Small Craft Advisory 135, NWS Juneau, AK

944 
FZAK53 PAJK 031302
CWFYAK

Marine Forecast for Yakutat Bay
National Weather Service Juneau AK
402 AM AKST Wed Mar 3 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.

PKZ053-040715-
Yakutat Bay-
402 AM AKST Wed Mar 3 2021

...SMALL CRAFT ADVISORY THROUGH THIS MORNING...

.TODAY...NE wind 10 kt. Seas 8 ft. SW swell. Snow showers, rain
showers and isolated thunderstorms early in the morning. 
.TONIGHT...NE wind 15 kt. Seas 7 ft. SW swell. 
.THU...E wind 15 kt. Seas 6 ft. SW swell in the morning. 
.THU NIGHT...NE wind 10 kt. Seas 5 ft. 
.FRI...E wind 15 kt. Seas 5 ft. 
.SAT...E wind 15 kt. Seas 7 ft. 
.SUN...NE wind 20 kt. Seas 8 ft. 

$$

747 
FZAK53 PAJK 040055
CWFYAK

Marine Forecast for Yakutat Bay
National Weather Service Juneau AK
355 PM AKST Wed Mar 3 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.

PKZ053-041900-
Yakutat Bay-
355 PM AKST Wed Mar 3 2021

.TONIGHT...NE wind 15 kt. Seas 7 ft. SW swell. 
.THU...E wind 15 kt. Seas 5 ft. SW swell in the morning. 
.THU NIGHT...NE wind 15 kt. Seas 4 ft. 
.FRI...E wind 15 kt. Seas 4 ft. SW swell. 
.FRI NIGHT...E wind 10 kt. Seas 6 ft. SW swell. 
.SAT...E wind 15 kt. Seas 7 ft. 
.SUN...NE wind 20 kt. Seas 8 ft. 
.MON...NE wind 10 kt becoming light. Seas 4 ft. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
235 PM AKST Tue Mar 2 2021

.SHORT TERM...Convective showery activity has been continuing
throughout the Panhandle today due to the southwesterly onshore
flow that we have been experiencing for a couple of days. That
will continue into tonight. A low will emerge into the Gulf from
the south tomorrow morning. A wave will ride up the Panhandle to
the east of the low around its circulation Wednesday into
Wednesday night. That will bring some more precipitation to the
area. Generally, precipitation looks to be primarily of the wintry
mix / rain category at the surface for the majority of the
Panhandle due to surface temperatures being in the middle to upper
30s on average for the majority of areas. Of course, the
exceptions are the Klondike and Haines Highways cold spots.

The chance of thunderstorms that that is currently in the forecast
will continue through tonight with the onshore flow along the
outer coast due to conditionally unstable model forecast lapse
rates and marginally negative lifted indices. The onshore flow
will cease tomorrow morning as the aforementioned low lifts
northward into the Gulf and its wave moves up toward the southern
and central Panhandle.

Model forecast 850 mb temperatures will be around -5 to -9 on
average throughout the short-term forecast period with lower
values in the extreme northern Panhandle near Haines and Skagway.
That is cold enough for snow everywhere in the Panhandle in the
upper levels, but guidance suggests that the surface temperatures
will remain too warm for any significant accumulation throughout
the period. Generally, most areas will see a wintry mix through
the forecast period if they get precipitation as overall
southerly flow continues throughout the timeframe for most areas
in Southeast Alaska as subsequent lows approach and influence the
area. Additionally, model forecast thickness values are generally
borderline for snow throughout the Panhandle through the period.
Showers will taper off from northwest to southeast until the next
system approaches southeast Alaska starting Thursday evening.
Stratiform precipitation will spread into the southern and
central Panhandle from the south as that next system approaches
the southern Panhandle.

This new low looks to approach the Panhandle from the south for
the Thursday evening through Friday night timeframe. Model
agreement on the exact track and intensity of this low is not very
good, yet. The GFS has it getting the deepest getting the
pressure down to 988 mb, but tracking it up along the outer coast
of the Panhandle and coming ashore around Port Alexander Friday
morning. The EC has a similar track, slightly farther east, but
less intense. The Canadian & NAM have the low less strong and
moving up between Graham Island and the British Columbia mainland,
making landfall over west-central British Columbia on Friday
night. Therefore, based on this information, I went with an
EC/GFS/Canadian/NAM blend for that timeframe to get an average
location and strength of that system.

I had to drop the surface temperatures over the extreme northern
and western Panhandle Thursday evening into Friday due to cold
air advection moving in from the Canadian Yukon with the flow
around the low around the southern Panhandle and the high over
northwestern Canada. This is indicated well at 850 mb. Luckily,
the northern Panhandle will remain dry during this part of the
short-term forecast period as those areas dip into the lower to
middle 20s.

.LONG TERM.../Thursday through Tuesday night/...The message today
remains mostly the same as yesterday, as the active pattern
continues throughout the long term with a possibility of a precip
break Sunday into Monday. Temperatures do not appear to warm or
cool substantially during the long term and will hang close enough
to freezing to make snow a consideration in at least some portion
of the forecast area with each passing disturbance.

Models continue to be in good agreement Thursday with a digging
upper level trough over the gulf. At the surface, models are also
in decent agreement with a broad low in the gulf, and
disturbances rotating around the system bringing periods of
precipitation and wind to the panhandle, with no signatures of
anything extraordinary. Precipitation type and the timing and
strength of the impulses will be the forecast challenges as the
long term drifts into the near term, and will continue to be
refined.

The long term forecast begins with leftover showers mainly over
the central and southern panhandle on Thursday from one of the
impulses. Deterministic models and the ensembles backed off on
the strength of the surface low approaching the panhandle from the
southeast and riding up the coast throughout the day on Friday,
and instead have it being a weak precursor to the next front
approaching the coast on Saturday. This front looks more robust
than yesterday, and due to the run-to-run differences, the
forecast package contains a middle of the road blend. Sunday and
Monday still look to be the best chance for a break from the
active weather but confidence is low for the extended period.
Models show another front approaching the coast by Tuesday
morning. A blend of GFS and European were used for the early part
of the long term, with NBM and WPC for the latter part of the long
term.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind until 3 PM AKST this afternoon for AKZ018.
MARINE...Small Craft Advisory for PKZ012-022-031-036-041>043-051>053.

&&

JLC/BFL

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