458
FXUS66 KSEW 280310
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
811 PM PDT Fri Jun 27 2025

.UPDATE...Some lingering showers over northern portions of the CWA
this evening, but for the most part activity is winding down. Clouds
overnight will give way to clearing by Saturday afternoon. Inherited
forecast remains on track. No evening update planned.

&&

.SYNOPSIS...An upper level ridge will build into the area tomorrow
for more sunnier skies. Monday will likely be the warmest day of
the week, before the ridge slides east and another midweek trough
moves in and cools things down.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...A ridge will build into the
area over the weekend, leading to sunnier skies and highs in the
low 70s on Saturday, climbing to the upper 70s and low 80s on
Sunday. Northwesterly onshore flow will prevail through the
weekend. Monday is likely to be the warmest day of the week, with
highs in the mid to upper 80s, and even around 90 in the Cascade
valleys and Chehalis Valley. Overnight lows will be around 59 to
60 degrees. HeatRisk for Monday will be orange (Moderate) for
areas of Puget Sound from King county south to Thurston and Mason
Counties, as well as the Cascade valleys.

With the heat on Monday, there is likely to be elevated fire
weather concerns as minimum relative humidity values may be as low
as the mid 20 percent range, especially in the Cascades and
adjacent foothills. Recent rainfall has aided the grasses and finer
fuels, but these are the fuels that are most receptive to heat
and drying on a smaller timescale. Use caution in areas of dry
grasses.

.LONG TERM /TUESDAY THROUGH FRIDAY/...Temperatures cool off by a
few degrees on Tuesday, but widespread 80s are still in the
forecast. It won`t be until at least Wednesday when the next
shortwave trough moves through the area and brings things back to
the mid to upper 70s with some morning cloud cover. Similar
temperatures are expected through Friday. There is some
uncertainty in the ensembles regarding the Independence Day
forecast, with some clusters favoring an incoming trough, others
favoring a ridge. More details will be known in the coming days.

21

&&

.AVIATION...Zonal flow aloft becoming northwesterly by Saturday
morning. Surface winds largely south to southwesterly at 4-8 kts.
PAE stands out as the only terminal experiencing northerly winds,
but speeds remain similar.

Widespread VFR conditions persist with some isolated
MVFR spots. Another round of low stratus expected to impact the
terminals Saturday morning, bringing down ceilings to MVFR for the
majority of terminals. Guidance hints at a 20-50% chance of IFR
along the coast (highest chance), Kitsap Peninsula, and north Puget
Sound. VFR conditions will return Saturday afternoon after 20z-22z.
Winds will become northerly Saturday afternoon.

KSEA...VFR conditions this afternoon at the terminal will
deteriorate Saturday morning to MVFR. Improvement into VFR is
expected Saturday afternoon after 20-21z. Southwesterly winds this
afternoon. Winds may attempt to become W/NW between 4z-9z, however
the most probable scenario will be winds becoming more WSW at around
240-260 degrees. Winds will become northwesterly Saturday afternoon
(18z-20z) at 6-7 kt. 29/18


&&

.MARINE...Surface high pressure will build over the coastal waters
and persist into the weekend, establishing northwesterly onshore
flow. This high pressure will weaken slightly on Monday, but remain
the dominant feature next week. Westerly pushes across the Strait of
Juan de Fuca will occur each evening with varying strength. Majority
of the westerly pushes look to remain below small craft criteria at
this time. However, the pushes on Tuesday and Wednesday may meet
small craft criteria thresholds. Seas this weekend will build to 4-6
ft and will increase to 5-7 ft on Monday. Seas will decrease Tuesday
morning and remain at 3-4 ft throughout the week. 29/18


&&

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

$$