Nisson, Washington Weather Forecast Discussion

937
FXUS66 KSEW 182143
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
243 PM PDT Thu Sep 18 2025
.SYNOPSIS...Dry and mild weather conditions through Friday. The
next system will arrive this weekend, bringing widespread rain
and breezy winds to the region. Conditions will dry out early next
week as high pressure builds into the region.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY/...There`s weak troughing over
western WA today with overall mild conditions. Smoke from the Bear
Gulch wildfire is now drifting south and over Mason, Grays Harbor,
Thurston and western Lewis counties. However, the plume itself is
a more thin/diffuse on satellite and air quality remains good.
Overnight lows will dip into the mid 40s to lower 50s overnight.
On Friday, there`s weak upper level ridging overhead for a slight
uptick in temperatures. Highs will reach the mid to upper 70s in
the interior. The coast will see 60s with ongoing onshore flow.
Winds at 850 mb remain northerly with smoke still drifting south
from Bear Gulch.
Wetter weather is in store for Saturday-Saturday night as a
Pacific frontal system shifts inland. The model trend on timing
has been slower and it still looks like the interior will remain
dry trough the morning. Rain will then spread inland mid to late
afternoon and evening. We`re in post-frontal onshore flow on
Sunday with additional showers and a convergence zone over the
central sound. All told, we`re looking at good wetting rains along
the coast, Olympics and Cascades with 0.50-1.00" of rain through
the weekend - thus keeping fire danger low. In the lowlands, the
ranges are closer to 0.25-0.50" totals. 33
.LONG TERM /MONDAY THROUGH THURSDAY/...A ridge builds to our south
Monday and Tuesday with zonal flow over western WA. A weak system
moves into B.C. which may clip the coast, otherwise we`re looking
mostly dry. The flow does turn offshore again with temperatures
trending above normal and a few low 80s possible (like in the Cascade
foothills, south sound). Moisture spreads north mid to late week
reintroducing a chance of showers. 33
&&
.AVIATION...VFR across the majority of the terminals, with the
exception of BLI. Latest satellite imagery suggests the low clouds
will erode after 22z and conditions will rebound to VFR. Otherwise,
VFR expected to prevail the rest of today. Guidance is hinting at
another round of low stratus at the coast tonight, bringing IFR/LIFR
ceilings. Majority of interior terminals are expected to remain
mostly clear overnight. Although guidance is hinting at potentially
seeing lowered ceilings for BLI. with a 35%-40% of MVFR and 20%25%
of IFR. The combination of mostly clear skies and calm winds may
lead to fog formation at typical fog-prone locations. Latest
guidance hints at OLM having the greatest chance. Improvement into
VFR for the coast and any interior terminals that see low
ceilings/fog is expected after 18z-20z. Northerly winds will keep
smoke away from CLM, but may drift it towards Shelton and Olympia
this afternoon.
KSEA...VFR expected to prevail through the TAF period with mostly
clear skies. Not expecting any fog formation at the terminal. Breezy
conditions this afternoon from the north-northwest at 7 to 10 kt.
Winds will shift tonight to the northeast(around 5z-6z) at 6 to 7 kt
and will ease into the overnight hours to 3 to 5 kt. Northwesterly
winds return late Friday morning at 6 to 7 kt.
29
&&
.MARINE...High pressure over the coastal waters today through
Friday. A cold front will traverse the waters this weekend, bringing
an increase in southwesterly winds. The latest guidance continues to
hint that the greatest chances of seeing Small Craft Advisory winds
are in the central portion of the Strait of Juan de Fuca with
probabilities at 30%-50% from Saturday afternoon through Sunday
evening. In addition, guidance hints at winds briefly meeting small
craft criteria for the interior waters, with the highest
probabilities for the northern interior waters at 50%-70%. Winds
will ease on Monday. Another cold front will move over the waters on
Tuesday.
Seas will continue to subside today into Friday and will build to 6
to 9 ft over the weekend. Seas will hover around 6 to 8 ft into
early next week.
29
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 PM PDT this afternoon for Coastal
     Waters From Cape Flattery To James Island 10 To 60 Nm-
     Coastal Waters From Cape Flattery To James Island Out 10 Nm-
     Coastal Waters From James Island To Point Grenville 10 To
     60 Nm-Coastal Waters From James Island To Point Grenville
     Out 10 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville
     To Cape Shoalwater Out 10 Nm.
&&
$$

NWS SEW Office Area Forecast Discussion