382
FXUS66 KSEW 271107
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
407 AM PDT Sat Jul 27 2024
.SYNOPSIS...A weak upper level trough remains over the region
through the weekend. A passing front Monday will bring widespread
rain chances to the area, with showers lingering into Tuesday as
the upper trough moves through. Weak high pressure aloft begins to
build again toward midweek for a warming trend late next week.
&&
.SHORT TERM /TODAY THROUGH MONDAY/...Onshore flow continuing this
morning with some patches of low stratus evident near the coast,
along the Strait of Juan de Fuca, and through the lower Chehalis
valley toward southern Puget Sound. With the weak upper trough in
place over the region, not expecting much change in the pattern
into the weekend. Onshore flow will persist and mostly dry
conditions continue, though an embedded disturbance may be enough
to bring a few light showers in the mountains this afternoon or
evening. Chances will be best in the far North Cascades close to
the crest, and can`t totally rule out an isolated lightning strike
or two. Otherwise, temperatures holding close to normal for this
time of year with some morning clouds and abundant afternoon
sunshine. and not much change through Sunday.
A stronger frontal system is then expected to approach by Monday
with a relatively (for this time of year) impressive tap of
moisture spreading into the region with it. Expect fairly
widespread measurable rain with this frontal system, but amounts
generally around a tenth of an inch or less for the lowlands.
Meanwhile, around a 50% chance for portions of the Olympics and
Cascades to see a wetting rain of at least 0.25 inches of rain on
Monday. With this cooler weather system crossing, expect to see
temperatures only topping out in the upper 60s. 12
.LONG TERM /TUESDAY THROUGH FRIDAY/...Expect some showers to
linger into Tuesday as the upper trough shifts eastward. Ensembles
continue to suggest a return of high pressure over the region by
around midweek, with a return of above normal temperatures for
the late stages of next week, as temperatures in the interior
climb into the 80s and a drier pattern returns. This will bring a
return of some areas of Moderate HeatRisk in the interior for the
later stages of next week. 12
&&
.AVIATION...Northwesterly flow aloft as a weak upper level trough
remains over the area. VFR early this morning across most area
terminals, the exception being KHQM where marine stratus has
already started to spread inland, deteriorating conditions down to
MVFR/IFR. Latest guidance suggests stratus will intrude through
KOLM but will likely not push past that. MVFR/IFR ceilings will
burn back towards the coast by the afternoon (18z), with a 40%
chance that KHQM stays socked in all day with stratus. Elsewhere,
VFR will persist through the remainder of the day.
KSEA...VFR early this morning. N/NE winds will turn more W/SW late
this morning and generally be around 4 to 8 knots. Latest guidance
suggests a 20% chance of MVFR conditions early this morning
(12z-16z) depending if stratus reaches the terminal. At this
time, looking less likely that stratus will reach that far, but
cannot rule it out. Otherwise, VFR will persist for the remainder
of the day.
Mazurkiewicz
&&
.MARINE...Surface high pressure remains offshore with lower
pressure inland. Marine stratus this morning will likely create
visibility restrictions in mostly all of the exterior water zones,
along with the Strait of Juan De Fuca.
Low level onshore flow will increase later on this evening, with a
small craft advisory in effect for the Central and Eastern Strait
of Juan De Fuca for increased westerlies. A frontal system looks
to transverse the waters early next week, but guidance still shows
no threat of winds being above any threshold.
Coastal seas 4 to 6 feet will continue throughout the rest of
Saturday, before easing to 3 to 5 feet on Sunday and generally
remaining that way throughout the week.
Mazurkiewicz
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 5 PM this afternoon to 2 AM PDT Sunday
for Central U.S. Waters Strait Of Juan De Fuca-East
Entrance U.S. Waters Strait Of Juan De Fuca.
&&
$$
NWS SEW Office Area Forecast Discussion
Discussion Script by Ken True at Saratoga Weather - WFO Script by SE Lincoln Weather
