490
FXUS66 KSEW 120941
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
241 AM PDT Mon Aug 12 2024

.SYNOPSIS...Upper level troughing over the region will promote
onshore flow and cooler temperatures the next several days.
Isolated thunderstorms will be possible across the North Cascades
today and Tuesday. More widespread chances of precipitation may
return to western Washington by the weekend.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY/...Troughing over the Pac NW
will keep western WA mostly cloudy and cool over the next several
days. No signs of the aurora from NWS Seattle overnight due to the
cloud cover, but others were lucky with a few breaks. The focus
for today will be showers and possible thunderstorms over the
North Cascades once again, especially near the crest. There are
some nocturnal showers near the crest early this morning but we
should see activity increasing this afternoon and evening.
Elsewhere, the coast may see a little light rain this morning
under the stratus layer. Temperatures will track a few degrees
cooler than average with highs in the 60s to lower 70s.

The trough makes little progression on Tuesday and we`ll continue
to see onshore flow and cloudy/cool weather. There`s another
threat of showers and thunderstorms near the crest in the North
Cascades.

The trough exits east on Wednesday and we`ll see higher heights
and slightly warmer conditions over western WA. Interior
temperatures will reach the mid to upper 70s - just a degree or
two shy of normals. NW winds will keep the coast in the 60s. 33

.LONG TERM /THURSDAY THROUGH SUNDAY/...An upper level low will
drop down from Canada and spin offshore as we move though the
latter half of the week. Onshore flow will be lighter, for the
most part, and we should see more sunbreaks during the afternoon
and early evening hours. Temperatures stick in the 60s and 70s
with lows in the 50s. Showers (and possible thunderstorms) are
expected in the mountains both Thursday and Friday. Shower
coverage expands to all of western WA over the weekend as the low
pulls in additional moisture. 33

&&

.AVIATION...Upper-low overhead with variable winds aloft. MVFR and
low-end VFR stratus is increasing in coverage early this morning.
This trend will continue before gradually decreasing in coverage as
the day progress. A return to more widespread VFR is likely after
the 21z time frame but there`s an isolated chance of some locations
not improving at all. However, widespread stratus is certain to
redevelop Monday night into Tuesday morning. Surface winds winds
will remain west-southwesterly 5 to 10 kt throughout the TAF
period.

KSEA...Low-end VFR to MVFR cigs have been observed so far this
morning. A gradual improvement to mostly VFR is expected as the day
progress (after 21z). Winds remain southwesterly 5 to 10 kt. More
stratus is slated to return Monday night into Tuesday morning.

McMillian

&&

.MARINE...Broad high pressure over the East Pacific will continue
onshore flow over the area waters. Diurnally driven pushes down the
Strait of Juan de Fuca will occur each evening with no signs of SCA
level winds for the next few days. Seas are to range between 3 to 6
feet throughout much of the upcoming week. Can`t rule out visibility
restrictions at times with the possibility of mist squeezing out of
marine stratus.

McMillian

&&

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

$$