Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
745
FXUS66 KSEW 221034
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
334 AM PDT Mon Jun 22 2026
.SYNOPSIS...
Upper level ridge offshore moving over the area tonight into
Tuesday. The ridge will shift east Wednesday. Thermally induced
surface trough developing along the coast today moving inland
Tuesday night and east of the Cascades Wednesday morning. Very
warm temperatures over the interior the next three days. Much
cooler Thursday with low level onshore flow. First weather
system in two weeks moving through Friday. Upper level low
moving over Western Washington Saturday will move east Sunday.
&&
.SHORT TERM /TODAY THROUGH WEDNESDAY/...
Satellite imagery shows low stratus along the coast, moving down
the Strait of Juan de Fuca to near Whidbey Island and over the
Lower Chehalis Valley at 3 am/10z. Just some high clouds over
the remainder of the area. Temperatures were in the upper 40s to
near 60.
Stratus will not move much further inland and dissipate later
this morning. Upper level ridge centered offshore moving east
today while a thermally induced surface trough develops along
the coast. Low level flow turning offshore warming high
temperatures up to mostly the 80s. A few places near the water
will stay in the upper 70s.
Upper level ridge moving overhead tonight and Tuesday while the
thermally induced surface trough remains over Western
Washington. Low level offshore flow continuing producing a mild
morning, lows in the 50s and lower 60s, and a very warm day with
highs in the 80s and lower 90s. Most locations falling just a
couple of degrees short of a record high. The best chance for a
record breaking high will be at Bellingham (record 82 set in
1992).
Upper level ridge weakening Tuesday night with the ridge axis
moving east Wednesday. Thermally induced surface trough moving
inland Tuesday night and east of the Cascades Wednesday. 850 mb
temperatures cooling to plus 14C to plus 16C by Wednesday
afternoon with the winds from 850 mb down to the surface turning
westerly Wednesday morning. All these variables add up to a
weak marine push for the interior with high temperatures
dropping 5 to 10 degrees versus Tuesday readings, into the mid
70s to mid 80s. More cooling along the coast with highs in the
mid 60s. It will be another mild morning with light flow in the
lower levels. Lows Wednesday morning in the mid 50s to lower
60s.
Moderate HeatRisk over all but the coastal beaches today and
Tuesday. There is a small chance, 10 to 20 percent, of major
HeatRisk Tuesday between Seattle and just south of Olympia.
Moderate HeatRisk confined to the Central and Southern Puget
Sound and Cascade foothills Wednesday. A heat advisory will go
into effect today at 11 am/18z until 11 pm/06z Tuesday evening
for all lowland locations except the coastal beaches. The area
under the heat advisory will decrease Wednesday with Northwest
Washington getting dropped from the advisory. The heat advisory
for all areas will come to an end at 11 pm/06z Wednesday
evening. Felton
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Models remaining consistent with much cooler temperatures
Thursday due to low level onshore flow and an approaching
frontal system. Front moving through Western Washington Friday
morning through midday. Rain starting on the coast as early as
Thursday afternoon spreading inland Thursday night. Rain
changing to showers behind the front Friday afternoon. Post
frontal convergence zone possible over Snohomish and Skagit
county Friday afternoon into Friday evening which could leave
the Seattle metro dry. Upper level low moving down from the
northwest over the top of the area Saturday keeping showers in
the forecast. Low kicking out to the east Saturday night making
for a dry but mostly cloudy and cool Sunday.
There is a good chance that even though Thursday and Friday will
be only the 4th and 5th day that it has rained this month in
Seattle, the rainfall from this system will put Seattle above
normal for rain in June. The monthly normal is 1.45 inches.
Current rain total for the month is 1.24 inches.
Highs Thursday in the 60s and lower 70s, Friday in the mid 50s
to lower 60s, Saturday in the lower to mid 60s and Sunday in the
60s. After getting close to record highs Tuesday, it is possible
we could set some record low maximums Friday. The record low
maximum for Seattle Friday is 62 degrees set in 1999. Felton
&&
.AVIATION...
VFR across the majority of the terminals, with the exception of the
coast and Strait of Juan de Fuca, where stratus is bringing LIFR
cigs. Onshore flow continues to push the marine stratus through the
Strait of Juan de Fuca and is starting to spill into portions of
Puget Sound. Latest guidance continues to suggest that the stratus
will not make it to Puget Sound terminals. Improvement expected
later this afternoon for widespread VFR conditions. Another round of
low ceilings expected along the coast after 03z, with moderate
chances (40-55%) for MVFR/IFR cigs and 30-40% chance for LIFR cigs.
Breezy northerly winds will develop this afternoon along Puget Sound
terminals with moderate chances (30-50%) for gusts up to 15-20 kt.
KSEA...VFR conditions today. Stratus continues to sink south along
Puget Sound this morning, but not expecting it to make it to the
terminal this morning, with probabilities of MVFR cigs at 10% or
less. Breezy NW winds will develop this afternoon after 18z, turning
NE in the evening with sustained speeds of 10-12 kt and gusts to 15-
18 kt. NE winds will subside late this evening to 4-6 kt.
29
&&
.MARINE...
High pressure will remain over the waters for the majority of the
week. It will start weakening on Thursday in the wake of an
approaching cold front. The front is expected to move over the
waters on Friday and an additional front on Saturday. High pressure
will rebuild again over the waters on Sunday.
Breezy conditions will develop over Puget Sound this evening through
Thursday morning. However, winds are expected to remain below small
craft thresholds. Strong northwesterly winds over the Strait of
Georgia will also bring breezy conditions to the northern interior
waters Tuesday morning and may see an occasional gust to 21 kt.
Winds will also increase over the outer coastal waters on Tuesday
with a 40-70% chance of small craft winds. Westerly pushes through
the Strait of Juan de Fuca will continue throughout the week.
Guidance has been consistent with Wednesday being the strongest
push, with a 75-95% chance of small craft winds and 25-35% for
gales. A weaker push will follow on Thursday, with latest
probabilities around 35-55% of small craft winds. The chances for
gales on Thursday has trended downwards and latest guidance
suggesting a 5% chance or less. The frontal systems on Friday and
Saturday will also bring additional chances (50-80%) for small craft
winds for the coastal waters and Strait of Juan de Fuca.
Seas will remain below 10 ft through Tuesday, before building to 7-
10 ft on Wednesday. Seas will then decrease below 10 ft on Thursday
and will build to 10 ft Friday with the incoming frontal system. In
addition, seas may get steep at times this week over the coastal
waters.
29
&&
.FIRE WEATHER...
High pressure aloft combined with a thermally induced surface trough
over the area will create elevated fire conditions through
Tuesday. In addition to the warm, dry, and conditionally
unstable air mass, low level offshore flow will drop minimum
relative humidity values into the twenties, and even the teens
this afternoon and Tuesday afternoon. The upper level ridge and
thermally induced trough moving east Wednesday but elevated fire
weather concerns could linger. Fuels are approaching critical
levels, but the main concern remains dry grasses or shrubs, or
dead piles of fuels where brush fires may be able to start (as
seen the last few days). Onshore flow will return with improved
low level moisture Wednesday night and Thursday. Weather system
moving into the area will bring a chance of wetting rains for
the first time in a couple of weeks Thursday night and Friday.
Cool weather will continue through the weekend. Felton
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Heat Advisory from 11 AM this morning to 11 PM PDT Tuesday for
Eastern Strait of Juan de Fuca-Foothills and Valleys of
Thurston and Lewis Counties-Foothills and Valleys of the
North Cascades-Foothills of the Western and Southern
Olympic Peninsula-Island County-Lower Chehalis River
Valley-Lowlands of Lewis and Southern Thurston Counties-
Lowlands of Western Skagit and Northwestern Snohomish
Counties-Lowlands of Western Whatcom County-Middle
Chehalis River Valley-Northern Hood Canal-Olympia and
Southern Puget Sound-Port Townsend Area-San Juan County-
Southern Hood Canal-Willapa and Black Hills.
Heat Advisory from 11 AM this morning to 11 PM PDT Wednesday
for City of Seattle-Downtown Everett / Marysville Area-
Eastern Kitsap County-Eastside-Foothills and Valleys of
Central King County-Foothills and Valleys of Pierce and
Southern King Counties-Foothills and Valleys of Snohomish
and Northern King Counties-Lowlands of Pierce and
Southern King Counties-Shoreline / Lynnwood / South
Everett Area.
PZ...None.
&&
$$
NWS SEW Office Area Forecast Discussion