Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
048
FXUS66 KSEW 141016
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
316 AM PDT Thu May 14 2026
.SYNOPSIS...
Next system to reach the area will approach the coast this
afternoon then weaken and move inland tonight. Fast moving upper
level trough following the system Friday with another upper
level trough right over Western Washington by Saturday afternoon.
Both Friday and Saturday will be unseasonably cool. Trough
kicks out to the south Saturday night. Upper level ridge
offshore building into Southern British Columbia Sunday. Weak
system trying to move over the top of the ridge Monday. The
ridge rebuilds Tuesday and Wednesday for warmer weather.
&&
.SHORT TERM /TODAY THROUGH SATURDAY/...
If you were wondering if it was unusual to have a 24 degree drop
in high temperatures from day to day in May ( 82 degrees Tuesday,
58 degrees Wednesday ) in Seattle the answer is yes. In 82 years
of records there have only been two times where the day to day
drop in the high temperature in May was greater than 24 degrees.
There were 26 degree drops on May 13th to 14th, 2016 ( 84 to 58
degrees ) and on May 21st to 22nd, 1963 ( 93 to 67 degrees ).
In addition to yesterday there have been two other times with a
24 degree drop in one day, May 11th to 12th, 1971 ( 87 to 63
degrees and May 13th to 14th, 1959 ( 80 to 56 degrees ).
Satellite imagery shows mostly cloudy skies over Western
Washington this morning. Strong upper level winds over the area
with wave clouds over the Cascades into Eastern Washington.
Doppler radar shows the convergence zone hanging tough over
Snohomish county with isolated showers elsewhere. Temperatures
at 3 am/10z were a couple of degrees either side of 50.
Next system to reach the area currently back near 133W will
approach the coast but still be offshore late this afternoon.
Convergence zone dissipating this morning with continuing isolated
showers. Precipitation out ahead of the front spreading over
the area this afternoon. Westerly flow aloft will create a small
rain shadow over the Central Puget Sound. Highs in the mid 50s
to lower 60s.
Front falling apart as it moves inland tonight so will make the
precipitation type showers. Showers coming to an end along the
coast in the evening with decreasing showers over the interior
overnight. A few breaks in the cloud cover will allow
temperatures to drop into the 40s.
Fast moving upper level trough moving into Western Washington
Friday keeping showers in the forecast. Slight chance, 20
percent or less, of afternoon thunderstorms with the trough
becoming negatively tilted as it reaches the area. Very cool day
with highs in the lower to mid 50s. Not record setting low
maximums but close.
Upper level trough moving out of the area Friday night only to
be replaced by an even colder trough Saturday. Snow levels down
to around 3500 feet in the mountains by Saturday. Could see a
couple inches of snow from Stevens Pass northward as well as at
White Pass and Mount Rainier. Air mass somewhat unstable
Saturday afternoon with the trough axis right overhead giving
Western Washington a chance of thunderstorms. Another very cool
day with highs just above record low maximums in the lower to
mid 50s. Felton
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Upper level trough kicks out to the south Saturday night. Upper
level ridge offshore building into Southern British Columbia
Sunday. Weak system coming over the top of the ridge Monday with
slight chance pops North Cascades. Ridge rebuilding Tuesday and
Wednesday.
Warming trend through the period with highs in the lower to mid
60s Sunday and Monday warming to the 60s Tuesday and the 60s to
lower 70s Wednesday.
Chilly morning Sunday with decreasing clouds overnight. Lows in
the mid 30s to mid 40s.
&&
.AVIATION...
Zonal flow aloft through this afternoon as a shortwave ridge moves
through W WA before shifting northwesterly tonight. At the surface,
southerly winds generally 5-10 kts with gusts having generally
eased. This break will be short lived, as gusts are expected to
redevelop later in the morning and remain in place for the majority
of the day. While they should ease tonight, some model data suggests
that they may hang in there beyond 06Z tonight. Even as gusts drop
off overnight, wind speeds are still expected to remain elevated
running 8-12 kts with direction only shifting slightly to south to
southwesterly.
Cigs over the area somewhat mixed. Majority of terminals reporting
VFR, although there is a band running from CLM through to PAE where
a PSCZ has developed. Showers continue to linger there and as such
have given rise to MVFR to IFR conditions. This feature has held on
longer than anticipated and as such the forecast for PAE will likely
need to reflect these current conditions extending into the mid to
late morning time frame come the 12Z update. By noon today,
widespread VFR conditions are expected to return for much of the
day. It is worth noting that as another round of showers starts to
move in this evening, this may bring cigs back down into MVFR,
although models in some disagreement as to how long this might
linger before recovery to VFR conditions once again during the
overnight period. Will continue to evaluate.
KSEA...Some stubborn low clouds at or around 2000 ft causing the
terminal to bounce between MVFR to VFR at least through the early
morning hours...although generally trend in cigs suggest VFR
conditions by mid-morning. As stated above, southerly winds have
lost their gusts for now, but will see them redevelop by 16Z this
morning and remain in place for the remainder of the daylight hours
and into early evening. While the gusts fall off by 06Z, wind speeds
will remain in an 8-12 kt range. Direction to remain southerly to
southwesterly for the TAF period.
18
&&
.MARINE...
Onshore flow will continue, which will allow for daily pushes
through the Strait of Juan De Fuca at least into the weekend. Speeds
expected to largely remain below any headline criteria, although an
occasional gust to 21 or 22 kts is possible. However, this is not
considered to be a widespread threat in either area or time and as
such will hold of on any short term headlines. A more compelling
case for headlines remains on Saturday, where speeds appear to be
more conclusively in Advisory thresholds. A system will pass through
Sunday, allowing for the possibility for increased winds over the
coastal waters.
Coastal seas 4 to 6 feet for much of today before rising to 7 to 9
feet tonight and remaining there into the weekend.
18
&&
.HYDROLOGY...
The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated during
this time as needed.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$
NWS SEW Office Area Forecast Discussion