Small Craft Advisory 236, NWS Juneau, AK

422 
FZAK52 PAJK 221123
CWFAEG

Coastal Waters Forecast for Southeast Alaska
National Weather Service Juneau AK
323 AM AKDT Thu Apr 22 2021

Southeast Alaska Coastal Waters from Dixon Entrance to
Cape Suckling out 100 NM

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

PKZ099-230530-
323 AM AKDT Thu Apr 22 2021
.SYNOPSIS FOR OUTSIDE WATERS...
A ridge of high pressure over the eastern Gulf of Alaska will 
weaken today. High pressure over the Yukon and a low pressure 
trough over the Panhandle will maintain a strong northerly 
pressure gradient over the inner channels through Friday night. 

$$

PKZ041-230530-
Dixon Entrance to Cape Decision-
323 AM AKDT Thu Apr 22 2021

.TODAY...N wind 10 kt. Seas 5 ft. 
.TONIGHT...NW wind 10 kt. Seas 5 ft. 
.FRI...NE wind 10 kt. Seas 5 ft. 
.FRI NIGHT...NE wind 20 kt. Seas 7 ft. 
.SAT...NE wind 15 kt. Seas 6 ft. 
.SUN...N wind 10 kt. Seas 6 ft. 
.MON...W wind 10 kt. Seas 6 ft. 

$$

PKZ042-230530-
Cape Decision to Cape Edgecumbe-
323 AM AKDT Thu Apr 22 2021

.TODAY...N wind 10 kt becoming E. Seas 6 ft. SW swell. 
.TONIGHT...NE wind 15 kt. Seas 5 ft. 
.FRI...NE wind 15 kt. Seas 5 ft. 
.FRI NIGHT...NE wind 20 kt. Seas 7 ft. 
.SAT...NE wind 15 kt. Seas 6 ft. 
.SUN...NE wind 15 kt. Seas 6 ft. 
.MON...NW wind 15 kt. Seas 6 ft. 

$$

PKZ043-230530-
Cape Edgecumbe to Cape Fairweather-
323 AM AKDT Thu Apr 22 2021

.TODAY...E wind 10 kt. Seas 6 ft. SW swell. 
.TONIGHT...E wind 15 kt. Seas 6 ft. SW swell in the evening. 
.FRI...E wind 25 kt. Seas 6 ft. 
.FRI NIGHT...NE wind 20 kt. Seas 7 ft. 
.SAT...N wind 15 kt. Seas 6 ft. 
.SUN...NW wind 15 kt. Seas 6 ft. 
.MON...NW wind 10 kt. Seas 6 ft. 

$$

PKZ051-230530-
Cape Fairweather to Icy Cape-
323 AM AKDT Thu Apr 22 2021

.TODAY...E wind 10 kt. Seas 7 ft. S swell. 
.TONIGHT...E wind 10 kt. Seas 6 ft. S swell. 
.FRI...E wind 10 kt. Seas 5 ft. 
.FRI NIGHT...N wind 15 kt. Seas 6 ft. 
.SAT...N wind 15 kt. Seas 5 ft. 
.SUN...NW wind 10 kt. Seas 6 ft. 
.MON...NW wind 10 kt becoming E. Seas 6 ft. 

$$

PKZ052-230530-
Icy Cape to Cape Suckling-
323 AM AKDT Thu Apr 22 2021

.TODAY...SE wind 10 kt. Seas 7 ft. S swell. 
.TONIGHT...E wind 10 kt. Seas 6 ft. S swell. 
.FRI...E wind 10 kt. Seas 5 ft. 
.FRI NIGHT...N wind 10 kt. Seas 5 ft. 
.SAT...NW wind 10 kt. Seas 5 ft. 
.SUN...W wind 10 kt. Seas 5 ft. 
.MON...NW wind 15 kt becoming E. Seas 6 ft. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
241 PM AKDT Wed Apr 21 2021

.SHORT TERM...Clear skies and no precipitation will continue for
this short term forecast period. Daytime highs will trend a few
degrees above normal for this time of the year, but still feel
cool compared to last weekend and earlier this week. The clear
skies will also allow for overnight lows to fall below freezing
for most locations tonight, which is a few degrees below normal.
Highs and lows will both trend gradually warmer through the short
term period. High pressure over the Yukon will act in conjunction
with an inverted trough oriented along the long axis of the
Panhandle to maintain a moderate strength northerly pressure
gradient. Small craft winds over Lynn Canal this afternoon will
diminish overnight and remain in the 15 to 20 kt range through
Thursday as the gradient relaxes slightly, but jump back up to 25
kts late Thursday night and much of Friday. Daytime sea breezes
are not expected to fully develop in Haines or Skagway, but merely
act to diminish the northwesterly/northeasterly wind speeds.

A significant marine layer is not expected to reform tonight.
However, fog was included for Yakutat owing to the fact that the
dewpoint did not fall there all day today and the forecast low
will get well below the current dewpoint value. Elsewhere,
afternoon dewpoint spreads are considered sufficient to preclude
fog tonight. If anything, some frost may form.

Minimal changes were made to the previous forecast apart from
cooling the overnight lows tonight under clear skies. Forecast
confidence is above average.

.LONG TERM.../Fri through Wed as of 10 pm Tue/ Much of the
extended range period is dominated by a strong blocking upper
ridge over interior Alaska that does not move all that much
through the period. It is not until early next week that any signs
of significant change shows up and that comes in the form of the
ridge weakening and getting pushed W. The cause of this change is
two strong upper lows (one moving W from the Canadian Arctic, and
one moving E from the Southern Bering Sea) that will result in
a general upper trough over the state by the middle of next week.
Some uncertainty on timing and how the pattern change exactly
plays out so confidence for early next week is low.

So what does that mean for the panhandle? For the most part it
means dry and mostly clear weather continues through the weekend
at least as offshore flow dominates. The main change to the
forecast was for Fri through Sun with an increase in offshore
winds across the northern inner channels. Surface pressure will be
decreasing in the Gulf and southern panhandle starting on Fri
while high pressure remains nearly steady in the Yukon. Pressure
gradients along the coast mountains will increase (up to 2.5 to
3.5 mb forecast between Juneau and Skagway by Fri night and into
Sat), and northerly winds should respond (winds increased to 15
to 25 kt for Lynn Canal, parts of Stephens Passage, and even Cross
Sound at that time). Winds should start to diminish Sun as the
Yukon high weakens, but timing on the diminishing trend is a
little uncertain due to the uncertainty with the start of the upper
level pattern change early next week.

Precip is expected to start to return to the forecast next week,
but the timing of that is rather low confidence. This mainly stems
from the uncertainty in the upper level pattern shift for early
next week. Precip onset ranges from as early as Sun night to as
late as Tue with ensemble means trending toward the later timing
currently. They also differ on which direction it will be coming
from (some suggest an easterly wave while others are trending
toward a front from the S). We will continue to watch this
develop.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012-013-031-033-043-051-052.

&&

FCF/BFL/EAL

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