Renton, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

245
FXUS66 KSEW 221632
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
832 AM PST Sat Feb 22 2025

.SYNOPSIS...An atmospheric river will set up over Western
Washington, maintaining a wet weekend with heavy rain, gusty
winds, and high snow levels across the region. After a brief
break early Monday, a front will bring more rain gusty winds
through Tuesday. High pressure rebuilds over the region around the
middle of the week with mild and mostly dry conditions, though
some shower chances linger near the coast.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...The current forecast remains
on track with no planned updates this morning. 33

Previous discussion...The deep plume of moisture in an
atmospheric river then sets up over the region into Saturday. This
will bring heavy rain, high snow levels, and gusty winds at
times. Temperatures will be rather mild in the strong southerly
flow. A series of embedded impulses will serve as the focus for
the heaviest rainfall. Not much change in the QPF from previous
thinking with general ranges of 4 to 7 inches over the Olympics
and 4 to 5 inches over the Cascades from Saturday through Sunday
night. With the addition of high snow levels and existing snow,
additional water will further add to the runoff into rivers. The
HYDROLOGY section has more details about potential for flooding
through the weekend and into early next week.

In addition, gusty southerly winds will develop at times over the
weekend. An initial round of gusty winds is expected on Saturday,
peaking during the afternoon and evening. NBM probabilities
highlight the coast and areas from Whatcom County and the San Juan
islands south through around northern Whidbey Island and Admiralty
Inlet for the greatest chance of gusts exceeding 45 mph
(generally 50-80%). This may lead to localized power outages and
tree damage and wind advisories have been issued. Breezy winds
will still be expected elsewhere across the region, but with a
lower likelihood of impacts. Another round of breezy winds are
then expected on Sunday, especially for the same favored locations
as Saturday.

After a brief break Monday morning, the next weather system
quickly approaches later in the day. A deepening low, expected to
be around 980 mb, will approach the area before likely turning
northeast toward Vancouver Island. Still a fair amount of spread
in the ensemble guidance with the precise track of this low.
However, confidence remains high that the associated front will
slow and stall and maintain widespread rain during the afternoon
and evening another weather system approaches the area Monday
afternoon. Parent low with this feature, a 980-985 mb low, will
reach 130W due west of the area then make a northeasterly turn.
This will in turn increase the negative tilt of the front slowing
its northerly progress down with the front stalling over Western
Washington in the afternoon. With the low that far west best
chances for gusty/possible advisory speed winds, along the coast
and the Northwest Interior late in the day. Highs again in the
lower to mid 50s with rain all afternoon.

.LONG TERM /TUESDAY THROUGH FRIDAY/...Behind the front on
Tuesday, expect abundant post-frontal showers (and perhaps evening
a flash or two of lightning) and lowering snow levels that could
bring some light accumulating snow back to the Cascade passes.

Ensemble guidance then favors high pressure building over the
region Wednesday and Thursday. This would bring increasingly dry
conditions along with very mild temperatures with afternoon highs
reaching the around 60. However there`s at least some chance of
continued showers into Thursday, especially near the coast but
also inland. Temperatures remain mild but showers may return late
in the week. Cullen

&&

.AVIATION...A mixed bag of ceilings and visibility this morning
with scattered showers across western Washington. IFR conditions
continue along the coast, with mostly MVFR to VFR conditions
through the interior. Expect ceilings to bounce around a bit this
morning before becoming largely MVFR to IFR this afternoon,
perhaps as low as LIFR along the coast, as the next round of
significant rainfall arrives this evening. Conditions will persist
overnight into Sunday morning.

South to southeast winds will increase this morning to around 10-15
kt, with gusts up to 25-30 kt possible. Strongest gusts will be
along the coast and through the northern interior (BLI). As winds
increase, some low level wind shear may be of concern. Wind speeds
will begin to decrease late tonight between after 2Z-4Z Sunday.
Surface flow will remain southerly with winds of 3-6 kt.

KSEA...Ceilings have been bouncing between VFR and MVFR as rain
showers move in and out of the terminal. A second round of
precipitation is expected to begin moving in this afternoon and
expected to persist through the remainder of the TAF period. Expect
MVFR to potentially IFR ceilings and lowered visibilities with the
rain.

Winds will generally be south/southwesterly. Winds are expected to
increase after 22Z, with wind speeds of 12-16 kt and gusts of 20-25
kt possible. Wind speeds will begin to gradually decrease after 3Z-
6Z Sunday below 10 kt.

29/62

&&

.MARINE...A series of frontal systems will keep conditions active
across the area waters through the weekend. A Gale Warning is
currently in effect across the coastal waters, and a Small Craft
Advisory is currently in effect for the Western and Eastern Strait
the northern inland waters, and Grays Harbor. Winds should begin to
subside Saturday night into early Sunday morning. A stronger system
is expected to move across the coastal waters on Monday. There is
still uncertainty regarding its strength and trajectory; however
winds in the coastal waters may approach high-end gale warning
criteria. Winds will begin to gradually subside on Tuesday night
below 21 kt. High pressure will build over the waters on Wednesday
bringing calmer conditions.

Combined seas are expected to increase to 14-17 ft today and then
gradually subside to 10-12 ft by Sunday morning. Waves will build
above 20 ft on Monday night through early Tuesday morning. Waves
will gradually begin to decrease throughout the day on Tuesday
afternoon and remain below 10 ft by the middle of the week.

29

&&

.HYDROLOGY...The potential for river flooding, urban flooding,
and landslides remains elevated this weekend. Snow levels will
increase to above 7000 feet Saturday night into Sunday with heavy
rain falling over the Cascades and Olympics. This combination will
lead to sharp rises on many area rivers and the potential for a
few to reach flood stage. A flood warning is already in effect for
the Skokomish River at Potlach, with the river expected to reach
moderate flooding this weekend. The flood watch remains in effect
for much of the remainder of Western Washington, with the primary
exception being Jefferson, Clallam, and Whatcom counties. The
flood potential outlook (ESF) covers these counties where river
flooding is less likely but still a non-zero chance. Finally,
urban flooding is possible late Saturday through early Sunday
across much of the region with the heaviest rainfall over the
area.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory until 7 PM PST this evening for Admiralty Inlet
     Area-Central Coast-North Coast-San Juan County-Western
     Skagit County-Western Whatcom County.

     Flood Watch from Sunday morning through late Tuesday night for
     Bellevue and Vicinity-Central Coast-East Puget Sound
     Lowlands-Everett and Vicinity-Lower Chehalis Valley Area-
     Olympics-Seattle and Vicinity-Southwest Interior-Tacoma
     Area-West Slopes North Cascades and Passes-West Slopes
     North Central Cascades and Passes-West Slopes South Central
     Cascades and Passes-Western Skagit County.

PZ...Small Craft Advisory until 10 AM PST Sunday for Grays Harbor Bar-
     West Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 7 PM PST this evening for Admiralty
     Inlet-East Entrance U.S. Waters Strait Of Juan De Fuca-
     Northern Inland Waters Including The San Juan Islands.

     Gale Warning until 7 PM PST this evening 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.

     Small Craft Advisory from 7 PM this evening to 10 AM PST Sunday
     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.

&&

$$