Small Craft Advisory 547, NWS Juneau, AK

440 
FZAK53 PAJK 141240
CWFYAK

Marine Forecast for Yakutat Bay
National Weather Service Juneau AK
340 AM AKST Sun Nov 14 2021

Coastal Waters Forecast for Yakutat Bay

Wind forecasts reflect the predominant speed and direction
expected. Sea forecasts represent the average of the highest
one-third of the combined windwave and swell height.

PKZ053-150645-
Yakutat Bay-
340 AM AKST Sun Nov 14 2021

.TODAY...NE wind 15 kt. Seas 6 ft. 
.TONIGHT...NE wind 15 kt. Seas 5 ft. 
.MON...E wind 10 kt. Seas 4 ft. 
.MON NIGHT...E wind 15 kt. Seas 4 ft. 
.TUE...NE wind 25 kt. Seas 5 ft. 
.WED...NE wind 20 kt becoming S 10 kt. Seas 8 ft. 
.THU...NE wind 15 kt. Seas 6 ft. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
546 AM AKST Sat Nov 13 2021

.SHORT TERM.../Through Sunday night/A cold upper low parked
across the western Gulf of Alaska supports light shower activity
across the Panhandle on this Saturday morning. Precipitation has
been generally light, but Yakutat has picked up a few hundredths.
With temperatures marginally around the freezing point and at
least some vertical motion in the snow growth zone (the layer
between between -10 and -20 C), there is some measure of
confidence that the Yakutat area will see advisory snow amounts
given training from the southwest. Darkness has prevented much
information from being extracted off area webcams, but METAR
observations from the PAYA ASOS  have consistently registered
less than 1SM to 4SM visibility from 1045Z onward. Elsewhere,
southerly flow and slightly warmer 850 temperatures than farther
west have kept temperatures warmer--from the mid 30s up to lower
40s. Hence we began most locations as rain showers rather than a
mix, and held off introduction of snow mixing in until the
afternoon for the north. A boundary setting up from a vorticity
band from the Alsek River south-southwest would appear to
separate the cold air from the milder air to the west. And this
vorticity band is not forecast to push much farther westward
through the next 24 hours. Therefore, confidence in a mix to snow
might have fallen a bit as consensus on 850 temperature trends
through this afternoon sadly is absent. Whatever the case,
accumulations across the Panhandle with the exception of the
Haines and South Klondike Highways and Yakutat should be light to
nothing given temperatures well into the 30s and not significantly
cooling until tonight.

Southerly and westerly small crafts through the northern Inner
Channels ease through the day just as seas also fall across the
gulf through tonight. With one last wave arriving over the Inner
Channels this afternoon, there could be some brief breezy
conditions developing through the passages but confidence is not
high. Finally, we added some isolated thunder between Cape
Fairweather and Yakutat Bay this morning to account for the
enhanced lift of the vorticity band and steep lapse rates across
the northeast gulf.

Tonight a wave forming in the northwest gulf swings wide into the
southeast gulf and offshore flow begins to develop in response,
particularly across the northern Panhandle. Showers in the north
all but end this evening and temperatures begin to chill. Showers
across the south remain and as thicknesses fall towards marginal
levels, some areas may experience a changeover, particularly in
the higher elevations. But accumulations should be light.

Our upcoming issue to solve is a developing outflow regime and
how strong winds become. North-south gradients push towards 5 mb
between Skagway and Juneau between early Sunday morning and
Monday, suggesting low-end gales are possible. But mountain wave
guidance for Downtown Juneau/Douglas does not flag cross barrier
flow as a significant ingredient for any outflow associated
mountain wave event. Upon closer inspection, gradients are much
tighter north-south, than northeast-southwest. Therefore, we
lowered wind speeds through Downtown Juneau a bit. Temperatures
are also something to watch for the next few days with a colder
air mass filtering in from Canada. We expect mid to upper 20s
across the north with low to mid 30s over the south Sunday
morning. By Monday morning, 20s sink as far south as Petersburg.
with the threat of freezing temperatures for the southern
Panhandle. White Pass will experience lows in the single digits
Monday morning.

.LONG TERM.../ Monday through Saturday as of 10 PM Friday /
Clearing skies will dominate across the N half of the panhandle
through much of Monday, the result of an outflow event. The
responsibility for the outflow event lies in the strengthening
pressure gradient across the area as a new low moving N out of
the southern Gulf interacts with a high in the Yukon. Expect that
with this outflow event, it is likely that breezy conditions will
be seen across at least the N half of the panhandle. Lynn Canal
will likely see gale force winds, and have kept small craft winds
in through many of the central inner channels. There may also be
an opportunity for a weak mountain wave event to setup over
downtown Juneau, though am not yet confident in this given the
differences in timing of the low to the south. Conditions are
likely not to be wholly ideal for strong mountain wave activity,
but with fall fast giving way to winter, it is looking
increasingly likely that at least some of the prerequisites could
be present.

The windy conditions will most likely begin to subside Monday
afternoon through Monday night as the low in the south attempts to
advance into the panhandle, before being deflected back to the S
as its associated trough moves out of the area. Still some
difficulties with determining the exact track, as the low may be
less of a single feature, but instead multiple waves within a
broader area of circulation, but it still looks like the southern
panhandle will experience the bulk of any significant
precipitation with this system. The far N panhandle will likely
stay fairly dry with precip chances slowly increasing through the
Icy Strait Corridor on South.

Somewhat better agreement between models and operational
agreements which indicate that the low will likely depart the area
by Tuesday. Cooler air will have a chance to filter back in behind
the low, which could lead to a potential snow event as another
system arrives later on Tuesday or Wednesday. A significant number
of individual ensemble runs indicate that much of SE AK, including
Juneau, could receive notable measurable snow from this system.
As is often the case when looking this far out, forecast
uncertainty means this is not yet set in stone.

Looking even further afield, there continue to be hints that
a significant cool down for late next week could be in the works
across the northern half of the area- something which would
likely be joined with a substantial outflow event. However,
confidence in this event remains low at this time.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory until 3 PM AKST this afternoon for
     AKZ017.
MARINE...Small Craft Advisory for PKZ012-022-041>043-051-052.

&&

JWA/GFS

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