037
FXUS66 KSEW 281539
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
839 AM PDT Sat Jun 28 2025

.SYNOPSIS...Upper level high pressure builds over the region
through the day, bringing increased sunshine and warmer
conditions. This ridge remains in place through the start of
next week, with Monday likely the warmest day for most. The
ridge slide eastward around Tuesday, with another disturbance
arriving around midweek.

&&

.UPDATE...Quite a bit of cloud coverage still to clear out this
morning across the region. Still on track for clearing skies this
afternoon and a sunny weekend, with temperatures warming up. There
are no major changes to the forecast below (except for the
aviation section).

HPR

&&

.SHORT TERM /TODAY THROUGH MONDAY/...High pressure begins to
build overhead later today, bringing a shift to a warmer and dry
pattern across the area this weekend and into the start of next
week. Some lingering patches of fog or low clouds remain in
parts of the lowlands this morning, but expect these to clear
through the day. For the weekend, temperatures top out in the
upper 70s to lower 80s inland, with a Minor HeatRisk across the
region. With the ridge overhead and perhaps some light offshore
flow, expect that Monday will be the warmest day across the
area with temperatures into the mid to upper 80s. A few of the
warmest spots could reach 90. This will lead to a corridor of
Moderate (Orange) HeatRisk extending from around Seattle through
Tacoma as well as east into the Cascade valleys. In addition to
the heat concerns, expect that daytime RH values will dip into
the 25-35% range. Despite some recent rain, some of the grasses
other fine fuels likely will dry out in this stretch and could
elevate fire weather concerns for the start of next week.

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...Expect some slight
moderation in temperatures with the ridge shifting eastward and
an eventual return to cooling onshore flow, but it may not be
early or fast enough to prevent another day with temperatures
climbing into the 80s inland. This could maintain a second day
of Moderate HeatRisk in the greater Seattle area and extending
eastward into the foothills and Cascade valleys. While ensemble
guidance does depict a wider array of possible outcomes from
around midweek onward, the most likely scenario remains the
influence of the next disturbance sliding across the region
around Wednesday. This will bring a boost in cloud cover and
knock afternoon high temperatures down to the 70s. Confidence
remains low into the later portions of next week with the
evolution of the pattern.   12

&&

.AVIATION...An upper level trough will shift east of the region this
morning and an upper ridge will begin to build across the area with
northwest flow aloft. Light surface flow will turn northerly this
afternoon. A mixed bag of mostly VFR/MVFR ceilings this morning will
lift to primarily VFR by around 20Z-21Z this afternoon then
eventually scatter out areawide this evening.

KSEA...MVFR deck this morning then lifting back to VFR this
afternoon and scattering out this evening as subsidence with upper
ridging takes over. Surface winds light and variable this morning
will become northerly this afternoon and rise to 7 to 10 knots
near or after 00Z. 33/27

&&

.MARINE...Surface ridging over the coastal and offshore waters
will remain in place into early next week while thermally induced
low pressure expands northward across the interior. This will
gradually increase northwesterly onshore flow across the coastal
waters by later in the weekend. Diurnal driven westerly pushes in
the strait will increase early next week...potentially reaching
small craft advisory levels later Monday and near gale Tuesday in
the central and east portions of the strait. 27

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&

$$