112
FXUS66 KSEW 200356
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
756 PM PST Sun Jan 19 2025

.SYNOPSIS...High pressure will dominate the weather into the
middle of this week, bringing dry conditions and cold overnight
temperatures. Lows will fall below freezing over much of Western
Washington tonight and into next week while daytime highs will
remain below normal.

&&

.UPDATE...Quiet evening weather-wise. Temperatures this evening
are already in the low 30s across the majority of western
Washington, and will continue to drop through tonight (especially
with clear skies and light east Cascade gap winds). Cold weather
advisories will remain in effect through tonight, and additional
details of the forecast are available below.

HPR

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...Mostly clear skies
across W WA as lingering fog/low clouds have eroded. Upper-
ridging is in place offshore leaving W WA under dry northerly flow
aloft. This feature will continue to be the main influence
throughout the short-term period along with below average
temperatures. For tonight, dry and cold weather is favored with
widespread 20s in the forecast. A Cold Weather Advisory remains in
effect tonight through Monday morning for the Seattle, Tacoma,
Bellevue, Everett, Bremerton and vicinities. An additional
advisory has been issued for East Puget Sound Lowlands for the
same time. Confidence has increased on east winds producing wind
chill values as low as 15 to 20 F, especially for areas along the
Cascade gaps such as North Bend. Monday`s weather is likely a
carbon copy of Sunday`s as we`ll wake up to cold, frosty
conditions with areas of fog. We`ll warm up into the lower 40s
across the CWA as mostly sunny skies prevail but still well-below
average for daytime highs for mid- January. The aforementioned
ridge axis will cross the PNW by Monday afternoon as a shortwave
trough and weak front is hot on its heels. Increasing cloud
coverage may bump temperatures up by a few degrees for Monday
night but cold conditions are likely to remain.

Models aren`t too impressed with the shortwave trough as precip
chances remain next to none for Tuesday. Dry weather and below
average temperatures will remain in store through midweek as
guidance is in firm agreement with the redevelopment of ridging
over the region on Wednesday. Daytime highs will continue in the
lower to mid 40s with overnight lows in the mid 20s to lower 30s.

.LONG TERM /THURSDAY THROUGH SUNDAY/...Ridging remains into
the first half of Thursday but trough influence may return by
Thursday evening, although there`s disagreement on exact timing
and intensity. Regardless, the NBM has latched on to this
and has introduced PoPs, albeit weak ones, on Thursday and
carrying into Friday. Below normal temperatures are favored for
much of the long term. Ridging appears more favorable into the
weekend.

&&

.AVIATION...An upper ridge will remain offshore through tonight for
continued northerly flow aloft, before transitioning to more
westerly flow Monday afternoon. VFR through this evening with mainly
SKC. Areas of FZFG will develop again tonight into Monday morning,
particularly from OLM southwards and in local river valleys, with
LIFR conditions in these areas. VFR conditions elsewhere. High
clouds will then increase later Monday into Monday night. North to
northeast winds continue into this evening, remaining locally breezy
near BLI with gusts up to 15 to 20 kts. Winds will then become
lighter overnight into Monday with more of an easterly component.

KSEA...VFR conditions with SKC into tonight. Generally VFR
conditions expected to continue into Monday. There remains a slight
chance of localized FZFG developing in the vicinity of SEA early
Monday morning, primarily between 13 to 17z. However, confidence
remains low. High clouds will increase Monday afternoon. N winds of
8 to 14 kts will continue into this evening before becoming more ENE
tonight into Monday morning at 4 to 8 kts. JD

&&

.MARINE...High pressure will remain over the waters through Monday.
Offshore winds will continue through Monday as well. Fraser River
Outflow may bring occasional wind gusts of 20 to 25 kt to
portions of the northern Inland Waters, particularly this evening.
Locally breezy east winds will also exist through tonight for
central and western Strait of Juan de Fuca and northern Coastal
Waters. However, widespread SCA wind gusts are not expected during
this period.

A frontal system will weaken as it crosses the region Monday night
into Tuesday, bringing no significant impact to the waters. High
pressure will then rebuild later Tuesday through midweek for another
round of offshore flow. Another weather system will slide southward
across the waters later Thursday into Friday for increasing north
winds, especially for the Coastal Waters. SCA winds may be possible
for the Coastal Waters due to winds during this period.

Seas will range 6 to 8 feet through Tuesday night before subsiding
to 3 to 5 feet on Wednesday. Seas will then build again to 8 to 12
feet later Thursday into Friday. 33/JD

&&

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

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Cold Weather Advisory from midnight tonight to 8 AM PST Monday
     for Bellevue and Vicinity-Bremerton and Vicinity-East Puget
     Sound Lowlands-Everett and Vicinity-Seattle and Vicinity-
     Tacoma Area.

PZ...None.

&&

$$