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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS66 KSEW 251033
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
333 AM PDT Sat Mar 25 2023

.SYNOPSIS...
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A cool and active weather pattern will remain over
Western Washington through the weekend. Lingering cold
temperatures during the overnight and early morning hours may
bring a rain and snow mix both Saturday and Sunday. Drier and
warmer weather is in store early next week.
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&&

.SHORT TERM /TODAY THROUGH MONDAY/...
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The air mass over western WA
remains cool and showery with onshore flow and a deep upper level
low over the region. Temperatures are in the 30s this morning with
a few spots near freezing. Snow levels are low (only around
500-1000 ft) and there`ve been reports of a rain/snow mix in the
lowlands, especially within the convergence zone in King and
Snohomish counties. The convergence zone will be weakening this
morning but until then we will continue to see the threat of a
rain/snow mix. Overall, widespread and significant snowfall
accumulations are not expected. Snow will be tapering down in the
mountains too and the Winter Weather Advisory in the Cascades will
expire at 5 AM as planned. Otherwise, there`s still some moisture
and lift over the area for additional showers this afternoon.
Instability is greatest over southwest WA where there`s a slight
chance of thunderstorms. Temperatures will track cooler than
average with highs in the mid to upper 40s this afternoon.

Western WA is in between systems on Sunday but we`re still under
a broad trough that covers much of the West. There`s still a
little moisture and lift over the area but the overall consensus
in the ensemble guidance is that precipitation amounts will be
light - a few hundredths in the interior and less than 0.10" at
the coast. Cloud breaks will help nudge temps upwards with highs
near 50 although thats` still around 5 degrees cooler than
average.

Model ensemble guidance points toward drier weather as we move
through early next week. This is due to a strong system offshore
that shifts inland to our south on Monday. The low level flow
pattern will be turning offshore for less cloud cover. This will
help temperatures climb closer to normal with highs in the mid
50s. Morning lows will still be cool, though, and in the 30s. 33

.LONG TERM /TUESDAY THROUGH FRIDAY/...An upper low continues to
slowly spin to our south keeping western WA dry as we move through
Tuesday. We then see a ridge nudging inland Wednesday and Thursday
for warmer weather. Highs on Wednesday will be near 60 in the
interior with mid 50s along the coast. The ridge flattens and the
flow turns more zonal toward the latter half of the week with a
return toward wetter weather. 33
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&&

.AVIATION...
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Light flow aloft and low pressure fills and shifts to
the east. Westerly to northwesterly winds from 5 to 10 knots with
gusts to 15 knots at KCLM and KHQM, and southwesterly winds from 5
to 10 knots over the rest of the terminals through this afternoon.
The airmass will turn somewhat unstable with perhaps a few
convective showers and thunderstorms into this afternoon. Another
Puget Sound Convergence Zone may develop late this afternoon into
this evening, lingering showers around KPAE to perhaps KBFI.

Mostly MVFR ceilings through the morning will lift to VFR into the
late morning and afternoon with brief MVFR restrictions in heavier
showers this afternoon.

KSEA...MVFR ceilings through around 18Z will gradually lift to low-
end VFR levels into midday. Brief, sub-VFR restrictions possible
with additional scattered showers and, perhaps, a rumble of thunder
this afternoon as the airmass turns slightly more unstable. Another
convergence zone may develop with showers developing closer to 00Z
then slowly dissipating into the evening. Winds favoring the
southwest from 5 to 10 knots through 00Z then turning south-
southeast into this evening and overnight. Davis
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&&

.MARINE...
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Winds have diminished somewhat overnight, with only
marginal wind gusts from 20 to 25 knots over the coastal waters
today. Northwesterly swell around 14 feet will slowly subside
through the day, dropping below 10 feet by 5 PM. Small Craft
Advisories remain in effect for the coastal, offshore, and West
Entrance region through 5 PM but may be able to come down sooner if
seas drop more quickly.

Mostly quiet conditions are anticipated Sunday through early Sunday
night, though a weak westerly push may necessitate an additional
Small Craft Advisory over the Strait of Juan de Fuca and East
Entrance Region, but hi-res guidance has been marginal enough to
preclude this for now. Otherwise, weak onshore flow will continue
through the day Sunday.

As high pressure moves further inland and a new low pressure system
moves toward the Oregon Coast Monday and Tuesday, offshore flow will
develop with the potential for additional marine headlines. Seas
look to remain below 10 feet into the better portion of next week.
Davis
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&&

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

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
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WA...Winter Weather Advisory until 5 AM PDT early this morning for
     West Slopes North Central Cascades and Passes-West Slopes
     South Central Cascades and Passes.

PZ...Small Craft Advisory until 4 AM PDT Sunday 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-Grays Harbor Bar.

     Small Craft Advisory until 5 PM PDT this afternoon for West
     Entrance U.S. Waters Strait Of Juan De Fuca.
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&&

$$