Small Craft Advisory 272, NWS Juneau, AK

425 
FZAK52 PAJK 172336
CWFAEG

Coastal Waters Forecast for Southeast Alaska
National Weather Service Juneau AK
336 PM AKDT Mon May 17 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.

PKZ099-181745-
336 PM AKDT Mon May 17 2021
.SYNOPSIS FOR OUTSIDE WATERS...
A broad ridge will build over the gulf through Wednesday.   

$$

PKZ041-181745-
Dixon Entrance to Cape Decision-
336 PM AKDT Mon May 17 2021

.TONIGHT...NW wind increasing to 20 kt in the evening. Seas 7 ft.
W swell.
.TUE...NW wind 20 kt. Seas 7 ft. 
.TUE NIGHT...NW wind 20 kt. Seas 6 ft. 
.WED...NW wind 15 kt. Seas 5 ft. 
.WED NIGHT...NW wind 15 kt. Seas 5 ft. 
.THU...W wind 10 kt becoming S. Seas 5 ft. 
.FRI...S wind 25 kt. Seas 9 ft. 
.SAT...S wind 10 kt. Seas 7 ft. 

$$

PKZ042-181745-
Cape Decision to Cape Edgecumbe-
336 PM AKDT Mon May 17 2021

.TONIGHT...NW wind increasing to 20 kt in the evening. Seas 6 ft.
W swell.
.TUE...NW wind 20 kt. Seas 6 ft. 
.TUE NIGHT...NW wind 20 kt. Seas 6 ft. 
.WED...NW wind 15 kt. Seas 5 ft. 
.WED NIGHT...W wind 15 kt. Seas 4 ft. 
.THU...S wind 15 kt. Seas 6 ft. 
.FRI...SE wind 25 kt. Seas 10 ft. 
.SAT...S wind 10 kt. Seas 7 ft. 

$$

PKZ043-181745-
Cape Edgecumbe to Cape Fairweather-
336 PM AKDT Mon May 17 2021

.TONIGHT...NW wind increasing to 20 kt in the evening. Seas 5 ft.
.TUE...NW wind 15 kt. Seas 5 ft. 
.TUE NIGHT...W wind 15 kt. Seas 5 ft. 
.WED...W wind 15 kt. Seas 4 ft. 
.WED NIGHT...SW wind 10 kt. Seas 3 ft. 
.THU...SE wind 15 kt. Seas 5 ft building to 8 ft. 
.FRI...SE wind 25 kt. Seas 11 ft. 
.SAT...S wind 15 kt. Seas 7 ft. 

$$

PKZ051-181745-
Cape Fairweather to Icy Cape-
336 PM AKDT Mon May 17 2021

.TONIGHT...NW wind 15 kt. Seas 4 ft. 
.TUE...W wind 15 kt. Seas 4 ft. 
.TUE NIGHT...W wind 15 kt. Seas 4 ft. 
.WED...W wind 10 kt. Seas 4 ft. 
.WED NIGHT...SE wind 10 kt. Seas 3 ft. 
.THU...SE wind 20 kt. Seas 8 ft. 
.FRI...SE wind 25 kt. Seas 11 ft. 
.SAT...SE wind 15 kt. Seas 8 ft. 

$$

PKZ052-181745-
Icy Cape to Cape Suckling-
336 PM AKDT Mon May 17 2021

.TONIGHT...W wind 15 kt. Seas 5 ft. 
.TUE...W wind 10 kt. Seas 4 ft. 
.TUE NIGHT...W wind 15 kt. Seas 4 ft. 
.WED...W wind 10 kt. Seas 3 ft. 
.WED NIGHT...SE wind 10 kt. Seas 4 ft. 
.THU...SE wind 25 kt. Seas 7 ft building to 11 ft. 
.FRI...E wind 30 kt. Seas 12 ft. 
.SAT...SE wind 15 kt. Seas 9 ft. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
253 PM AKDT Sun May 16 2021

.SHORT TERM.../Through Tuesday evening/ A welcomed drying trend
begins in the short term as higher pressure over the gulf
influences the region. This evening, ridging exists over the
Panhandle while a weak upper low in the far southern gulf slowly
moves east. This low will remain south of the Panhandle as it
traverses the gulf while high pressure builds in its place.

The main forecast challenge during this period will be frost and
fog potential during the morning hours. Light winds combined with
diminishing showers and cloud cover may allow for fog and/or
frost to develop in some areas late tonight through tomorrow
morning. With dew points already in the 30s for most places,
temps dropping into the low to mid 30s tonight should be
attainable if good radiational cooling takes place. Have issued a
Frost Advisory from 2am to 8am tomorrow for areas where there is a
higher confidence in frost formation (Haines HWY, Mendenhall
Valley, Hoonah, Kake, Petersburg, and Hyder). Frost may also form
in other valleys and wind sheltered areas. Fog may also be an
issue tonight; however confidence remains low regarding exact
locations. Any place that is wind sheltered, has a moist
boundary layer, and partially clearing skies has the potential
for patchy fog. This will be monitored closely tonight.

Weak onshore flow will switch around to the north Monday,
allowing much of the Panhandle to dry out. There is a slight
chance of a few afternoon pop up showers around higher terrain in
the Southern Panhandle and along the Coast Mountains, but for the
most part tomorrow should be dry. Mostly cloudy skies will
slowly break up becoming partly cloudy by tomorrow afternoon.
Expect light northerlies through most water ways with the
exception of the outer coast as winds increase to 15 to 20 kt.
High temperatures are expected to be around average for this time
of year in the 50s areawide.

Expect similar conditions Tuesday as weak offshore flow and a
high over the gulf keep the area mostly dry. There is the
potential for showers to reach Hyder Tuesday afternoon as a weak
wave persists in Central BC. Lower pressure on the Canadian side
of the Coast Mountains and destabilization from afternoon heating
may allow for afternoon convection to develop along the
US/Canadian border and White Pass; however have not included
thunder wording in the forecast at this time. Expect Tuesday to be
the warmest day in the short term as 850 mb temps warm from
around -2C to +2C. Warmer air aloft and slight downsloping should
allow for afternoon temperatures to rise into the upper 50s and
low 60s for most places.

Overall confidence is around average. Lower confidence exists in
the fog/frost potential through early tomorrow morning.

.LONG TERM.../Tuesday to Sunday as of 10 pm Saturday/ High
pressure builds over the AK Gulf mid week, then extending over
most of the area. Break down of ridge late in the week and into
the weekend allowing upstream waves near the Aleutians to track
east. Dry weather for the start of the period with potential for
rain moving in towards the weekend with the advancing lows. In
addition to possible rain, have warmer air moving in resulting in
increasing temperatures through the extended range. Overall light
winds under the ridge then small craft winds over the gulf under
advancing front. No indications of significant weather from
standardized anomaly and EFI tables. Still large model spread
between ensembles and operational models. Example: operational
ECMWF more robust in moving in precipitation late in the week
while the GFS has any front breaking apart by the time it reaches
the Eastern Gulf and shifts low centers to the south. The multiple
streams in the upstream jet is the likely cause for this
complicated pattern which has been around for several days
running. Made little change to the inherited forecast due to
uncertainty, so keeping the typical SE Alaska weather of mostly
cloudy chance of rain until something clearer comes around.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Frost Advisory from 2 AM to 8 AM AKDT Monday for Akz017-021-025-
026-029. MARINE...Small Craft Advisory for PCs.

&&

CM/PRB

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