Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
000
FXUS66 KSEW 272225
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
325 PM PDT Wed Mar 27 2024

.SYNOPSIS...An upper level low will maintain showers over the
region through Friday. High pressure will build across the
Pacific Northwest this weekend into Monday, bringing warmer and
drier conditions. A return to a cooler and wetter pattern looks to
occur by the middle of next week.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...We`re in post-frontal
flow this afternoon with showers becoming more scattered across
western WA. The air mass is still cool and and slightly unstable
for a chance of thunderstorms this afternoon and early evening,
especially along the coast and Southwest Interior. Expect
overnight lows in the lower 40s with a few upper 30s possible.

A stacked low will continue to spin offshore on Thursday with
moist/diffluent flow over western WA. This leads to additional
showers across western WA with another thunderstorm threat along
the coast. Heavier showers and possible thunderstorms are possible
over the North Cascades as well. Snow levels will hover around
3500-4000 ft with a few inches of snow over the higher peaks and
passes.

The offshore low starts to drift south on Friday while cutting
off the moisture tap to our region. So overall a down tick in
shower activity for western WA. Temperatures will be a little
warmer and closer to average with highs in the mid to upper 50s.

Saturday is looking drier as the flow aloft becomes more
northerly. We should see more sunshine with highs in the interior
reaching the lower 60s. 33

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...Dry and mild weather
continues into early next week as high pressure moves in. Highs
will track a few degrees warmer than average and in the lower to
mid 60s. The coast will be cooler and in the 50s with NW winds.
Rain chances increase Tuesday and/or Wednesday as the next
Pacific Frontal system tracks down from B.C. The snow levels will
be lower by Wednesday with a few inches of snow in the Cascade
passes. 33

&&

.AVIATION...Southwest flow aloft as troughing resides offshore.
Mostly VFR this afternoon aside from localized MVFR-IFR under shower
activity. Low-end VFR to high end MVFR is likely to persist tonight
along with shower activity. Locally lower ceilings and visibility
will be impacted in the heaviest showers. South-southwest winds this
afternoon will gradually turn out of the southeast late overnight
between 6-12 kt for most terminals. Terminals such as KBLI and KHQM
could see isolated gusts upwards of 20 kt.

KSEA...VFR should remain through much of the upcoming TAF period.
Can`t rule out isolated instances of MVFR under heavier shower
activity this afternoon into tonight. A slight chance of thunder
also exists in the afternoon/early evening, but confidence is too
low to include in the TAF. SW winds 8-12 kt this afternoon before
eventually turning SE after 06z.

McMillian

&&

.MARINE...A sub 985mb surface low continues to churn offshore. Its
associated fronts have made their way inland but headlines still
remain. Small Craft Advisories continue through Thursday for parts
of the strait, as well as Admiralty Inlet, coastal waters, and the
Northern Inland Waters. An unstable airmass behind the front will
promote scattered thunderstorm development into this evening.
Lightning, small graupel/hail, and gusty outflow winds may be
possible with the strongest cells. As the aforementioned surface low
tracks off and away by Friday, any remaining headlines should be
allowed to expire as high pressure returns. Here we`ll see benign
conditions for the weekend and into the beginning of next week.

Seas 6 to 8 ft this evening before rising late tonight into Thursday
to 13 to 16 ft. Seas will then relax below 10 ft Friday to around 5
to 7 ft for the weekend and early next week.

McMillian

&&

.HYDROLOGY...No river flooding over the next 7 days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 11 PM this evening to 5 PM PDT
     Thursday for Admiralty Inlet-East Entrance U.S. Waters
     Strait Of Juan De Fuca-Grays Harbor Bar-Northern Inland
     Waters Including The San Juan Islands-West Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Gale Warning until 2 PM PDT this afternoon for East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 2 PM PDT this afternoon for Admiralty
     Inlet-Northern Inland Waters Including The San Juan Islands.

     Small Craft Advisory from 5 PM this afternoon to 5 PM PDT
     Thursday for Coastal Waters From Cape Flattery To James
     Island 10 To 60 Nm-Coastal Waters From Cape Flattery To
     James Island Out 10 Nm-Coastal Waters From James Island To
     Point Grenville 10 To 60 Nm-Coastal Waters From James
     Island To Point Grenville Out 10 Nm-Coastal Waters From
     Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal
     Waters From Point Grenville To Cape Shoalwater Out 10 Nm.

&&

$$


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.