866
FXUS66 KSEW 121650
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
950 AM PDT Sun Apr 12 2026
.UPDATE...
Satellite imagery shows low cloud deck hanging tough over
portions of the area this morning. Stratus isn`t very deep with
tops below 2000 feet. Low level flow is light which will make it
hard to get rid of the cloud cover. In addition to the light
flow in the lower levels high clouds moving through this
morning will also hinder the breaking up of the low cloud deck. Current
forecasts have a late afternoon break out and that looks good at
this point. With the cloud cover hanging on highs a touch warm
in the forecast with mid to upper 50s instead of lower 60s.
Previous discussion follows with updated aviation section. Felton
&&
.SYNOPSIS...
Onshore flow will increase tonight and Monday for
showers and a convergence zone. The next system will bring
additional lowland rain, windy conditions plus possible heavy
mountain snow on Tuesday. Upper level low over western
Washington Wednesday for continued cool conditions. Drying
northerly flow aloft developing Thursday into the weekend.
&&
.SHORT TERM /TODAY THROUGH TUESDAY/...
A brief break in the weather this morning and early afternoon
as an upper level low shifts inland to our south (over northern
CA). Showers will then increase late this afternoon and evening,
primarily over the interior and Cascades, as low level onshore
flow increases. Onshore flow continues into Monday with
convergence zone showers over King/Snohomish counties.
Cool, wet and windy conditions are ahead as we move into Tuesday
while a deep upper low descends south from B.C. Snow levels will
lower to around 3000 ft with snow expected at all Cascade
passes. Winds will be gusty from the S/SW with gusts to 25-35
mph (peaking in the interior during the afternoon). 33
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Wet and cool conditions will continue Tuesday night and
Wednesday as a deep upper low spins over WA. Snow levels will
lower further, down to around 1500-2000 ft, with snow in the
Cascades and passes. Mean 48 hour snow totals range from 6 to
12" inches with higher amounts on the volcanoes. Expect cooler
lowland temperatures with lows in the 30s and highs in the 40s
to around 50.
Drier weather is in store Thursday into the weekend with high
pressure. Lows remain chilly and in the 30s with freezing
temperatures around the south sound. Expect highs in the 50s
with lower 60s by Saturday. 33
&&
.AVIATION...
Variable to northerly winds aloft as a weak trough sets up over
western Washington. Fog and low clouds have brought IFR to LIFR
cigs/vis but conditions are beginning to gradually improve. VFR
is slated to return by 20-22z. Winds will remain northerly
throughout the afternoon but will keep speeds generally 3 to 6
knots. MVFR/IFR cigs are like to redevelop this evening for
Puget Sound terminals as a convergence zone develops.
KSEA...LIFR conditions have lifted to IFR so far this morning as fog
and low clouds developed earlier at the terminal. Northerly winds
generally around 3 to 6 knots and remaining there throughout the
afternoon. Latest guidance shows a 60-70% chance of conditions
returning to VFR by 18z-20z as fog/low clouds start to dissipate.
Winds will start to turn more SW by 20z and increase slightly to 4
to 8 knots. MVFR/IFR cigs are to return this evening as a
convergence zone develops.
Mazurkiewicz/McMillian
&&
.MARINE...
Surface low pressure continuing to move southward as a high
pressure system develops offshore in the northeastern Pacific.
Generally calm and benign northerly winds over the waters this
afternoon. A small craft advisory remains in effect for
increased westerlies down the Strait of Juan de Fuca late Sunday
into Monday. A stronger frontal system arriving late Tuesday
into Wednesday will likely yield additional headlines as we will
see increased winds and seas.
Coastal seas 4 to 6 feet throughout the weekend. Seas will then
start to build upwards to 8 to 10 feet by Tuesday evening and
remaining elevated through Thursday.
Mazurkiewicz
&&
.HYDROLOGY...
No river flooding the next 7 days.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 5 PM this afternoon to 11 AM PDT
Monday for Central U.S. Waters Strait Of Juan De Fuca-
East Entrance U.S. Waters Strait Of Juan De Fuca.
&&
$$
NWS SEW Office Area Forecast Discussion
Discussion Script by Ken True at Saratoga Weather - WFO Script by SE Lincoln Weather
