Washington State Forecast Discussion

Western Washington


928
FXUS66 KSEW 081529
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
829 AM PDT Wed May 8 2024

.UPDATE...High pressure will build inland through the rest of the
week and into the weekend, kicking off a warming trend. The
lowlands are on track to see temperatures in the 80s on Friday and
Saturday with elevated overnight lows in the low to mid 50s. While
air temperatures will be warm, water temperatures will still be
cool enough to pose a safety risk. No updates to the forecast.

&&

.SYNOPSIS...A ridge of high pressure aloft will begin to build
into the area today then strengthen toward the end of the week as
thermally induced low pressure near the surface expands northward
into the area. Dry conditions will prevail along with the warmest
temperatures of the year thus far on Friday and Saturday. A weak
system passing to the north of the area will bring a cooling
trend early next week.

&&

.SHORT TERM /TODAY THROUGH FRIDAY/...Ridging at the surface and
aloft is building into the region today. With plenty of sunshine
today, temperatures will bounce back to near climatological
norms. The upper ridge continues to strengthen on Thursday as low
level northerly flow turns offshore in response to thermally
induced low pressure expanding northward along the coast. High
temperatures will warm several degrees on Thursday...especially
along the coast where offshore flow will boost temps into the mid
70s to near 80. 70s will be common across interior areas from the
Seattle area southward.

The upper ridge weakens slightly on Friday, but 500 millibar
heights remain in the vicinity of 580 dam. Coastal areas are likely
to see another round of warm temperatures before the sea breeze
kicks in late and the thermal trough makes the jump inland.
Friday will be the warmest day thus far this year for much of the
interior lowlands with 70s in the north interior and 80+ from the
Seattle area southward.

.LONG TERM /SATURDAY THROUGH TUESDAY/...A switch to onshore flow
on Saturday will cool coastal areas some 15 to 20 degrees or so
compared to Friday while interior areas remain warm with the
thermal trough in place. Sunday and beyond, the ridge is expected
to flatten as a couple of systems pass by to our north. The main
effect will be to cool temperatures back to near or slightly above
seasonal levels. With the exception of a few possible showers in
the North Cascades, the remainder of the area looks to remain on
the dry side. 27

&&

.AVIATION...Northerly flow aloft as ridging begins to build
offshore and continues through the end of the week. An area of MVFR
stratus extends from Skagit/Snohomish Counties towards the Cascades
this morning, with patchy fog in river valleys, particularly the
Chehalis River Valley. Otherwise, mainly VFR across the area.
Stratus and fog in these areas will clear through the morning with
mainly clear skies this afternoon into the evening. Lighter
northerly winds will increase this afternoon.

KSEA...VFR today with mostly clear skies. There remains a slight
chance for a brief period of MVFR stratus between 16-18z. NE winds
this morning will transition more N around midday, and increase
towards 7 to 12 kts into this evening, before becoming NE again
later this evening. JD

&&

.MARINE...High pressure will continue to build over the waters
today, with a thermally induced area of low pressure moving up the
coast, and advancing inland Friday. Westerly winds will increase
again this afternoon into this evening for the central Strait of
Juan de Fuca with a Small Craft Advisory in place. In addition, a
SCA has been issued for the central and southern inner coastal
waters this afternoon into this evening. Increasing northerly winds
during this period will allow for gusts near 25 kt before winds
slowly subside later tonight. Otherwise, primarily northerly winds
through late week.

Seas of 5 to 8 feet will continue into the weekend. JD

&&

.HYDROLOGY...The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated as needed.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 2 AM PDT Thursday for Central U.S.
Waters Strait Of Juan De Fuca.

Small Craft Advisory until 8 AM PDT this morning for Admiralty
Inlet-East Entrance U.S. Waters Strait Of Juan De Fuca.

&&