South Hill, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

246
FXUS66 KSEW 211813
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
1013 AM PST Thu Nov 21 2024

.SYNOPSIS...An upper-low looks to churn off the PNW coast through
the start of next week with active weather. A shortwave trough
will enter today with increased shower chances followed by a
strengthening surface low (not as intense as Tuesday`s) drawing
near on Friday. Here we`ll more widespread precipitation and gusty
winds.

&&

.UPDATE...No immediate update to the forecast below this morning.
Showers are continuing along the coast this morning, but the
threat of thunder is significantly lower than yesterday. High
resolution guidance shows possible showers from the
Olympics/Kitsap Peninsula up through Puget Sound later this
afternoon and evening. Otherwise much quieter this afternoon. The
next low pressure system will arrive Friday with a couple rounds
of wind, and more widespread precipitation (see discussion below
for details).

HPR

&&

.SHORT TERM /TODAY THROUGH SATURDAY/...Good morning, western
Washington. Current temperatures as of 1115z UTC: Boeing Field 43
F, Chehalis-Centralia Airport 48 F, Seattle Paine Field 46 F.

A beast of a surface low that`s responsible for greatly
inconveniencing western WA on Tuesday evening continues to swirl
and fill over the NE PAC. Its center is roughly 200 NM west of the
Vancouver Island coast and 350 NM WNW of Cape Flattery. Although
far away, we`ll continue to feel its influence today. Scattered
showers and temperatures in the upper 30s to mid 40s will start
things off. As the day progress, showers are on tap to persist
into the afternoon as a shortwave ejects out of the
aforementioned low center`s mid-level circulation. Snow levels are
to range between 3,000 to 4,000 ft as wintry precipitation is
slated for the higher passes. Rainfall will top out around
0.10-0.25" with snowfall less than an inch or two for mountain
passes such as Stevens. Showers are to end during the early
evening however, widespread rainfall will soon replace it.
Overnight lows are to fall into the 40s.

As alluded to, widespread rainfall will arrive during the early
morning hours on Friday. A deepening surface low will parallel the
coast similarly to its predecessor just a few days ago. By 12z
Friday, global deterministic guidance has this disturbance around
980 mb as its tightening pressure gradient increase wind speeds.
HREF probabilities has 70-80% chance of wind speeds greater than
30 mph on Friday along the immediate coastline as a Wind Advisory
has been issued. Probabilities are slightly less, but a Wind
Advisory has also been issued for the Cascade foothill due to
easterly gap winds Thursday night into early Friday morning.
Winds aren`t expected to be as strong as Tuesday evening`s but,
conditions could make clean up efforts more complicated for
already wind-beaten areas. A warm front will punch snowlevels
upwards above 6,000 ft so snow should transition over to rain
briefly but a trailing cold front will crash snowlevels back down
to 3,500 ft for the mountains by Tuesday evening. Showers will
linger into Saturday as the upper-low persists offshore. High
temperatures will warm to the lower to mid 50s on Friday before
falling to the upper 40s to near 50 F on Saturday.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...Models are hinting at the
upper level low to move inland by Tuesday. There is some
uncertainty on where exactly the low will track towards. With the
low expected to depart, it appears the wet weather will be
replaced with drier weather come midweek as ridging builds back
into the region.

McMillian

&&

.AVIATION...Expect predominantly VFR ceilings and light wind
across the region with southerly flow aloft as a deep low remains
offshore over the eastern Pacific. The closer movement of this
deepening low will bring gusty east winds through the Cascades after
around 09z through 15z, strongest nearer the Cascades but still
gusting to 30 kt for favored locations downwind of the gaps. This
could pose a crosswind threat for terminals with only north/south
aligned runways. A warm front will bring some lower ceilings
(approaching or into MVFR range) along with some rain, followed by a
shift to southerly winds. These southerly winds will again be gusty,
strongest near the coast and the I-5 corridor/Puget Sound terminals.
Showers continue in the post-frontal air mass with a low (10-15%)
chance of a few isolated thunderstorms west of the Sound (highest
closer to the coast). Southerly winds eventually subside late
Friday.

KSEA...Wind will become easterly today and increase tonight by 09z,
with the potential for east gusts continuing through 15z.
Southerly winds, also gusty, will follow during the day on Friday.
Otherwise, VFR conditions through the day, with increased
likelihood of MVFR ceilings with the warm front overnight along
with the east wind gusts.

&&

.MARINE...A brief lull in the weather today before another deep
surface low spins offshore to 30 kts on Friday. This system again
has potential for storm force winds over the coastal waters and
may generate large S/SW swells over 20 ft. Easterly gales are also
possible through the Strait of Juan de Fuca and a Gale Watch is
in effect. Winds will ease and seas will subside over the weekend
as the low weakens over the offshore waters. 33

&&

.HYDROLOGY...The Skokomish river will stay between action
and minor flood stage through Saturday. As rain falls and with some
snowmelt contribution beginning on Friday morning, the river may
briefly rise into minor flood stage by late Friday into early
Saturday morning.

For the remainder of the rivers no flooding is expected. Lower snow
levels in the Cascades will limit runoff and reduce any flooding
chances for rivers flowing off the Cascades. Precipitation for the
remainder of the period will come in bursts. This combined with snow
levels remaining relatively low will keep rivers in their banks.
Felton/Kristell

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Flood Watch through late Friday night for Hood Canal Area-Lower
     Chehalis Valley Area-Olympics.

     Wind Advisory from 10 AM Friday to 4 AM PST Saturday for Central
     Coast-North Coast.

     Wind Advisory from 10 PM this evening to 10 AM PST Friday for
     Bellevue and Vicinity-East Puget Sound Lowlands.

PZ...Small Craft Advisory until 4 PM PST this afternoon for Grays
     Harbor Bar.

     Gale Warning from 10 PM this evening to 4 AM PST Saturday for
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca-West Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Storm Warning until 4 AM PST Saturday 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.

&&

$$