Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
FXUS66 KSEW 311025
Area Forecast Discussion
National Weather Service Seattle WA
325 AM PDT WED AUG 31 2016
.SYNOPSIS...A cold front will slowly move inland today for a
little rain. An upper level trough will maintain cooler weather
with a chance of showers from Thursday into early next week.
.SHORT TERM...A slow moving cold front will drag across Western
Washington today for a little rain. The front and the
precipitation has been mainly along the coast this morning and
will shift east into the interior this afternoon. Rainfall amounts
in the interior will be generally less than 0.10 inches. The coast
will see 0.10 to 0.50 inches.
A blocking ridge over the central U.S. will keep low pressure over
the Pac NW Thursday and Friday. This pattern will maintain cool
and showery weather across Western Washington with below normal
temperatures. Friday`s highs will only reach the low to mid 60s.
The ridge over the central U.S. will weaken a bit and shift east
as we move into Saturday. But a long wave trough will remain over
the West for more cool and unstable conditions across Western
Washington. POPs are less across the area but could still see
isolated to scattered showers through the day. 33
.LONG TERM...A strong upper level ridge will build over the NE
Pacific early next week with the flow aloft turning northerly over
Western Washington. Models are showing a break in the action on
Sunday which is consistent with the new solutions. The flow aloft
will then turn more NW to W Monday and Tuesday as the offshore
ridge flattens. This opens the door as a series of upper level
disturbances track through the region. The exact timing of each
wave is still unclear but there is at least a chance of showers
through the period. Temperatures will remain slightly below
.AVIATION...Upper level trough offshore moving inland tonight.
Southwesterly flow aloft becoming westerly tonight. A weakening cold
front will move through the area today.
Ceilings near 5000 feet over the interior early this morning will
lower down to near 3500 feet with the onset of precipitation later
this morning into the afternoon hours. Ceilings along the coast will
be lower...1000 to 2000 feet with local ceilings below 1000 feet and
visibilities 1-3sm in rain. Front east of the area in the afternoon
with ceilings improving along the coast. Little change in the
ceilings over the interior into Thursday morning.
KSEA...5000 foot ceilings just to the west of the terminal at
10z/3am. 5000 foot deck will spread over the terminal by 14z.
Ceilings continuing to lower to near 3500 feet by late morning.
Little change in the ceilings afternoon and evening hours.
Southeasterly winds 5 to 10 knots becoming southerly this
.MARINE...A cold front over the coastal waters will move inland
this morning. the front will be east of the waters this afternoon.
A small craft advisory remains in effect for the coastal waters this
morning but the inland waters are only likely to see south
southeasterly winds up to about 15 knots.
The next front should arrive Thursday afternoon and night with
another round of small craft advisory strength winds possible for
the coastal waters. Onshore flow will develop on Friday and continue
into the weekend. Felton
PZ...Small Craft Advisory until 2 PM PDT this afternoon for Coastal
Waters From Cape Flattery To James Island 10 To 60 Nm-
Coastal Waters From Cape Flattery To James Island Out 10 Nm-
Coastal Waters From James Island To Point Grenville 10 To
60 Nm-Coastal Waters From James Island To Point Grenville
Out 10 Nm-Coastal Waters From Point Grenville To Cape
Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville
To Cape Shoalwater Out 10 Nm.
You can see an illustrated version of this discussion at