Seattle, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

439
FXUS66 KSEW 031105
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
305 AM PST Tue Dec 3 2024

.SYNOPSIS...High pressure aloft will allow for continued dry
conditions with morning fog and low stratus. The upper ridge will
break down towards the end of the week as the next storm system
approaches, bringing in the next chance for widespread
precipitation across the region late this week and through the
weekend.

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.SHORT TERM /TODAY THROUGH THURSDAY/...High pressure aloft will
remain firmly in place through Wednesday, maintaining dry and
stable conditions with rounds of morning fog and low stratus.
Upper level clouds along the periphery of the ridge are limiting
the extent of dense fog early this morning, though surface
observations show pockets of greatly reduced visibility. Cold
overnight lows will also give way to the development of freezing
fog in areas that fall below freezing this morning, primarily
south of the Puget Sound. The forecast will continue to see little
change day to day, with highs in the upper 40s to lower 50s and
lows near freezing across the lowlands.

A pattern change is on track for Thursday and beyond, with more
active weather settling back into the region. An upper level
trough will override the high pressure ridge on Thursday, bringing
in a quick shot of rainfall to western Washington. This system
will increase mixing that will help to erode the ridge and scour
out the lower level air mass that has brought fog each morning.

.LONG TERM /FRIDAY THROUGH MONDAY/...A warm front will lift across
the region on Friday, bringing in widespread rainfall with snow
levels near 7000-9000 ft. Temperatures Friday will peak well into
the 50s across the lowlands. A cold front will follow closely
behind on Saturday as an upper level trough settles over the
region, bringing in more precipitation and lowering snow levels to
3000-3500 ft by Saturday night. Forecast models shift a cutoff
low inland on Sunday, with a majority of continued shower activity
occurring over the northern Cascades. A ridge is on track to
develop inland towards the beginning of next week, drying things
out as northerly flow aloft keeps cooler temperatures in place.

15

&&

.AVIATION...Upper level ridging over the region will keep flow
aloft in the midlevels light and zonal. Surface winds are primarily
light and variable for the interior terminals and lightly offshore
for terminals along the south interior, coast, and Strait of Juan
de Fuca.

Conditions are largely IFR to LIFR early this morning with another
round of widespread fog redeveloping across western Washington.
Conditions will likely remain IFR to LIFR through the morning
hours, though guidance does continue to indicate a return to more
widespread MVFR to VFR conditions by mid afternoon/early evening.
Confidence in this improvement trend remains low given the trends
over the past few days and the stagnant weather pattern. Some
spots may see fog linger in places throughout the day. Light
offshore flow may help to dry out the lower levels somewhat, but
guidance shows another round of fog redeveloping across the
interior Tuesday night into Wednesday.

KSEA...Conditions LIFR in fog. Fog looks to linger through the
morning hours, with guidance hinting at improvement towards
MVFR/VFR by the mid to late afternoon hours. Given trends over the
past few days, however, confidence in improvement remains low.
Winds will remain light at 6 kts or less and primarily out of the
N/NE through the TAF period.

14

&&

.MARINE...High pressure will remain situated across the area
waters through midweek, keeping winds generally light and offshore
through Wednesday. Widespread fog redeveloping nightly could limit
visibilities to less than 1NM over portions of the waters today
and again on Wednesday. Seas will primarily hover between 5-8 ft
through midweek. The next frontal system will approach the coastal
waters on Thursday with another, stronger system slated to move
into the waters Friday into the weekend. The system on Friday will
bring stronger southerly winds to the coastal and north interior
waters and will allow for seas across the coastal waters to build
to 10-15 ft.

14

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.HYDROLOGY...An upper ridge will remain in place across Western
Washington through Wednesday. A frontal system will move through
on Thursday for lighter QPF amounts. Another weather system Friday
into Saturday is forecast to bring heavier QPF amounts. In
addition, snow levels are expected to rise later Friday into early
Saturday to 7000 to 9000 feet. This, combined with rainfall, will
result in rises on rivers across Western Washington. At this
time, the Skokomish River is the main river of concern for
potential river flooding during this period. However, other area
rivers will need to be monitored due to the higher snow levels
Friday into Saturday.

JD

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

$$