National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS66 KSEW 180319
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
819 PM PDT Wed Apr 17 2024

.SYNOPSIS...Dry spring time weather with cool overnight
temperatures and warmer than normal high temperatures will linger
through the end of the work week. A weakening front will bring
increased clouds, cooler temperature, and widespread precipitation
Saturday afternoon and evening followed by lingering showers Sunday.
Warmer and dry weather will kick the new week off Monday.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...Satellite imagery
showing clear skies across western Washington, with temperatures
in the low to mid 50s. Additionally, dew points are very low--in
the mid to low 20s across the interior, up to 30 along the Pacific
coast. With these conditions, as well as winds easing up
overnight, temperatures should be able to rapidly fall with
efficient radiative cooling. Low temperatures should bottom out in
the low 30s to upper 20s, but could reach down into the mid 20s
in areas best sheltered from wind. A Frost Advisory in effect for
most of Grays Harbor, Thurston, and Lewis counties, as well as the
East Puget Sound Lowlands zone. Stronger northeasterly wind over
western Whatcom and Skagit counties may limit how fast
temperatures can drop.

An upper level trough moving down the backside of the offshore
ridge late tonight and is expected to linger in the area into
Thursday night. This continues to be a dry feature with perhaps a
few more mid and high clouds and another sunny day. Thursday highs
will be a little warmer - pretty solidly in the 60s.

Friday looks to be the warmest day as the upper level trough
kicks east, and the offshore upper level ridge building.
Importantly low level flow becomes more easterly with gusty
easterly winds in the Cascade Foothills. High temperatures will
tip a bit higher into the upper 60s and lower 70s.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...The distribution in the
ensembles continue to highlight the offshore ridge moving through
Western Washington Friday night followed by a negatively tilted
front Saturday. This will bring widespread rain and some gusty
winds then lingering showers Sunday. There looks to be a good
chance an high pressure to some degree Monday with drier and
warmer weather to open the new week. There are enough members that
keep some potential for precip Tuesday, but there are higher odds
for generally dry weather lingering into mid week - typical Spring
weather either way.

Cook/LH

&&

.AVIATION...Northwesterly flow as an upper level ridge builds to our
west with thermal troughing strengthening into Thursday along the
coast. A combination of the two will lower sub-VFR stratus
potential, though cannot rule out isolated areas of patchy fog or
frost early Thursday morning (due to weak north flow aloft). Winds
at the surface will remain northerly through the TAF period, with
flow turning easterly along the coast as the ridge moves over
Thursday. Wind gusts from 14 to 20 kt possible 20-03Z Thursday
afternoon.

KSEA...VFR  and clear skies with northwesterly flow aloft and light
northerly flow at the surface. Winds will remain northerly through
the TAF period, with gusty winds up to 15 to 20 kt Thursday
afternoon.

Davis/HPR

&&

.MARINE...An upper level ridge will continue to build offshore over
the Pacific, and will move inland on Thursday. High pressure further
inland combined with a surface trough along the coast will promote
offshore flow with gusty east winds of 10 to 20 kt through the
Strait of Juan de Fuca, into the northern offshore waters, and
through the central Puget Sound. Probabilities for wind gusts
exceeding 20 kt around 40-50%, thus, will continue to monitor need
for Small Craft Advisories for these localized areas. The next
frontal system is expected to cross the area waters Saturday with
the next chances for widespread marine headlines.

Expect seas to remain around 3 to 6 ft through Saturday, then rising
to 8 to 10 feet into Sunday.

Davis/HPR

&&

.HYDROLOGY...No river flooding expected for the next 7 days.


&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Frost Advisory from 2 AM to 8 AM PDT Thursday for Central Coast-
     East Puget Sound Lowlands-Lower Chehalis Valley Area-
     Southwest Interior.

PZ...None.
&&

$$