Small Craft Advisory 246, NWS Juneau, AK

617 
FZAK53 PAJK 281223
CWFYAK

Marine Forecast for Yakutat Bay
National Weather Service Juneau AK
423 AM AKDT Wed Apr 28 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.

PKZ053-290630-
Yakutat Bay-
423 AM AKDT Wed Apr 28 2021

.TODAY...E wind 10 kt. Seas 7 ft. SW swell early in the morning. 
.TONIGHT...E wind 10 kt. Seas 6 ft. 
.THU...Light winds becoming NE 10 kt in the afternoon. Seas
5 ft. 
.THU NIGHT...E wind 10 kt. Seas 4 ft. 
.FRI...SE wind 10 kt becoming light. Seas 5 ft. 
.SAT...Light winds. Seas 5 ft. 
.SUN...Light winds becoming E 10 kt. Seas 5 ft. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
241 PM AKDT Tue Apr 27 2021

SHORT TERM.../Through Wed night/ A surface low is sitting in the
gulf pushing warm and moist air into the region and will linger
there for the next couple of days. Areas across the panhandle are
already seeing rain from this system. Heaviest amounts of
precipitation from this potentially record breaking system are
expected Thursday.

Overall changes include increasing the chances of precipitation
in the northern panhandle and adjusting some timing of when the
precipitation will occur. There will be a short break in heavy
rainfall early tomorrow, before it picks back up again, first in
the south and then moving northwards through the day. Looking at
48 hour totals, over 2 inches of accumulated precipitation is
forecasted through Wednesday and Thursday for most of the Southern
Panhandle and Juneau. Ketchikan and portions of Prince of Wales
may receive over 3 inches of precipitation in 48 hours.

No significant changes were made to the winds and minor changes
were made to the temperatures. Cloud coverage will result in
temperatures not falling as low as was initially forecasted, so
the mention of snow and the mix of rain and snow was removed from
the Juneau area. Skagway and Haines will keep a slight chance of
snow tonight.

LONG TERM.../Thursday through Tuesday as of 10 pm Monday/

A wetter pattern continues in the long term with the main weather
maker impacting the region Thursday into Friday. The start of the
period features deep troughing over the gulf which will weaken and
lift north as ridging builds into the Gulf by Sunday. At the
surface, a low remains in the SW gulf with a strong wave rotating
around it through the eastern gulf Thursday. Both lows weaken and
merge into a broad trough in the northern gulf by the weekend
before high pressure builds into the gulf.

The main forecast challenge in the long term is the exact track
of the wave on Thursday. All deterministic models show a general
low moving north through the eastern gulf Thursday morning through
Friday morning; however the track and strength have not been
consistent run to run. EC ensembles have been more consistent with
the details of this system and WPC favored the ECMWF for any
forecast changes this evening, therefore blended heavily towards
that solution. The current forecast is for a broader, weaker
complex surface low to move northward through the eastern Gulf
Thursday then retrograde NW toward the northern Gulf coast Friday.
Ahead of the low, expect small craft conditions to develop in the
southern Coastal Waters, Dixon Entrance and Clarence Strait, and
out of Cross Sound. Still thinking Gulf winds may be a little too
weak for this timeframe; however am not confident enough to
increase them to gales with so much model inconsistencies at the
moment.

This next system is also expected to bring copious amounts of
moisture into Southern and Central Panhandle as strong southerly
flow at all levels pumps in moist subtropical air. EC ensembles
have IVT values over 500 kg/m/s, 4 standard deviations above
normal for this time of year. The EC EFI also highlights much of
the Panhandle for QPF at the higher end of the model's climatology
with great ensemble support. Confidence is increasing in a heavy
rainfall event for the Central and Southern Panhandle beginning
Wednesday evening and continuing through late Thursday night.
Current 48 hour (Through Fri morning) QPF ranges from 2 to 4
inches across the Southern Panhandle to 1 to 2 inches across the
Central and Northern Panhandle. Higher confidence is with the
precip forecast rather than the wind forecast; however do expect
some QPF changes over the next few days as models come into
better agreement on the track and strength of the low.

More "tranquil" conditions develop behind the departing system as
ridging builds over the Gulf and into the Panhandle. Onshore flow
still exists so expect shower activity to persist, diminishing in
coverage and intensity through the weekend. Expect southwesterly
winds Friday to diminish through the weekend as well as weak
ridging builds in and the pressure gradient relaxes. Confidence
drops significantly early next week as ensembles and models
diverge on the next system moving into the region. The general
consensus is for a broad area of low pressure to move back into
the gulf keeping the wetter, unsettled weather around.

Blended heavily with the ECMWF through the first half of the short
term then trended towards WPC for the latter half. Confidence is
increasing in a heavy rainfall event Thursday for the southern
half of the Panhandle. Lower confidence exists for early next
week.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ022-035-036-041>043-051>053.

&&

KRT/CM

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