Tacoma, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

928
FXUS66 KSEW 180412
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
812 PM PST Fri Jan 17 2025

.UPDATE...Generally clear skies this evening with localized fog
development mainly from Olympia southwards. Fog may develop
further tonight into Saturday morning, especially around the
Southwest Interior and into south Puget Sound. Otherwise, a Cold
Weather Advisory remains in effect for western Whatcom County into
Saturday morning, with colder temperatures across Western
Washington as well. No further updates this evening. JD

&&

.SYNOPSIS...High pressure will dominate the weather into the
middle of next week, bringing dry conditions and colder
temperatures. Overnight lows are expected to fall below freezing
over much of Western Washington this weekend and into next week.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...An upper-ridge continues
off the coast as it axis punches well into Alaska. At the surface,
a 1037 mb surface high is sitting just west of Haida Gwaii but its
influence can be felt across the region. Here locally, higher
pressure along with northerly flow aloft are maintaining dry and
chilly weather. For tonight, this trend will persist as temps cool
down with widespread 20s expected into Saturday morning.
Anomalously cool overnight lows in concert with 20-25 mph wind
gusts are enough to allow the issuance of a Cold Weather Advisory
for the lowlands of W Whatcom County tonight into Saturday
morning. Apparent temperatures are forecast to get as low as 20 F
for this area during this time. HREF guidance has a 70% chance of
apparent temps getting below 21 F, further increasing confidence. Cold
weather may cause impacts to vulnerable populations,
infrastructure, etc.

The pattern will remain locked through this weekend as the upper-
ridge sits offshore. Guidance has it progressing gently on Monday
as its axis becomes more in line across the PNW. Dry and calm
conditions are to remain throughout the short-term forecast
(barring a stray shower or two). The weather may be calm, but also
cold as below- normal temperatures continue. Overnight lows will
feature widespread 20s throughout this period with daytime highs
in the lower 40s. Can`t rule out spells of patchy fog during the
nighttime and morning hours.

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...Lower heights are forecast
to rebound aloft on Tuesday as a transient shortwave pushes
through. With it, a weak front may drag across the region as
the NBM has slight PoPs returning by midweek. Ridging looks to
rebound by Wednesday-Thursday but much uncertainty exists on the
evolution of the upper-level pattern going into Friday.
Regardless, the NBM has latched on to this uncertainty and has
introduced PoPs, albeit weak ones, starting Wednesday and carrying
through the second half of the new week. Below normal temperatures
are favored for much of the long term.

McMillian

&&

.AVIATION...An upper level ridge built inland over western
Washington today. Northwest flow aloft will continue. Most mid level
clouds dissipated this evening (with some areas seeing nearly clear
skies). This has opened the door for redevelopment of LIFR
fog/stratus, and has since begun in the Olympia area this evening.
Coverage is expected to increase into southern Puget Sound overnight
tonight (potentially up to South Seattle). Additional terminals that
have calm winds will have an increased risk of fog/mist in the
morning (with the north gradients and cooler temperatures tonight
close to the dew points). Clearing to VFR will take place late
Saturday morning and afternoon. Winds will be calm overnight into
Saturday morning, becoming light out of the north at 4 to 8 kt
(couple gusts in the KBLI vicinity are possible from Fraser River
outflow).

KSEA...VFR with a light north wind early this evening. Risk of
either low stratus or fog has increased, and based on observations
to the southwest, the best chance will be from 09Z-18Z. Winds are
expected to remain light out of the north overnight, but will pick
up at 4 to 6 kt in the morning, and increase to 4 to 8 kt in the
afternoon. Ceilings/fog will scatter late Saturday morning or
afternoon.

Cullen/HPR

&&

.MARINE...High pressure continues to build offshore and push
over the region into the weekend. Offshore winds increase a bit at
times this weekend, with gusty winds to 20 kt possible over portions
of the northern interior waters with outflow from the Fraser.
Another round possible Sunday late. A weak system will likely fade
offshore as it approaches the coastal waters around Tuesday, with a
return of high pressure and related offshore flow around midweek.
The next stronger frontal system could approach late next week. Seas
will remain below 10 feet through the forecast period, though seas
will remain mixed with a notable long period wave group and a
shorter period group both passing through the coastal waters through
the weekend.      Cullen

&&

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

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Cold Weather Advisory until 10 AM PST Saturday for Western
     Whatcom County.

PZ...None.
&&

$$