Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
FXUS66 KSEW 280358
Area Forecast Discussion
National Weather Service Seattle WA
858 PM PDT MON JUN 27 2016
SYNOPSIS...No significant weather systems will affect the region
tonight through Thursday. Cloudier, cooler weather with a chance
of showers will arrive for the weekend.
SHORT TERM...A weak upper level short wave trough cut through the
region today, triggering a few showers and thunderstorms near and
east of the Cascade crest. These showers are fading away this
evening. It is dry elsewhere across Western Washington with
stratus clouds along the coast. The stratus clouds will push
farther inland Tuesday morning and into the central portion of
Puget Sound, then burn back to the coast in the afternoon.
Otherwise, Tuesday will be another dry and warm day with highs in
the interior near 80. The coast will remain cloudy, cool and in
the 50s to lower 60s. There is a weak upper level trough over the
Pac NW Wednesday and Thursday although 500 mb heights are still
high in the 580s. Onshore flow is a little stronger so we`ll
likely see an increase in morning low clouds/stratus. Temperatures
will remain a few degrees above normal in the interior. 33
LONG TERM...Previous discussion...Upper heights will fall off and
the weather pattern will change to one of a deep marine layer and
a possibly enough lift for some showers as weak troughs reach the
area. Overall, a large upper trough will gradually develop over
the region and by Sunday or Monday additional shotwaves rotating
through the longwave trough could give some precip. The 12z GFS
has the best looking little closed upper low dropping over the
area Sunday afternoon and evening. The ECMWF seems also to have
that idea but holds it off til Monday. There is a good chance of
the Puget Sound Convergence Zone setting up at least a couple of
times over the holiday weekend.
AVIATION...A upper level ridge will remain centered over Idaho
with southwest flow aloft over Washington. At the surface, onshore
flow will continue tonight and Tuesday. The air mass is dry and
stable except for marine stratus along the coast. Areas of stratus
will spread inland tonight to around Puget Sound, then evaporate
back to the coast Tuesday afternoon.
KSEA...Clear skies this evening with westerly wind 5-10 knots. There
is a good chance stratus will reach the terminal after sunrise
Tuesday morning. The wind should become light southerly early
MARINE...Onshore flow will prevail through Friday with high
pressure offshore and lower pressure inland. At least small craft
advisory strength west winds will occur each day in the central and
eastern Strait. Gale force westerlies will occur tonight and may
occur again Tuesday night. Small craft advisory strength winds are
possible on the coast at times as well. CHB
PZ...Small Craft Advisory until 11 AM PDT Tuesday 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 James Island To Point Grenville Out 10 Nm-
Coastal Waters From Point Grenville To Cape Shoalwater Out
Gale Watch from Tuesday evening through late Tuesday night for
Central U.S. Waters Strait Of Juan De Fuca-East Entrance
U.S. Waters Strait Of Juan De Fuca.
Gale Warning until 3 AM PDT Tuesday for Central U.S. Waters
Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of
Juan De Fuca.
Small Craft Advisory until 3 AM PDT Tuesday for Admiralty Inlet-
Northern Inland Waters Including The San Juan Islands.
You can see an illustrated version of this discussion at