FXUS66 KSEW 051652
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
852 AM PST Tue Mar 5 2024

.UPDATE...Areas of patchy fog and low stratus will continue to
burn off throughout the morning as skies continue to clear. Drier
air from the northwest will allow conditions to remain mostly dry
throughout the day, except for some light shower activity over the
eastern Olympics and along the shore. Cold air will remain in
place today, causing temperatures to peak roughly 10 degrees below
normal, and near zonal flow tonight into tomorrow will limit much
warming. No updates.

&&

.SYNOPSIS...Lingering moisture from the exiting upper level low may
result in isolated showers at times, otherwise, generally dry
conditions are expected for the remainder of the week. This will be
bolstered by upper level ridging moving into western Washington as
early as Wednesday. This ridge will not bring much in the way of
warming as temperatures will remain below average until the end of
the week. Wet weather returns this weekend.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...Radar generally clear of
echoes this early morning with satellite imagery showing clear or
clearing skies over the western half of the CWA. This clearing is
helping to nudge temperatures downward with most locations reporting
in the lower 30s although a few spots have even gotten down into the
mid to upper 20s.

Dry northwest flow over the region along with the exiting upper
level low will make for generally dry conditions today. There will
be some spots in the Olympics or adjacent that may see a stray
shower or two this afternoon and evening as models are hesitant to
push all the moisture out of the area so soon after the departure of
the low. That said, expectation is for PoPs to remain below 30 pct,
thus falling in the Slight Chance to low-end Chance range. Upper
level ridging pushing into W WA Wednesday will help dry things out
further resulting in a mix of sun and clouds for much of the area
through the majority of Thursday.

Dry conditions and peeks of sunshine do not necessarily make for
warming temperatures though...as both daytime highs and overnight
lows will make readily apparent in the short term. Highs today and
Wednesday will linger in the lower 40s for most lowland locations
before getting a slight nudge upward into the mid to upper 40s
Thursday. That said, normal highs for this time of year fall
squarely in the lower 50s...so will remain below normal for this
time frame. The potential for clear skies at night will not do
overnight lows any favors either, with most locations getting down
to the upper 20s or lower 30s each night, well below the
climatological normal of the mid to upper 30s that would be expected.

18

.LONG TERM /FRIDAY THROUGH MONDAY/...All good things must end and
thus the upper level ridge pushes over the Plains being replaced by
an upper level trough dipping down from the Gulf of Alaska.
Deterministic models tend to actually hold off on bringing the
precip in until early Saturday. However, NBM and ensembles are
leaning toward sneaking the front in almost a full 24 hours
earlier...or slightly more for locations along the coast...bringing
PoPs back into the forecast late Thursday night/early Friday. As the
parent upper level low sits and spins in the Gulf, a series of
fronts will march through W WA for the remainder of the long term
period as if to advertise that once the rain returns, it is not
going anywhere for a bit. QPF values merit watching, especially for
Sunday, as the potential for AR support may trigger hydro concerns.

This period is not only bad news however as temperatures will start
to rise starting Friday and remain near normal for the rest of the
forecast period with most lowland locations seeing daytime highs in
the lower 50s. Overnight lows will get a little shot in the arm as
well since persistent cloud cover at night will keep things warmer.
Current forecast suggests low temps generally in the lower 40s,
which would be just slightly above normal.

18

&&

.AVIATION...A mixed bag of MVFR/IFR ceilings and fog mainly over the
interior lowlands mainly through Central Puget Sound southwards. The
upper level trough will exit the area allowing for light
northwesterly flow aloft and light northerly gradients at low
levels. Conditions are expected to improve to VFR around 17-18z,
with just some high clouds passing by through this afternoon.

KSEA...IFR conditions should improve quickly as shallow fog/stratus
lifts over the next few hours. Ceilings will fill overnight but
remain VFR 4000 to 5000 ft. Light northerly winds around 4 to 8
knots throughout the afternoon.

&&

.MARINE...Generally light and weak benign marine conditions as
flow turns offshore through Wednesday. Weak high pressure will be
replaced by a weak system on Wednesday night. A series of systems
then look to enter into the coastal waters starting Friday, with
southerly winds increasing ahead of a front. The pattern looks
again to turn active heading into the weekend, likely bringing the
return of building seas and advisory strength winds over the
coastal waters.

Mazurkiewicz

&&

.HYDROLOGY...Strong, moist, S/SW flow will bring periods of heavy
rain along the Olympics and Cascades early next week with rising
rivers. Sharp rises are possible on the Skokomish River in Mason
County with flooding possible. 33

&&

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

$$