216
FXUS66 KSEW 041553
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
853 AM PDT Tue Jun 4 2024

.SYNOPSIS...The next frontal system associated with the
atmospheric river event will move across the region this morning,
bringing another round of rain and gusty winds to western Washington.
Showers will continue in its wake, but will taper tonight into
Wednesday. Drier and warmer conditions are expected the second
half of the week as upper level ridging builds across the West. A
weak trough moving across the area may bring some showers to the
mountains Sunday into Monday.

&&

.UPDATE...Generally light precipitation associated with the
second, weaker atmospheric river is moving across the region this
morning. Rain rates have been relatively light and additional
flooding now appears unlikely. Winds remain elevated this morning.
Winds peaked earlier this morning across the Washington Coast and
are peaking between now and 10am this morning for the interior.
Precipitation will taper off today. The rest of the forecast
detailed below is on track is and no additional updates are
planned this morning. -Wolcott-

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...The next frontal system
associated with the atmospheric river event will move across
western Washington this morning, with radar already showing the
next round of rain pushing into the interior. Overall, do not
expect conditions to be as wet as they were with the previous
system. The heaviest rainfall will be in the mountains, where an
additional 1-2 inches will be possible through the day. Additional
totals along the coast through tonight generally remain between a
quarter of an inch to half an inch and can range from a few hundredths
of an inch to half an inch across the interior lowlands. Isolated
thunderstorms will be possible as well, so locally higher amounts
will be possible in any convective showers. Latest hi-res guidance
does hint at a relatively short-lived convergence zone developing
across the northern Sound in the wake of the front later this
morning. Rain will then taper to showers this afternoon and
evening. In addition to precipitation, southerly winds will also
remain gusty through the morning hours, with winds generally
persisting at 15 to 25 mph, and gusts up to 40 mph possible. Winds
gradually look to decrease again by the late morning hours. Showers
will continue to taper region-wide by tonight and afternoon high
temperatures will generally be in the low 60s.

An upper level ridge will then start to build across the West
Wednesday into Thursday, bringing warmer and drier conditions to
the region the second half of the week. Skies will clear out on
Wednesday for some sun and afternoon high temperatures will
rebound closer to normal - topping out in the upper 60s to low 70s
in spots. With the upper ridge strengthening on Thursday, expect
temperatures to climb a few more degrees and to top out in the
upper 60s to mid 70s for the majority of the area.

.LONG TERM /FRIDAY THROUGH MONDAY/...Both deterministic and
ensemble guidance indicate upper level ridging influencing the
Pacific Northwest headed into the weekend. The ridge axis will
then gradually move inland and push east on Saturday, opening the
door for a weak shortwave trough to traverse the region on
Sunday. Friday and Saturday currently look like the warmest days
of the long term, with temperatures expected to climb into the
upper 70s to low 80s across the area. Heat risk generally expected
to remain in the minor category for the majority of western
Washington for now, though could see some isolated spots of
moderate primarily along the Cascade valleys on Friday- where
temperatures could reach the mid to upper 80s. A weak trough will
then move across the area on Sunday. At this time, guidance does
not indicate much in the way of precipitation outside of a few
showers in the mountains. However, can expect cloudier conditions
and for highs to cool a few degrees on Sunday. Light showers may
linger across the higher terrain into Monday. 14

&&

.AVIATION...Stronger westerly flow aloft will continue through today
with an upper trough over British Columbia. CIGs have been primarily
MVFR (although IFR/LIFR has impacted PWT and PAE). Light showers
continue to move across the region as a couple fronts move through
today. Mist/fog may accompany the lower ceilings/showers at times
(given the warm air advection). Still looking at improvements in
cigs to BKN MVFR/VFR this afternoon. There remains a chance of
convective showers this afternoon with a slight chance of
thunderstorms, mainly King County northward and into the Cascades.
Breezy southerly winds this morning with gusts ranging 20 to 35 kts,
with winds becoming more W/SW this afternoon, and decreasing to no
more than 20 kt

KSEA...MVFR CIGs this morning before improvements to BKN VFR later
this afternoon. Small possibility of IFR this morning (mainly
between 16-18z with mist), but confidence remains low. Otherwise,
showers at times through the early afternoon. Breezy southerly winds
gusting to 25 to 35 kts through this morning becoming more SW this
afternoon and easing a bit into this evening.

JD/HPR

&&

.MARINE...A strong front will move across the area through this
morning with additional stronger winds for the waters. Gale force
southerly winds are expected at times for the Coastal Waters, as
well as eastern Strait of Juan de Fuca, Admiralty Inlet, and
northern inland waters through this morning, and into the afternoon
(have extended the hazards in place through 00Z). Southerly winds
will also remain breezy for Puget Sound as well. Winds will become
more southwesterly midday through the afternoon and slowly ease for
most waters. A westerly push is expected through the Strait of Juan
de Fuca this afternoon into this evening for additional SCA winds in
this area. High pressure will then build Wednesday and remain over
western Washington into the weekend for a less active weather
pattern.

Seas of 8 to 11 feet today will build towards 12 to 15 feet tonight
into Wednesday morning. Seas will slowly subside below 10 feet on
Thursday, but breezy northerly winds are expected over the Coastal
Waters late week into the weekend.

JD/HPR

&&

.HYDROLOGY...Rain rates with this second round of precipitation
have been below concerning thresholds and the forecast going
forward does not give indication that additional flooding is
likely. As such the Flood Watch has been cancelled. Rivers will
continue to run cool and fast this week despite warm and dry
conditions late this week into the weekend. -Wolcott-

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory until 11 AM PDT this morning for Admiralty Inlet
     Area-Bellevue and Vicinity-Bremerton and Vicinity-Central
     Coast-East Puget Sound Lowlands-Eastern Strait of Juan de
     Fuca-Everett and Vicinity-Hood Canal Area-Lower Chehalis
     Valley Area-North Coast-San Juan County-Seattle and
     Vicinity-Southwest Interior-Tacoma Area-Western Skagit
     County-Western Strait of Juan De Fuca-Western Whatcom
     County.

PZ...Small Craft Advisory until 5 PM PDT this afternoon for Puget
     Sound and Hood Canal-West Entrance U.S. Waters Strait Of
     Juan De Fuca.

     Small Craft Advisory until 11 PM PDT this evening for Central
     U.S. Waters Strait Of Juan De Fuca.

     Gale Warning until 5 PM PDT this afternoon for Admiralty Inlet-
     East Entrance U.S. Waters Strait Of Juan De Fuca-Northern
     Inland Waters Including The San Juan Islands.

     Small Craft Advisory from 5 PM this afternoon to 11 PM PDT this
     evening for East Entrance U.S. Waters Strait Of Juan De
     Fuca.

     Small Craft Advisory until 5 AM PDT Wednesday 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.

&&

$$