Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 201531
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
831 AM PDT Sun Jun 20 2021

.SYNOPSIS...Dry weather is expected for the next week. An upper
ridge will bring a warming trend today and Monday with temperatures
peaking on Monday. Onshore flow will bring cooler weather Tuesday
and Wednesday. High pressure aloft will then bring another
warming trend for the end of the week.

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...Sunny and warmer today, the
summer solstice. Expect highs in the 70s to lower 80s. The
current forecast is on track. 33

Previous discussion...An upper ridge will build over the area
today with highs warming several degrees. Weak low level onshore
flow will continue with some low clouds near the coast in the
morning.

The upper ridge will start to weaken on Monday but low level
onshore flow will be weaker or maybe even slight offshore. This
should allow highs to warm several more degrees for the central
and south interior. This will be the warmest day in the near term
with highs near 90 for parts of the central and south interior.

The upper ridge will weaken further Monday night and be replaced
by a weak upper trough on Tuesday. It will remain dry but low
level onshore flow will be stronger. A marine push is likely
Monday night with low clouds spreading at least partially inland
Tuesday morning. Highs will be 5-10 degrees cooler for most of
area on Tuesday. Schneider

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...Low level onshore flow
will bring morning clouds and afternoon sunshine on Wednesday.
Highs will be in the 60s at the coast and 70s inland. This will
likely be the coolest day of upcoming week.

An upper ridge will rebuild over the area Thursday through
Saturday. Low level onshore flow will weaken Thursday and Friday
then turn offshore on Saturday as a thermal trough develops along
the coast. Morning low clouds should become progressively less
extensive Thursday and Friday and pretty much non-existent by
Saturday. Highs will warm around 3-5 degrees each day with
widespread 80s to lower 90s by Saturday. Schneider

&&

.AVIATION...Westerly to northwesterly flow aloft will remain over W
WA into Monday as an upper level ridge remains over the area. VFR
conditions present for the majority of the CWA except for along the
coast, where marine stratus is causing IFR to LIFR conditions.
Expect to see gradual improvement through the morning with clearing
in the afternoon. These clear skies expected to persist for the bulk
of the remaining 24 hour period. The only exception will likely be
HQM, where marine stratus is expected to redevelop tonight. Surface
winds remaining N thru the period under 10kts.

KSEA...VFR conditions for the entire TAF period. Winds N under 10kts.

18

&&

.MARINE...Latest surface analysis this morning shows high pressure
offshore with lower pressure east of the Cascades. This pattern will
allow for enough of a gradient to continue low-end small craft
advisory level winds over the Outer Coastal Waters today, eventually
working their way into portions of the Inner Coastal Waters,
although this looks spotty. Gradients down the Strait also suggest
another round of small craft advisory level winds this evening. As
such, inherited headlines look good for now and will remain in place
for morning update.

Onshore flow strengthens a bit by Tuesday. Small craft winds may
continue over the Outer Coastal Waters, with higher-end small craft
level advisory winds likely (possibly even gales) over the Central &
Eastern Strait Monday and Tuesday evening/night. Will evaluate this
with incoming 12Z data. Thereafter, regular diurnal pushes are
likely down the Strait each evening through the end of the week,
with generally light winds over all other waters.

Kovacik/18

&&

.HYDROLOGY...The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated as needed
until then.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 AM PDT Monday for Coastal Waters
     From Cape Flattery To James Island 10 To 60 Nm-Coastal
     Waters From James Island To Point Grenville 10 To 60 Nm-
     Coastal Waters From Point Grenville To Cape Shoalwater 10
     To 60 Nm.

     Small Craft Advisory until midnight PDT tonight for Coastal
     Waters From Cape Flattery To James Island Out 10 Nm-Coastal
     Waters From James Island To Point Grenville Out 10 Nm-
     Coastal Waters From Point Grenville To Cape Shoalwater Out
     10 Nm.

     Small Craft Advisory from 7 PM this evening to 3 AM PDT Monday
     for Central U.S. Waters Strait Of Juan De Fuca-East
     Entrance U.S. Waters Strait Of Juan De Fuca.

&&

$$

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