Renton, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

593
FXUS66 KSEW 211000
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
300 AM PDT Wed May 21 2025

.SYNOPSIS...Cool and unsettled conditions will continue through
Thursday under the influence of troughing. A cooling and warming
trend will settle into western Washington Friday into much of the
weekend as high pressure amplifies northward. Precipitation
chances increase into early next week with continued above-normal
temperatures.

&&

.SHORT TERM /TODAY THROUGH FRIDAY/...While a majority of shower
activity has tapered off early this morning, steady convergence
zone showers continue over the Puget Sound and eastward over King
and Snohomish Counties. Showers will slowly taper off throughout
the morning across western Washington, with low stratus making for
another cool and damp morning. Conditions will dry out throughout
the day, but cloudy skies will limit temperatures into the upper
50s to mid 60s.

A trough axis will shift inland later this evening, spreading
another round of light showers eastward. While a majority of the
moisture associated with this system will stay to our south, areas
generally south of the Puget Sound and over the Cascades will see
some light rain accumulations late Thursday into Friday. Showers
will taper off over the Cascades by Friday evening as zonal flow
develops aloft, with temperatures returning to near-normal in the
mid to upper 70s for most interior lowlands.

.LONG TERM /SATURDAY THROUGH TUESDAY/...A high pressure ridge
building over the western US will amplify northward on Saturday
and Sunday, allowing for warmer and drier weather to settle into
western Washington. Sunday is on track to be the warmest day of
the period, with temperatures peaking in the upper 70s across the
interior lowlands. Areas along the Cascade foothills and valleys
could see highs once again in the lower 80s.

Forecast models continue to show large differences heading into
early next week, with potential for a frontal system to bring
showers and cooler conditions to the region as early as Monday.
However, this will depend on how persistent the ridge stays into
early next week. A chance of showers has been maintained through
Tuesday with continued above-normal temperatures.

15

&&

.AVIATION...Northwesterly flow will persist aloft today before
gradually transitioning to more southwesterly tonight into
Thursday as a weak upper level trough swings across the region.

Radar this morning shows a convergence zone lingering across the
central Sound, which has been responsible for bringing shower
activity and localized lower ceilings to terminals like KPWT and
KPAE over the past several hours. Expect overall shower activity,
including showers associated with the PSCZ, to gradually taper
throughout the morning hours. Ceilings this morning have generally
remain a mixed bag of VFR and MVFR across the region, however
expect a more widespread drop to MVFR ceilings for central and
northern Sound terminals over the next few hours. Improvement to
VFR ceilings likely between 18-20Z, with conditions likely to
remain VFR through the remainder of the day.

Southerly surface winds at 4-7 kts for interior terminals will
transition to northerly at 4-9 kts, likely between 17-20Z.

KSEA...MVFR ceilings, with ceilings expected to improve towards
VFR by late morning (17-20Z). S/SW surface winds persisting at
4-7 kts this morning will transition to the N/NW between 17-19Z,
increasing this afternoon to 7-10 kts.

14

&&

.MARINE...High pressure over the area waters this morning will
weaken slightly as a surface low tracks towards Oregon/N
California today. Winds will ease through the morning hours, with
a slight uptick in northwesterlies (10-15 kt) expected across the
coastal waters this afternoon. Seas across the coastal waters
remain between 7-9 ft this morning and will continue to fall to
4-6 ft throughout the day.

High pressure will build back into the area waters on Thursday and
remain the dominant influence across the waters through the
weekend. This will continue to promote northwesterlies across the
coastal waters and diurnal onshore pushes through the Strait of
Juan de Fuca at times over the next few days. A weak front does
look to approach the region on Friday, but looks to dissipate
before reaching the area waters for no significant impacts at this
time. The next frontal system looks to move into the area waters
by early next week. Seas across the coastal waters will persist
at 4-6 ft into early next week.

14

&&

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

$$