071
FXUS66 KSEW 070338
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
838 PM PDT Wed Aug 6 2025

.SYNOPSIS...Lingering showers and a likely convergence zone
develop behind the passing front tonight into Thursday,
maintaining cooler and cloudier conditions. Showers taper
through the day Thursday, allowing higher pressure to begin to
build and bring a return of warmer and drier conditions.
Stronger high pressure builds overhead around the start of next
week, with much warmer temperatures.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...As the front
pushes eastward, we`ll see some partial clearing over the Puget
sound region and points westward. With modest mid-level lapse
rates and increasing onshore flow, expect some showers this
evening and continued low (10-20%) chances for a few isolated
thunderstorms over the mountains. For the remainder of the area,
breezy winds and a few showers will be the main impact this
evening and overnight.

Showers will linger into Thursday, with a Puget Sound
Convergence Zone developing across the northern and central
Sound providing for a focus for additional showers. Showers
will gradually taper throughout the day, though conditions will
generally remain cooler and cloudier. High temperatures will be
similar to today, only topping out in the 60s along the coast
and upper 60s to low 70s across the interior.

Conditions start to dry out and warm up on Friday as high
pressure builds over the northeastern Pacific and begins to
shift into the region. Onshore flow will continue, allowing for
morning stratus to remain before sunshine in the afternoon. High
temperatures will climb a few degrees from Thursday, mainly
topping out in the mid to upper 60s for the coast and in the 70s
across the interior.

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...High pressure will
continue to strengthen over the area through the weekend,
allowing for temperatures to steadily warm up. Afternoon high
temperatures generally look to top out in the upper 70s to upper
80s across the region by Sunday. Pockets of Moderate (Orange)
HeatRisk are likely on Sunday as a result, mainly for areas
south and southwest of the Sound. The spread in high
temperatures becomes greater heading into early next week, but
ensemble guidance remains in good agreement with respect to a
strong ridge over the region. This will lead to Monday likely
being the warmest day and more widespread Moderate Heatrisk
across the region. Confidence is somewhat lower as there`s a
larger range of possible temperatures for Tuesday and Wednesday
(mostly just how quickly the ridge breaks down and the cooler
air arrives), but the most likely trend is for cooler
temperatures closer to normal values toward midweek. 12

&&

.AVIATION...Westerly flow aloft turning more northwesterly into
Thursday as an upper level trough moves through. Winds are beginning
to start to wind down this evening, through a few gusts remain at
CLM and across portions of the southern Puget Sound area. Winds will
continue to lighten up tonight and remain south to southwesterly.
Winds look to remain less than 8 kt for most areas (except for CLM
and HQM) tomorrow, though winds will slowly become west then
northerly by Thursday evening. Ceilings are a bit of a mixed bag
this evening but mostly VFR to MVFR across the area. Low ceilings
will continue through tonight and through the first half of the day
tomorrow, with widespread MVFR to IFR cigs with localized periods of
LIFR possible, especially along the coast. A convergence zone will
develop and slowly sink southward near PAE, though should remain
north of SEA before dissipating early Thursday morning. Cigs will
slowly lift and scatter throughout the day, with a return to VFR
conditions by late Thursday afternoon.

KSEA...VFR conditions this evening will lower back to MVFR early
Thursday morning and continue into the early afternoon when cigs
slowly lift and scatter through the afternoon. VFR conditions are
expected to return late Thursday afternoon. The convergence zone
should remain north of the terminal, keeping winds
south/southwesterly through tonight and Thursday morning before
slowly turning west then north throughout the day Thursday.

62

&&

.MARINE...A frontal system is passing through area waters this
evening. A SCA remains in effect tonight for the central/eastern
Strait of Juan de Fuca due to westerly winds. High pressure rebuilds
over the waters Thursday and remains in place into the weekend.
Daily westerly pushes for the Strait of Juan de Fuca may require
additional headlines for Thursday and Friday. A thermal trough may
form along the coast over the weekend with stronger NW winds
possible over the Coastal Waters.

Seas will remain around 5 to 7 feet through mid-week period. Seas
ease back to 3 to 5 ft by Friday.

McMillian/62

&&

.FIRE WEATHER...A cold front is progressing across western
Washington this afternoon. Rain showers continue across the
interior and Cascades. Coverage is expected to slowly decrease
to primarily a convergence zone in Snohomish/Skagit Counties
through tonight. Isolated thunder remains a possibility through
the evening. A few of the heavier showers may produce additional
locally heavier amounts in the Cascades of around 0.5".
Additionally, gusty winds in the interior will peak this
afternoon with gusts of 20 to 30 mph. Overall, no impacts are
expected in terms of fire weather with this pattern.

The next elevated fire weather concern is with a hot and dry pattern
moving in late this weekend into early next week, with drier
relative humidities (widespread 30% with a few spots below on
Monday, and warm temperatures with highs in the upper 80s to low
90s).

HPR

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

&&

$$