214
FXUS66 KSEW 041012
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
313 AM PDT Mon Aug 4 2025

.SYNOPSIS...Cooler and dry conditions with increased cloud coverage
again today as a shortwave moves across Western Washington. Upper
level troughing will persist Tuesday through Thursday, with a
frontal system bringing widespread precipitation to the area.
Conditions will dry out and become warmer into the weekend as an
upper level ridge builds over the Pacific Northwest.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY/...While at first glance the
current satellite imagery does not seem to differ much from 24 hours
ago, with a wide distribution of clouds over W WA, latest obs show
these to be mainly mid level clouds or, at the most pessimistic,
high-end low clouds. This has managed to keep temperatures a degree
or two warmer than Sunday morning at this time, which inherited
forecast picked up pretty well on. This slight nudge upward will be
present also in high temps this afternoon.

Models remain consistent shifting a dry shortwave trough eastward
over the area today, once again helping to keep temps mild. A
shortwave ridge building to the east, centered over N ID/W MT, may
allow for a slight increase in high temps Tuesday...but most
attention will be focused to the west, where a more organized front
will approach the coastline Tuesday afternoon and evening associated
with an upper level low centered off the Canadian coast...a little
bit north of Vancouver Island. Progs remain on track bringing these
conjoined features eastward through the day on Wednesday...although
some are backing away from just how organized this feature may be.
This is not enough to deter from the forecast of widespread
precip...however, it does call into question the thunderstorm
threat. Guidance continues to shave away at the forecasts from
previous runs...while the threat is not entirely eliminated from the
CWA, the window continues to be pared down to late Wednesday
afternoon/early Wednesday evening. The threat itself also starts to
find itself boxed in...constrained to the eastern half of the CWA
during the aforementioned window with any lingering storms later on
in the evening likely to be relegated to the North Cascades. As one
would expect from the FROPA, high temps Wednesday will take a little
tumble, but ultimately not too different from what was seen
yesterday or what is expected for today.

.LONG TERM /THURSDAY THROUGH SUNDAY/...Models vibing better when it
comes to the track of the upper level low...although not completely
in lockstep. Still, this strained consensus lends more confidence to
post frontal showers extending into much of the morning Thursday
before the gradual drying up from west to east. Dry conditions are
expected to resume Thursday night.

Models largely remain in agreement from this point to the conclusion
of the long-term forecast, with upper level ridging building over
the Pacific NW...bringing with it a warming trend that promises a
return to more summer-like temperatures. Highs Friday generally
ranging in the mid 70s to around 80 for the interior, upper 60s near
water, while Saturday sees upper 70s to mid 80s for the lowlands,
right around 70 for water-adjacent locations. Highs for Sunday show
this trend continuing...lower to mid 70s near water but lower to mid
80s for the interior.

18

&&

.AVIATION...Weak troughing over the Pac NW today with light wind
aloft. Near the surface, low level onshore flow prevails with
stratus clouds and MVFR to IFR conditions over the lowlands. Low
clouds lifting and slowly scattering by 21-00z. MVFR to IFR
conditions returning overnight. Rain will reach the coast Tuesday
afternoon as a weak frontal system moves in. 33

KSEA...Low clouds and MVFR conditions this morning, with low clouds
burning off after 21z. SW winds around 5-8 kt. 33

&&

.MARINE...Onshore flow prevails through Monday with high pressure
off the coast and lower pressure inland. Highest wind and waves will
be found through the Strait of Juan de Fuca. A weak frontal system
will cross the waters Tuesday and Wednesday. High pressure will
rebuild over the waters Thursday and Friday. A thermal trough may
form along the coast over the weekend with stronger NW winds over
the Coastal Waters. 33


&&


.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 AM PDT early this morning for
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 5 PM this afternoon to 5 AM PDT
     Tuesday for Central U.S. Waters Strait Of Juan De Fuca-East
     Entrance U.S. Waters Strait Of Juan De Fuca.

&&

$$