Gale Warning 5, NWS Juneau, AK

870 
FZAK67 PAJK 122343
OFFAJK

Offshore Waters Forecast
National Weather Service Juneau AK
243 PM AKST Tue Jan 12 2021

Offshore waters forecast for Gulf of Alaska east of 144W

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.

PKZ398-131745-
243 PM AKST Tue Jan 12 2021
.SYNOPSIS FOR THE EASTERN GULF OF ALASKA...
A weakening low departs the panhandle Tuesday night. Ridging 
builds over the area Wednesday. A storm force low arrives in the 
eastern gulf on Thursday. 

$$

PKZ310-131745-
Gulf of Alaska North of 55 Degrees North and East of 144 Degrees
West-
243 PM AKST Tue Jan 12 2021

.TONIGHT...SW wind 20 kt. Seas 14 ft. SW swell in the evening. 
.WED...SW wind 25 kt. Seas 13 ft. SW swell. 
.WED NIGHT...S wind 20 kt becoming E gale to 45 kt late.
Seas 14 ft. SW swell in the evening. 
.THU...SE storm force wind to 55 kt. Seas 25 ft. Rain...
heavy at times. 
.THU NIGHT...S gale to 40 kt diminishing to 25 kt late. Seas
27 ft. Rain in the evening. 
.FRI...S wind 25 kt. Seas 23 ft. 
.SAT...S wind 25 kt. Seas 20 ft. 
.SUN...SE wind 25 kt. Seas 21 ft. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
317 AM AKST Tue Jan 12 2021

.UPDATE...Salmon Landing observations reached 55 mph and with the
peak wind time projected for Ketchikan between 12Z and 15Z, we
decided to post a high wind warning for the southern Inner
Channels through 7 AM. All of this bolsters our confidence for
western Prince of Wales which is closer to the storm center. But
it forces us to take a serious look at Baranof Island. But for
now, we still think winds should weaken sufficiently for fewer and
less serious impacts.

&&

.PREV DISCUSSION......ISSUED AT ...145 AM AKST TUE JAN 12 2021

UPDATE...We posted a high wind warning for western Prince of
Wales Island through 9 AM. Widespread gust of around 65 mph have
occurred at various observation points along both sides of Haida
Gwaii. Also Ketchikan gusts around midnight were already
exceeding forecast. The best time period for the high winds will
be from 2 AM to 7 AM. All models have indicated the system arrives
later than we thought yesterday. We examined the potential for
Sitka, but for now, have elected to keep the current wind gusts of
50 mph, as models all indicate weakening as it churns north
offshore of Baranof Island. Timing of winds for Sitka will now be
midday Tuesday, between 10 AM and 2 PM. We also kept winds going
longer for Ketchikan and the southern Inner Channels as well as
Petersburg, Kake, Wrangell area. Likewise, we updated the
forecasts for the central Inner Channels to reflect a later
arrival and keep lighter north winds blowing longer. Some leftover
snow will likely not happen, but as current snowfall
accumulations were zero, we did not remove to save time on a
precariously inconvenient issue time.

PREV DISCUSSION......ISSUED AT ...309 PM AKST Mon Jan 11 2021

SHORT TERM.../Through Wed night/ Southerly flow and showers are
the main rule of the day today. some of these showers have been a
little intense as far as rainfall is concerned, but they have been
lacking in lightning. Only one strike near Sitka was detected
overnight and a few just S of Yakutat around 2 pm but that has
been it so far.

The main focus of the short range is the compact and strong low
that will be coming up along the outer coast tonight into
tomorrow. Main concern is how much wind is this thing going to
produce. 925 mb low level jet of around 55 to 62 kt, particularly
on the S side of the low in the Southwesterlies. Gusts of 40 to
50 mph are expected for many areas of the panhandle from Juneau
and Elfin Cove southward tonight into tomorrow. Whether some areas
will get high wind gusts to 60 mph is very uncertain but the
outer coastal areas of Prince of Wales and Baranof islands will be
the most likely places to get it in the SW flow behind the low.
Opted to stay below high wind criteria for now, but still have
gusts approaching 55 mph in the strong SW flow behind the low.
Gales and wide spread small craft winds will also be a common
feature for many gulf and inner channel marine areas as well. The
northern inner channels will likely get in on the act by Tue
afternoon as well as the pressure gradient suddenly flips south in
the wake of the low.

Another period of precipitation is in the works for the panhandle
with this low as well. Most areas will be warm enough for rain
except for possibly the higher elevations of the Klondike. However
with this system moving through rather quickly. Precip amounts are
expected to be rather low.

Behind this low SW onshore flow and showers resumes with a gradual
decreasing trend into Wed night. Atmospheric instability does not
appear to be as strong as it is with the current shower activity
so the showers should not be as intense as todays are.

LONG TERM.../Wednesday through Monday night/...The long range
forecast period begins with a large upper low centered over
Bristol Bay, a much weaker upper circulation west of Haida Gwaii,
and a very broad upper trough which encompasses both of these
features. The base of the trough extends from the dateline east to
the west coast of southern British Columbia with the trough axis
extending south to 40N. A very strong 190kt upper jet associated
with this trough will begin to dig south of the Aleutians early in
the period, sharpening up the trough axis and inducing a
negatively tilted upper ridge across the southern Gulf by
Wednesday afternoon. This will produce a new upper low which will
take up a position over the western central Gulf by Friday
morning. As this happens, the upper ridge will continue to build
and then be displaced to the east as a trough axis pivots north
about the new low. The upper low will retrograde northwest and
become absorbed in the upper flow as large scale onshore flow
dominates the eastern Gulf Friday night heading into Saturday. The
extended range forecast will end with another upper low
approaching the central Gulf from the southwest Sunday through
early next week.

At the surface, a southwest flow pattern sets up over the entire
region with a surface low located around Bristol Bay. The next
impactful system moves northward into the gulf on Thursday with a
low heading towards Kodiak Island and an associated gale force
front pushing into the Panhandle. The parade of storm systems
continue through early next week with a series of lows moving
into the gulf, following almost the same track and swinging strong
fronts into the coast.

The sensible weather pattern will continue to be wet, as is
typical for this time of the year, with multiple fronts and waves
bringing plenty of precipitation. The general onshore pattern will
provide for continued warmer (relatively speaking) air such that
the precip type will be predominantly rain for lower elevations
except the far northern inner channels. There, daytime rain will
periodically give way to overnight snow. Only the highways will
remain reliably cold enough for consistent snow.

Overall model agreement is good for the long term regarding the
general weather pattern. However, there are disagreements between
models regarding the finer details of the forecast, which is to
be expected this far out. Used a blend of EC/Canadian for winds
and timing of the front on Thursday, which brings it in 6 hours
faster than the GFS. The exact timing and details of the next
systems moving in for the weekend and early next week will be
worked through in the coming days as models come into better
agreement. Trended towards WPC for the latter part of the long
term, which heavily used the EC and EC ensembles. Despite model
differences, there is high confidence that this wet and warmer
pattern will continue into next week.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind until noon AKST today for AKZ026.
     High Wind Warning until 9 AM AKST this morning for AKZ027.
     Strong Wind through this afternoon for AKZ023-025.
     High Wind Warning until 7 AM AKST this morning for AKZ028.
     Strong Wind this afternoon for AKZ018-019.
MARINE...Storm Warning for PKZ041-042.
     Gale Warning for PKZ012-013-031>036-043.
     Small Craft Advisory for PKZ011-021-022-051>053.

&&

JWA/JWA/EAL/FRITSCH

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