Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 172156
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
256 PM PDT Sun Mar 17 2024

.SYNOPSIS...Mostly clear skies continue across western Washington
this afternoon. A few clouds remain off the coast, but will move
as far east as the Olympics Monday morning before receding back to
the Pacific. High temperatures remain well above average through
Tuesday, with a trough bringing chances for showers and cooler
temperatures Wednesday through next weekend.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...An upper level high
remains centered over Washington/Oregon, with ridging as far
north as northern British Columbia/Alberta. This has cleared out
clouds (with the exception of the far outer Washington coastline
with the Pacific Ocean). Temperatures this afternoon have climbed
into the mid 60s, with a couple areas in Eastside Seattle
approaching 70 degrees. Highs will again be near record-levels for
many sites this afternoon, approaching upper 60s and low 70s for
most areas. The coastline will remain cool by about 10 degrees
due to cloud cover (although some areas close to the Olympics
will see higher temperatures with downslope winds from the
Olympics). For Monday/Tuesday, the cloud deck will sneak inland
into the Olympics/west Puget Sound regions from the Pacific,
before receding back to the ocean for the afternoon. This will
knock high temperatures a couple degrees, with the remainder of
the days clearing out of cloud cover.

By Wednesday, the ridge will weaken and give way to a shortwave
trough approaching from the west. This will return the chance of
showers, along with cooler (more seasonal air) that will bring
temperatures down Wednesday. Snow levels will fall to 3,000-3,500
feet, which will make the chance of snow/mixed precipitation
showers possible for the highest elevations. QPF totals remain
light for the lowlands (several hundredths of an inch expected),
but the Cascades/Olympics may see anywhere from a quarter to a
half an inch of QPF.

.LONG TERM /THURSDAY THROUGH SUNDAY/...A series of shortwave
troughs/frontal systems are expected to bring several rounds of
precipitation into the extended forecast. Threat for heavy
precipitation is low at this time. Snow levels will remain around
3,000 feet with the systems passing through. This may lead to snow
showers/mixed precipitation for higher elevations. Most areas will
see highs in the mid 50s, with lows in the low 40s.

HPR

&&

.AVIATION...High pressure with light flow aloft with flow aloft
turning southwesterly Monday. At low levels developing onshore flow
this afternoon will continue through Monday. VFR conditions with
mostly clear skies will linger through this evening before stratus
returns to the coast and inland tonight. There is a good chance of
stratus reaching the South Puget Sound around or after 12z Monday.

KSEA...Mostly clear skies. Westerly winds 4 to 6 knots will continue
to veer to the northwest and and northerly through the early
evening.

&&

.MARINE...Developing onshore flow this afternoon will remain
onshore into the middle of week. Stronger onshore gradients
Tuesday night into Wednesday look to be the most likely period for
small craft advisory winds in the central strait. A weak surface
low will move into the coastal waters Wednesday night and
Thursday.

&&

.HYDROLOGY...No flooding is anticipated in the next seven days.

&&

.CLIMATE...Some fun with numbers. What does a 70 degree plus day
in March in Seattle mean for April weather? In the previous 14
years with at least one 70 degree plus day in March the following
April has had above normal temperatures 11 times, below normal 2
times and one year was near normal. In the last 8 occurrences the
following April have all been above normal with every year
ranking in the top 20 warmest Aprils including 4 of the top 10
warmest and the warmest April on record ( 56.7 degrees in 2016 ).
Felton

&&

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

$$


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