047
FXUS66 KSEW 031112
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
412 AM PDT Wed Jul 3 2024

.SYNOPSIS...Dry and warm conditions continue this week. High
pressure builds and moves over the region late in the week,
bringing very hot temperatures this weekend and into the start of
next week. The hot and dry conditions will also yield elevated
fire weather concerns into the weekend. Some slight cooling is
possible later next week, but temperatures are likely to remain
well above normal.

&&

.SHORT TERM /TODAY THROUGH FRIDAY/...Another round of low clouds
along the coast and portions of the interior this early this
morning. This will scatter toward early afternoon though, with
another mild afternoon featuring abundant sunshine in store today.
High pressure will continue to build over the eastern Pacific and
slowly shift eastward through the next few days. This will lead to
a steading warming and drying of conditions across the region
through the remainder of this week. The initially warm conditions
through the Independence Day holiday will transition to hot by the
end of the week. Expect high temperatures approaching the 90
degree mark for much of the Puget Sound region Friday (with
locally hotter conditions south). This will bring widepsread
Moderate (Orange) HeatRisk levels by Friday.

.LONG TERM /SATURDAY THROUGH TUESDAY/...The continued warm up
looks to peak in magnitude for most of the region over the
weekend. There remains strong agreement in the ensemble guidance
supporting the ridge axis shifting more directly overhead Saturday
and Sunday. While strong offshore winds are not expected, expect
that at least some neutral or slightly offshore wind will
eliminate any inland push of marine air and the very warm air mass
will drive temperatures well into the upper 80s or 90s for much of
the region. The forecast continues to closely trend with the
50th percentile data in the NBM, which remains warmer than the
deterministic NBM for many days/locations. Overnight low
temperatures will hover in the lower 60s for most of the region.
These conditions will result in widespread HeatRisk levels of at
least moderate/orange with some areas (including the urban heat
islands) getting to the Major (red) category. Again, the overnight
low temperatures are within a degree or two of the thresholds that
would chage things from Moderate or Major in many locations so
there may continue to be some fluctuations day to day. However,
it`s worth noting that the temperatures for Sunday (and Sunday
night) have continued to trend upward for the interior. The
potential for several days with high temperatures into the 90s is
increasing, and this level of heat can cause to heat-related
impacts, especially when considering the accumlated effect of heat
and the very mild nights. While some onshore flow will likely
bring some relief to the coast Sunday, this is unlkely to push
deeper into the interior until at least Monday. However,
temperatures are still likely to remain well above normal through
much of next week.

&&

.AVIATION...Upper ridge centered offshore will continue to build
into the region today with northwesterly flow aloft. The low level
flow remains onshore. Low MVFR stratus along the coast will extend
locally inland this morning. Much like yesterday morning, a
stratocumulus deck is gradually filling in across much of the
interior this morning. Ceilings will lower to 2000 to 3000 feet at
times for the interior terminals this morning before scattering and
clearing this afternoon. Stratus along the coast is expected to burn
off 20Z-22Z, but will return by around 06Z tonight.

KSEA...Ceilings lower to 2500 to 3000 feet at times this morning
before lifting and scattering after 18Z. VFR conditions prevailing
this afternoon and evening. Surface winds light S/SW this morning
will veer N/NW 5 to 10 knots by mid afternoon into this evening.

27

&&

.MARINE...Light onshore flow will continue today into Thursday as
1030+ millibar surface ridge remains firmly in place over the
offshore waters. Thermally induced low pressure will expand
northward along the coast Friday and Saturday resulting in weak
offshore flow at times. The thermal trough will shift into the
interior on Sunday for a switch to onshore flow early next week.
Quieter conditions are expected across area waters until late in the
weekend when increasing onshore could necessitate some headlines for
the strait and portions of the coastal waters. 27

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 11 AM PDT this morning for Coastal
     Waters From Cape Flattery To James Island 10 To 60 Nm-
     Coastal Waters From James Island To Point Grenville 10 To
     60 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater 10 To 60 Nm.

&&

$$