place
throughout the morning. VFR skies are to return by 19-21z and last
for the remainder of the day. An additional round of low clouds/fog
is in store overnight Sunday night into Monday morning as low-level
flow turns onshore. Northerly winds 4-8 kt turning more southerly
Monday morning.
41
&&
.MARINE...
One final round of offshore flow today as a thermal
trough forms along the coast. Winds will turn onshore again Sunday
night into Monday as low pressure shifts inland and surface high
pressure builds offshore. Onshore winds will be strongest through
the Strait of Juan de Fuca as a SCA remains in effect for the
central/eastern zones. The NBM has a 50-80% chance of SCA gusts
being met while the REFS is a bit more bullish with 70-90% chance,
increasing forecaster confidence. Westerly pushes are favored
throughout the upcoming week of varying strength. A more organized
system appears favorable towards the week`s end.
41
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Dense Fog Advisory until 10 AM PDT this morning for Downtown
Everett / Marysville Area-Foothills and Valleys of the
North Cascades-Island County-Lowlands of Lewis and
Southern Thurston Counties-Lowlands of Western Skagit and
Northwestern Snohomish Counties-Lowlands of Western
Whatcom County-Shoreline / Lynnwood / South Everett Area.
PZ...Small Craft Advisory from 5 PM this afternoon to 5 AM PDT
Monday for Central U.S. Waters Strait Of Juan De Fuca-
East Entrance U.S. Waters Strait Of Juan De Fuca.
&&
$$
NWS SEW Office Area Forecast Discussion