FXUS66 KSEW 071610
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
910 AM PDT Tue May 7 2024

.UPDATE...No changes to the overall forecast. Cooler, below normal
conditions will trend much warmer into Friday and Saturday -
likely the warmest conditions of the year so far. Please see the
aviation and marine sections below for updates to those forecasts.

&&

.PREV DISCUSSION... /issued 321 AM PDT Tue May 7 2024/

.SYNOPSIS...An upper level trough will exit the region today and
a ridge of high pressure aloft will begin to build into the area
on Wednesday. The upper ridge will 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 minor cooling trend Sunday into Monday.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...The convergence zone had
shifted into King County as of 130 AM PDT this morning and will
continue to gradually shift south and eastward before dissipating
over the Cascades later this morning. A few showers will linger
into the afternoon mainly over the mountains as the upper trough
responsible for the recent cool, wet conditions finally shifts
east of the area. And then the change begins. Upper ridging
offshore begins to build into the area tonight and Wednesday.
Sunshine returns to the area on Wednesday as high temperatures
rebound to near seasonal levels under the influence of the
building ridge.

The upper ridge centered just offshore continues to build on
Thursday as 500 millibar heights approach 580 dam for the first
time since...well, I can't remember when. At the same time,
thermally induced low pressure expanding northward along the
Oregon coast reaches the area. This will turn the low level flow
offshore with coastal areas experiencing a significant boost in
temperature. Hoquiam and Forks should have no problem reaching the
mid 70s (or higher) on Thursday afternoon. Interior areas will
warm up as well...with lower to mid 70s common from the Seattle
area southward.

.LONG TERM /FRIDAY THROUGH MONDAY/...The upper ridge axis shifts
onshore on Friday while the thermal trough remains oriented along
the coast. This will likely be the warmest day for the
coast...with highs reaching the lower to mid 80s...which is daily
record territory. Plentiful sunshine will be found regionwide with
mid 70s to mid 80s across the interior lowlands. Models have the
thermal trough shifting inland by later in the day on Friday.
Coastal areas should see 15 to 20 degrees of cooling for
Saturday, but the thermal trough will produce another warm day for
interior locations. A weak system passing to our north is
expected to dent the ridge Sunday into Monday. Aside from a slight
chance of mountain showers near the Canadian border, conditions
look to remain dry with temperatures in the 60s and 70s...still
above seasonal norms for the time of year. 27

&&

.AVIATION...An upper ridge will build offshore today and continue
through Wednesday with northwesterly flow aloft transitioning more
northerly tonight. Generally a mix of VFR/MVFR cigs this morning,
with MVFR cigs mainly from Skagit to King Counties. A few showers
will linger today, mainly for the interior. VFR cigs expected by the
afternoon with some clearing towards SCT into this evening and
tonight. MVFR cigs may briefly develop for some interior areas early
Wednesday morning. Mostly west/northwest winds.

KSEA...MVFR cigs this morning, improving to VFR near 18-19z. BKN VFR
this afternoon, becoming more SCT later today. MVFR cigs may briefly
develop again Wednesday morning. Light southerly winds will become
northerly around 19z-20z with winds becoming lighter tonight. JD

&&

.MARINE...High pressure over the waters through Wednesday
night. Thermally induced low pressure moving up the coast Thursday
will shift over the inland waters Friday and east of the Cascades
Saturday. High pressure will remain over the outer coastal waters
through Saturday.

Small craft westerly winds in the Strait of Juan de Fuca at times
through Wednesday. Small craft northwesterly winds Admiralty
Inlet tonight.

Seas 10 feet today subsiding to 9 feet tonight and 6 or 7 feet
Wednesday. Felton

&&

.HYDROLOGY...No river flooding expected in the next 7 days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 2 PM this afternoon to 2 AM PDT
     Wednesday for West Entrance U.S. Waters Strait Of Juan De
     Fuca.

     Small Craft Advisory until 2 AM PDT Thursday for Central U.S.
     Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 2 PM PDT Wednesday for East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 6 PM this evening to 2 PM PDT
     Wednesday for Admiralty Inlet.

     Small Craft Advisory until 6 PM PDT 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.

&&

$$