Small Craft Advisory 308, NWS Juneau, AK

107 
FZAK52 PAJK 222332
CWFAEG

Coastal Waters Forecast for Southeast Alaska
National Weather Service Juneau AK
332 PM AKDT Tue Jun 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.

PKZ099-231745-
332 PM AKDT Tue Jun 22 2021
.SYNOPSIS FOR OUTSIDE WATERS...
A ridge over the southern Panhandle will persist through Wed,
before shifting eastwards into western British Columbia. A gale
force front will move into the eastern Gulf from the SW Wed and
into the Panhandle Wed night.  

$$

PKZ041-231745-
Dixon Entrance to Cape Decision-
332 PM AKDT Tue Jun 22 2021

.TONIGHT...NW wind 10 kt diminishing, then becoming SE 15 kt late.
Seas 5 ft.
.WED...S wind 15 kt. Seas 7 ft. Rain.
.WED NIGHT...S wind 30 kt. Seas 11 ft. Rain.
.THU...S wind 25 kt. Seas 11 ft. 
.THU NIGHT...S wind 20 kt. Seas 10 ft. 
.FRI...SW wind 15 kt. Seas 9 ft. 
.SAT...SW wind 10 kt becoming NW. Seas 7 ft. 
.SUN...NW wind 15 kt increasing to 25 kt. Seas 7 ft. 

$$

PKZ042-231745-
Cape Decision to Cape Edgecumbe-
332 PM AKDT Tue Jun 22 2021

...SMALL CRAFT ADVISORY WEDNESDAY...

.TONIGHT...NW wind 10 kt diminishing, then becoming SE 15 kt late.
Seas 6 ft.
.WED...SE wind 20 kt increasing to 30 kt in the afternoon.
Seas 8 ft. Rain in the afternoon. 
.WED NIGHT...S wind 30 kt. Seas 12 ft. Rain.
.THU...S wind 25 kt. Seas 11 ft. 
.THU NIGHT...S wind 20 kt. Seas 10 ft. 
.FRI...S wind 15 kt. Seas 8 ft. 
.SAT...S wind 10 kt becoming NW. Seas 8 ft. 
.SUN...NW wind 15 kt increasing to 25 kt. Seas 7 ft. 

$$

PKZ043-231745-
Cape Edgecumbe to Cape Fairweather-
332 PM AKDT Tue Jun 22 2021

...SMALL CRAFT ADVISORY WEDNESDAY...

.TONIGHT...Light winds becoming SE 15 kt late. Seas 6 ft. 
.WED...SE wind 20 kt increasing to 30 kt in the afternoon.
Seas 8 ft building to 12 ft in the afternoon. Rain in the
afternoon. 
.WED NIGHT...SE gale to 35 kt. Seas 14 ft. Rain.
.THU...S wind 25 kt. Seas 11 ft. 
.THU NIGHT...S wind 20 kt. Seas 10 ft. 
.FRI...S wind 15 kt. Seas 9 ft. 
.SAT...S wind 10 kt becoming NW. Seas 8 ft. 
.SUN...NW wind 20 kt. Seas 7 ft. 

$$

PKZ051-231745-
Cape Fairweather to Icy Cape-
332 PM AKDT Tue Jun 22 2021

...SMALL CRAFT ADVISORY WEDNESDAY...

.TONIGHT...Light winds becoming SE 15 kt late. Seas 5 ft. 
.WED...E wind 20 kt becoming SE 30 kt in the afternoon.
Seas 7 ft building to 13 ft in the afternoon. Rain in the
afternoon. 
.WED NIGHT...SE gale to 35 kt. Seas 15 ft. Rain.
.THU...SE wind 25 kt. Seas 12 ft. Rain.
.THU NIGHT...SE wind 20 kt. Seas 10 ft. 
.FRI...S wind 15 kt. Seas 8 ft. 
.SAT...S wind 10 kt becoming NW. Seas 8 ft. 
.SUN...NW wind 20 kt. Seas 6 ft. 

$$

PKZ052-231745-
Icy Cape to Cape Suckling-
332 PM AKDT Tue Jun 22 2021

...GALE WARNING WEDNESDAY...

.TONIGHT...SE wind 10 kt increasing to 20 kt late. Seas 6 ft. 
.WED...E wind 25 kt increasing to 40 kt in the afternoon.
Seas 7 ft building to 15 ft in the afternoon. Rain in the
afternoon. 
.WED NIGHT...SE gale to 35 kt. Seas 16 ft. Rain.
.THU...SE wind 25 kt. Seas 12 ft. 
.THU NIGHT...SE wind 20 kt. Seas 10 ft. 
.FRI...SE wind 20 kt. Seas 8 ft. 
.SAT...SE wind 15 kt becoming W. Seas 8 ft. 
.SUN...W wind 15 kt. Seas 6 ft. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
241 PM AKDT Mon Jun 21 2021

.SHORT TERM.../Through Wednesday/ Damp and cloudy day across the
panhandle as onshore flow continues to bring a moist air mass into
the area following last night's front. 24 hour rainfall reached 1
to 2 inches in parts of the Juneau, Glacier Bay, and Yakutat
areas overnight. Area rivers and streams did respond, but still
remain well below bankfull at this time. Some wind was also
observed with the front, but mostly was 20 kt or less. Some gusty
winds are still being felt in the Lynn Canal/Skagway area where
southerly winds of 20 kt continue to blow this afternoon.

The next 24 hours will be the calm before the next strong system
moves in. Showers should shut off on Tue as the ridge over the
southern panhandle moves just far enough W to shut off the onshore
flow feeding them. Cloud cover will still likely be around, but
some areas may see some breaks every now and then.

All eyes are on Wed and Wed night though as a strong summer storm
moves in from the SW. Gale force winds are expected for the
northern Gulf from Cape Spencer westward Wed with 20 to 30 kt
winds for the rest of the gulf. Those winds will spread into the
inner channels Wed night with most areas seeing 15 to 25 kt winds
as the front moves through. Main forecast changes were an increase
in some inner channels winds as the front comes inland Wed night
into Thu compared to what was in the forecast previously. Heavy
rain will also be likely with a moderate to strong atmospheric
river pointed at the panhandle. IVT and IWV guidance shows
Moderate to high values aimed at the panhandle starting Wed night.
Rain will likely start up late Wed afternoon or Wed evening for
most areas. Forecast changes here were a slight decrease in
expected QPF and a slower trend on the timing of when the rain
starts up, but the overall forecast remains rather wet.

.LONG TERM.../Wednesday through next Monday/...The mid-week event
continues to provide the focus for our mid-range forecast. An
unseasonably deep upper low finds anchor in the western gulf and
Bristol Bay region midweek and aims a deep swath of moisture
towards Southeast Alaska. Ensembles all present a time period from
06Z Thu to roughly 12Z Fri when integrated vapor transport is
strongest (between 500 and 750 kg/m/s). This increases the
concerns from 24 hours ago as consensus then held that this
atmospheric river would be intense, yes, but more brief in
duration. Now the majority of ensemble members point to a greater
duration. From Wednesday morning through Friday morning, 48 hour
rainfall amounts look to fall in the 2 to 4 inch range from
Baranof Island including Sitka, northwest to Pelican and Elfin
Cove and then east to Gustavus and Juneau. Three to five inches
could drop over the Yakutat and the northeast Gulf Coast. Most
other areas of the Panhandle still could receive 1 to 2 inches. A
special weather statement has been posted for heavy rain and
significant rises for area rivers. While flooding is not
anticipated, we will continue to coordinate with RFC on any
foreseeable impacts. Fortunately, this mid-week event will be
somewhat mitigated by a break in the weather on Tuesday that will
allow saturated ground a period of recovery.

Winds will be another concern as we did boost the southeast winds
to 40 kt for the outside waters with the initial front Wednesday
night. Likewise we did begin raising the Inner Channels to 15 to
20 kt. Small craft advisories are definitely a possibility, but
where/when and how strong are not completely known at this point.
Breezy conditions likely will need expanded from the coast into
communities on the inside.

Furthermore, we lowered high temperatures on both Wednesday and
Thursday to keep temperatures in the 50s all day during the heavy
rain. Looking onward into the weekend, there are still signs of a
building ridge across the eastern gulf with an ensemble-indicated
500-mb ridge axis inching westward with successive model runs.
This still means potentially warmer and drier weather just in time
for next weekend.

&&

.HYDROLOGY...Mendenhall Lake showed a notable rise overnight (it
is still a good 2.5 feet below flood stage however), mainly from
the heavy rainfall that occurred. However, webcam images from
Suicide Basin show a slow, but noticeable fall in water levels in
the basin since about Sat. There are no indications of any
significant release of water from Suicide Basin yet, and water
levels in Mendenhall Lake are leveling off as of this afternoon.
We are watching Suicide Basin closely, but the water levels in the
basin are a good 60 to 70 meters below what they peaked at in
2020 so any release at this time will be small.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...None.

&&

EAL/JWA

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