South Hill, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

039
FXUS66 KSEW 101658
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
858 AM PST Mon Feb 10 2025

.UPDATE...No changes to the overall forecast. Please see the
aviation and marine sections below for updates to those forecasts.


&&

.PREV DISCUSSION... /issued 356 AM PST Mon Feb 10 2025/

.SYNOPSIS...Dry upper level trough moving down from the north
going through the area later today. Narrow high amplitude upper
level ridge just offshore extending north along the British
Columbia coast into Alaska keeping dry cool northerly flow aloft
going into Wednesday. Record low temperatures possible the next
couple of mornings. Pattern breaks down Wednesday night with an
upper level low weakening and moving into Oregon Thursday night
into Friday. Precipitation associated with the low could get as
far north as the Puget Sound area Thursday night into Friday.
Organized front arriving from the west over the weekend moderating
the air mass.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY/...Satellite imagery shows
middle level cloud deck from about Tacoma northward over the
interior. Clear skies elsewhere with patchy freezing fog over the
Southwest Interior. Wide variety of temperatures with the varying
cloud cover at 3 am/11z. Clear areas have dropped into the lower
to mid 20s while locations with cloud cover are mostly in the
lower to mid 30s.

Little weak circulation over the northern portion of the interior
will keep cloud cover over this area this morning. Could see a
brief shower develop out of this feature especially on the
northeast side of the Olympics. Mostly clear skies for the
remainder of the area with the patchy freezing fog dissipating by
late morning. Dry upper level trough moving down from the north
moving through the area this afternoon will clear skies out by
late afternoon. Models are really overdoing the Bellingham to
Williams Lake gradient but there will still be some Fraser River
outflow winds in Whatcom county. High temperatures will continue
to be well below normal, near 40.

Dry and cold northerly flow aloft tonight through Wednesday as a
narrow high amplitude upper level ridge remains in place. This
ridge extends from offshore up the British Columbia coastline then
into Alaska. Clear skies will allow temperatures to drop to near
record levels the next two mornings, mid teens to mid 20s. Even
with plenty of sunshine both days highs will remain near 40. Weak
Fraser River outflow winds will continue over Whatcom county.

.LONG TERM /THURSDAY THROUGH SUNDAY/...Pattern breaks down
Wednesday night as an upper level low develops offshore and begins
moving towards the west coast. Another dry day during the daylight
hours Thursday with the low too far to the west. Lows in the upper
teens to mid 20s. Highs near 40.

Lots of variability in the forecast for Thursday night into
Friday as the low weakens and moves inland over Oregon. The air
mass over Western Washington will be cold enough for the
precipitation to be in the form of snow, 1000-850 mb thickness
values below 1300 meters. The question is how much precipitation
and how far north will the precipitation spinning around the
weakening low get into Western Washington. The operational ECMWF
has the precipitation a little further north versus the GFS.
Ensembles in good agreement with both models having 50-60 percent
of the solutions showing light snow as far north as the Puget
Sound area. A vast major of the ensemble solutions that do
indicate precipitation have very light amounts, under a tenth of
an inch, for Thursday night and Friday. Air mass moderating
slightly Friday afternoon with snow levels rising up to a couple
hundred feet. With nearly half of the ensemble solutions dry will
continue with the chance of snow forecast Thursday night into
Friday with a rain snow mix Friday afternoon.

What is left of the low east of the area Friday night. Models in
good agreement with an organized front moving through the area
from the west during the weekend. This will warm the air mass up
significantly with snow levels rising to over 1000 feet by
Saturday afternoon and up to at least the lower pass levels by
Sunday afternoon. Highs remaining below normal but only by a few
degrees with mid 40s both Saturday and Sunday. Felton

&&

.AVIATION...Northwest flow aloft continues with weak upper
trough axis expected to swing across the area later this afternoon.
The flow aloft becomes northerly tonight. Mostly VFR with areas of
fog and freezing fog producing localized IFR/LIFR conditions into
the late morning. Conditions favored to improve to VFR by 20z with
mainly clear skies tonight. Patchy fog favored to develop once again
overnight for areas mainly south of the Puget Sound. Surface winds
generally N to E 4 to 8 kt, increasing to 5 to 12 kt this afternoon
and decreasing overnight.

KSEA...VFR ceilings with mid-level cloud deck scattering out by
around 00Z then mostly clear thereafter. Surface winds light N/NE
this morning becoming northerly 9 to 12 knots mid-afternoon through
this evening.

27/15

&&

.MARINE...Surface high pressure over the interior of British
Columbia will strengthen today turning the flow northerly and
offshore. Some modest Fraser River outflow is expected to develop
across the Northern Inland Waters. Winds may ease a bit tonight, but
the general pattern will persist into Tuesday. An approaching
surface trough over the Oregon offshore waters will turn the flow
increasingly offshore toward midweek followed by a return of more
active weather by the end of the week.

27

&&

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

&&

.CLIMATE...Here are the record low temperatures for selected
cities around the area Tuesday through Thursday morning. Seattle
Tuesday 23 degrees in 1948, Wednesday 21 degrees in 1949 and
Thursday 18 degrees in 1949. Olympia 18 in 1948, 16 in 1949 and 15
in 1949. Quillayute 22 in 1978, 23 in 1980 and 21 in 1980. Hoquiam
29 in 1959, 27 in 2018 and 25 in 1995. Bellingham 17 in 1981, 10
in 1949 and 7 in 1949. Felton

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Cold Weather Advisory until 10 AM PST Wednesday for East Puget
     Sound Lowlands-San Juan County-Western Skagit County-
     Western Whatcom County.

     Cold Weather Advisory from 6 PM this evening to 10 AM PST
     Wednesday for Bellevue and Vicinity-Bremerton and Vicinity-
     Central Coast-Eastern Strait of Juan de Fuca-Everett and
     Vicinity-Hood Canal Area-Lower Chehalis Valley Area-North
     Coast-Seattle and Vicinity-Southwest Interior-Tacoma Area-
     Western Strait of Juan De Fuca.

PZ...Small Craft Advisory until 6 PM PST this evening for Northern
     Inland Waters Including The San Juan Islands.

&&

$$