Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
FXUS66 KSEW 251608
Area Forecast Discussion
National Weather Service Seattle WA
910 AM PDT WED MAY 25 2016
.SYNOPSIS...An upper trough will a chance of showers at times
Thursday through next Monday. An upper ridge will build starting
around next Tuesday.
.SHORT TERM...There is a hole in the clouds over the Olympics,
over a good portion of the central and eastern Strait of Juan de
Fuca area and Admiralty Inlet, and also up into the San Juans.
It looks like the area of more sunshine is also trying to progress
toward the metro area too. The forecast was changed for some more
sunshine for the interior of Western Washington by afternoon.
An upper trough will work over the region for the end of the week
and that will bring with it a good chance of showers a times.
The Puget Sound convergence zone area as well as the Cascades
and foothills will have the best chance of showers or rain.
.LONG TERM...Extended models in pretty good agreement on the 00z
run with one upper level trough kicking out on Saturday being
replaced by another upper level trough moving down from the
northwest Saturday night into Sunday. This pattern will keep
showers in the forecast over the weekend. Some trofiness
remaining Memorial day morning but at this point it looks like the
trough will move east leaving a dry afternoon. Models showing good
agreement with a ridge building offshore Memorial day afternoon
into Tuesday so have gone ahead and dried out the forecast and
raised the max temperatures by a few degrees on Tuesday...into the
70s from Seattle south to Lewis county. Felton
.AVIATION...There is a weak upper trough in eastern Washington and a
ridge over the northeast Pacific. Weak northwest flow aloft. Onshore
flow at the surface. The air mass is stable with low level moisture
over most areas, though the Olympics and strait areas are mostly
Where clouds exist ceilings are mainly MVFR. There will be a lifting
and clearing trend today with mainly VFR or no ceilings by late
afternoon. MVFR stratus will return tonight.
KSEA...Ceiling near 1k ft this morning will rise to 2k ft by 19z or
so then to 3-4k ft by 00z. Ceiling will fall to MVFR by 10z.
Southwest wind 8-12 kt will swing around to west of even northwest
late in the afternoon, then return to southerly overnight. CHB
.MARINE...Onshore flow will continue through the end of the week.
Gale force westerlies are possible this evening in the strait but
for now have kept the small craft advisory with a forecast of 20-30
kt. Small craft advisories are also in effect this evening in
Admiralty Inlet and the northern inland waters. This pattern will
repeat Thursday and Friday at least and could continue into next
PZ...Small Craft Advisory for the Outer Coastal Waters...Central and
Eastern Strait...Northern Inland Waters...Admiralty Inlet.
You can see an illustrated version of this discussion at