430
FXUS66 KSEW 291040
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
340 AM PDT Sat Jun 29 2024

.SYNOPSIS...Southwesterly flow aloft today with upper level ridge
well to the east and a weakening front moving into the area late
in the day. Front dissipating tonight. Upper level trough moving
through Sunday keeping a chance of showers in the forecast. Upper
level ridge building offshore Monday will drift slowly eastward
moving over the area Thursday and Friday. Warmest day of the year
possible Friday.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...Satellite imagery shows
middle and high level clouds moving across Western Washington
early this morning. Front offshore near 130W. Cloud cover keeping
temperatures on the mild side at 3 am/10z, in the mid 50s to lower
60s.

Middle and high level clouds continuing to stream over the area
this morning. Clouds thickening up this afternoon with the front
close enough for a chance of showers west of Puget Sound in the
afternoon. Air mass somewhat unstable over the Cascades and with
increasing middle level moisture ahead of the front could see a
shower there as well in the afternoon. Highs in the mid 60s along
the coast and upper 60s to mid 70s inland.

What is left of the front moving inland tonight giving most of the
area a chance of showers this evening. With the front lifting to
the northeast the chances for showers will linger over the
northern portion of the area after midnight. Like this morning,
with plenty of cloud cover low temperatures will be mild, in the
mid 50s to lower 60s.

Weak upper level trough behind the front moving through Sunday
keeping at least mostly cloudy skies and a chance of showers in
the forecast. Trough axis moving through midday. Increasing
onshore flow behind the trough axis with a convergence zone
developing over Snohomish county in the afternoon. Little change
in the high temperatures with mid 60s coast and upper 60s to mid
70s inland.

Upper level trough continuing to move east Sunday night. Chance of
showers becoming confined to the Cascades and the convergence zone
over Snohomish county in the evening. Convergence zone will last
into the morning hours Monday. Outside of the Cascades and
convergence zone some clearing Sunday evening but with the low
level onshore flow clouds will fill back in overnight. Lows in the
50s.

Weak trofiness over Western Washington Monday morning with 500 mb
heights rising in the afternoon as an upper level ridge begins to
build offshore. The combination of weak trofiness and a dying
convergence zone will keep a chance of showers in the morning
from about Snoqualmie Pass northward. Morning clouds over the
lowlands giving way to afternoon sunshine with the subsidence from
the upper level ridge building taking care of the morning marine
layer. Highs once again in the mid 60s along the coast and upper
60s to mid 70s inland.

.LONG TERM /TUESDAY THROUGH FRIDAY/...Extended models in good
agreement with what looks like the beginning of the summer pattern
setting up over the Pacific Northwest through the period. Upper
level ridge offshore slowly drifting east ending up over Western
Washington Thursday and Friday. Low level onshore flow Tuesday and
Wednesday weakening Thursday and Friday. Low level flow never
really turns offshore late in the week. 500 mb heights peaking
around 590 dms Thursday into Friday. 850 mb temperatures in the
single digits Tuesday warming to near plus 20C by Friday. With
temperatures aloft this warm even without offshore flow warmest
locations will be pushing 90 degrees Friday. Areas of morning
clouds with afternoon sun Tuesday and Wednesday. Mostly sunny
Thursday and Friday. Highs Tuesday in the mid 60s along the coast
with upper 60s to mid 70s inland. Highs a couple of degrees warmer
Wednesday and Thursday. By Friday, highs in the 70s along the
coast and upper 70s to near 90 inland. Felton

&&

.AVIATION...Southwesterly flow aloft today with upper level ridge
well to the east and a weakening front moving into the area late
in the day. Front dissipating tonight. Upper level trough moving
through Sunday.

Just some middle and high clouds this morning. Ceilings lowering
this afternoon along the coast down to around 5000 feet early
afternoon and to 1000-1500 feet by early evening. For the interior
ceilings lowering to around 5000 feet in the early evening and
down to 1000-2000 feet by midnight. MVFR ceilings continuing into
Sunday morning.

KSEA...Just some middle and high level clouds through 00z this
afternoon. Ceilings lowering to around 5000 feet this evening and
to 1000 to 2000 feet 05z-08z. MVFR ceilings continuing into
Sunday morning. Light northerly winds, less than 6 knots, becoming
south southwesterly 15z-18z. Felton

&&

.MARINE...A weak frontal system will move through the
coastal waters today reaching the inland waters late. The front
will dissipate over the inland waters tonight. High pressure
building offshore Sunday. High pressure over the coastal waters
with lower pressure inland will continue into mid week.

Small craft advisory westerlies possible Sunday evening in the
Central and Eastern Strait of Juan de Fuca with a better chance
for small craft westerlies Monday evening. Felton

&&

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

$$