Elbe, Washington Weather Forecast Discussion

637
FXUS66 KSEW 291055
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
355 AM PDT Mon Sep 29 2025
.SYNOPSIS...A frontal system will push through Western Washington
today. A stronger frontal system is expected Tuesday through
Wednesday. These systems will bring widespread rain, breezy to gusty
winds, and a slight chance of thunder. Unsettled conditions are
favored to continue late into the week as additional systems move
into the region.
&&
.SHORT TERM /TODAY THROUGH WEDNESDAY/...A frontal system continues
to push across Western Washington early this morning. Latest
satellite imagery as of 350 AM shows light to moderate rain
making its way along the coast and a few light showers moving
across the interior locations. This weather system will bring
breezy to gusty winds to the coast, locations along the east
Strait, and northern interior Monday morning. There is high
confidence (80-90% chance) of seeing wind gusts exceed 25 mph for
the east Strait and Whidbey Island, while there is medium to high
confidence (50-80% chance) for the northern interior. There is
medium confidence (40-65% chance) of seeing wind gusts exceed 35
mph for locations along the east Strait and Whidbey Island. There
is a slight chance (10-25%) of thunder this afternoon, with the
highest chances along the Olympic Peninsula and Cascades. Rainfall
totals with this system will range between 0.10-0.50 inches in
the interior, 1.00-2.00 inches for the Olympics and Cascades, and
0.50-1.00 inches along the coast.
A stronger frontal system associated with an upper level low
offshore will move through Western Washington Tuesday through
Wednesday. This system will bring more rain than the last system.
WPC has included the Olympic Peninsula under a marginal risk for
their Excessive Rainfall Outlook, indicating at least a 5% risk
for significant rainfall. Latest guidance suggests, the Olympic
Peninsula may see between 2.00-4.00 inches of rain, with higher
amounts in the mountain peaks. As for other locations, 0.25-1.00
inches in the interior and 1.00-3.00 inches in the Cascades. In
addition, this system will bring breezy to gusty winds and the
chance for thunder. There is high confidence of seeing wind gusts
exceed 25 mph along the coast, east Strait, Whidbey Island, and
northern interior. Stronger winds will be along the coast, east
Strait, and Whidbey Island, where there is medium confidence
(40-60% chance) of seeing gusts exceed 35 mph. Latest model runs
have trended higher on the chance of thunder for Tuesday and
Wednesday. On Tuesday thunder chances (20-30%) will be mostly
confined to the coast, with a smaller chance (10-15%) in the
interior. On Wednesday evening , thunder chances are slightly
higher; guidance suggests a 20-40% chance for the Olympic
Peninsula and a 15-20% chance for other locations.
Wave heights along the coast will approach 15 feet or higher on
Wednesday. This may generate hazardous surf conditions with waves
running higher on beaches that can sweep people off jetties and
breakwaters. Beach erosion is also possible.
.LONG TERM /THURSDAY THROUGH SUNDAY/...Latest deterministic
models and ensemble data are coming to a general agreement that the
center of upper level low offshore will move through Western
Washington on Thursday. This will keep unsettled conditions late
into the week. However, uncertainty still remains over the weekend
on the upper level pattern. Latest ensemble guidance shows zonal
flow is likely behind the upper level low on Friday with with
another upper level trough following on Saturday and Sunday.
29
&&
.AVIATION...Southwesterly flow aloft will persist through the TAF
period with upper level troughing over the region. A slow moving
frontal system will continue to push inland this morning, bringing
rain and gusty southerly winds to the area terminals. Radar shows
the heaviest rain continuing to push inland along the coast early
this morning, with the bands of heavier precipitation likely to
push inland into the interior terminals between 16-19Z. Expect
ceilings to lower towards MVFR and for terminals to see reduced
visibilities as the front pushes through. Gusty southerly winds
to 25 kt will also be possible for area terminals in the vicinity
of the front. A slight chance of thunderstorms is possible area-
wide this afternoon and evening, but confidence in occurrence is
too low to include in TAFs at this time. Gradually improving
conditions are then expected by the afternoon with residual
showers tapering this evening.
KSEA...VFR conditions with light SE winds early this morning.
Expect winds to increase through the morning hours, with gusts to
25 kt possible around the frontal passage. Ceilings and visibilities
will lower towards MVFR conditions as the front moves inland and
brings rain to the terminal. Conditions look to gradually improve
this afternoon, with showers tapering tonight.
14
&&
.MARINE...A slow-moving frontal system will continue to cross the
area waters this morning, bringing gusty winds to the coastal
waters, the Eastern Strait of Juan de Fuca, Admiralty Inlet, and
the Northern Inland Waters. Frequent gusts to gale force are likely
across the eastern Strait through the late morning hours. Winds
will then ease again by this afternoon for a brief lull in between
systems. Latest observations show steep seas across the coastal
waters currently persisting between 10-12 feet with an average
period around 8 seconds. Seas will become less steep through the
morning and will gradually subside back to 8 to 9 ft.
A stronger frontal system will then move across the area waters
Tuesday into Wednesday, likely bringing gales to the coastal
waters, the Eastern Strait of Juan de Fuca, and portions of the
Northern Inland Waters. Confidence remains high in the occurrence
of gales, with latest probabilistic guidance showing a 75-90
percent probability of gale gusts across the coastal waters and a
45-55 percent probability across the East Strait/Northern Interior
Waters. Thus, a Gale Watch remains in effect for these areas.
Elsewhere, the majority of the remaining marine zones will likely
see gusty winds of at least SCA criteria during this period. Waves
over the coastal waters will build towards 15-18 ft and will
primarily be southerly associated with the frontal passage, then
will transition to more westerly by Wednesday.
Winds will decrease through the day Thursday and into Friday as
the low pressure system associated with the front weakens and
starts to move inland. Seas will gradually fall back below 10 ft
on Thursday. High pressure will then build back into the northeastern
Pacific late in the week, shifting winds back to the northwest
over the coastal waters.
14
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Gale Warning until 11 AM PDT this morning for East Entrance U.S.
     Waters Strait Of Juan De Fuca.
Gale Watch from late tonight through Wednesday morning 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-East Entrance U.S.
     Waters Strait Of Juan De Fuca.
Small Craft Advisory until 11 AM PDT this morning for Admiralty
     Inlet-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-Northern
     Inland Waters Including The San Juan Islands.
&&
$$

NWS SEW Office Area Forecast Discussion