Small Craft Advisory 26, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
438 PM AKST Sat Jan 14 2017

.SHORT TERM...Tail end of the front and weather system exits
through southeast Alaska this afternoon. Very strong south winds
from Skagway through White Pass today so extended the Winter
Storm to the afternoon, and then needed to go with High wind for
the Skagway area after it started to gust to 60 to 65 mph in the
morning. The other action packed spot was Misty Fjords where a
foot of snow fell since Friday morning. The snow will likely
continue overnight before mixing with rain by morning.

For Southeast Alaska late Saturday night and early Sunday is the
chance to prepare for the next incoming weather system. Conditions
will worsen quickly in the afternoon hours, while the frontal band
approaches the southeast panhandle. The parent low deepening to
the mid 960s by Sunday afternoon will be moving northward to be
about 200 nm east of Kodiak Island Sunday afternoon. Strong gales
to storm force winds along the front will move into the eastern
half of the gulf in the afternoon. Across the inner channels winds
increasing to small craft to gales.. while the western capes and
cities will start to see increasing gusty winds.

Model agreement was fairly good through Sunday on low track and
increase of rains back across the area.

.LONG TERM...Southeast Alaska will see yet more wind and rain and
of course...snow and wind at higher elevations with more blizzard
conditions ahead. The initial warm front moves north across the
Panhandle Sunday evening. Another short-wave will lift northward
behind the system, effectively training moisture across the
Panhandle into Monday. Thus rain will be heavy at times all across
Southeast starting Sunday night before rates diminish Monday
night. As the current system dropped widespread 24 hour rainfall
totals of 1.5 to 3 inches, the new system may be under-forecast
with 1 to 2 inches now expected Sunday night into Monday. Of
greater impact is the heavy snow for White Pass. Snow will
intensify Sunday evening. By Monday afternoon confidence is high
that over a foot of snow will fall. This leads us to a high
potential blizzard for Monday afternoon/Monday night.

While strong gusty winds of 40 to 55 mph will blow across much of
the Panhandle with Yakutat even shifting directions to a westerly
by Monday afternoon, we are most concerned with Skagway and the
Klondike Highway as the low jumps inland Monday. Winds will
accelerate as this happens much like they did today. Thus we think
high winds to around 60 mph are likely enough to issue a watch. As
Summit Creek observation site in Canada showed us today, and
given periodic AKDOT on the ground reports of conditions at White
Pass, we also feel confident that blizzard conditions will develop
Monday into Monday night. To cover the collection of elements
forecast for Sunday night through Monday night, we have issued a
Winter Storm Warning for White Pass for the entire time period
from Sunday night into Monday night. Even as snow rates diminish
Monday night, blizzard conditions will persist into Monday night.
For Skagway, we have issued a High Wind Watch for Monday into
Monday evening for gusts around 60 mph possible.

In other amendments we greatly raised temperatures in such a
southerly wind regime for the Haines Highway to eliminate
significant snow accumulations. In fact, we do not think a
snowless couple of days is completely out of the question. Still
we do occasionally have some snow mixing in.

A cold front will briskly move west across the northern gulf
Monday and will affect Yakutat with a stark westerly wind shift
with gusty winds from the gulf. While confidence was not high
enough to put out a high wind watch, there is the potential
Monday for wind gusts to reach 60 mph given strong cold air
advection. We raised Yakutat Bay to 40 kt gales during this time.

Long range forecast was left static, but Tuesday, GFS wants to
push a significant low up our coast. Ensembles identify this
period as one of lesser confidence with most members offering a
solution that places said storm well to the south of Dixon
Entrance. Thus, we must state that our wind, our temperatures,
and rain/snow line forecasts look fragile during this time. We
continue to await a clearer signal before we have the confidence
to change things, if needed at all. Winds could be stronger across
the southern and central Panhandle, and rain/snow line could be
pushed northward.

A cooling and drying trend continues to look good for late next
week. EC/GFS was used for Sunday night/Monday night edits.
Confidence falls after this.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind Sunday afternoon for AKZ022-023-025>028.
     Winter Storm Warning until 6 AM AKST Sunday for AKZ029.
     Winter Storm Warning from 6 PM Sunday to 6 AM AKST Tuesday for
     AKZ018.
     Strong Wind from 3 AM AKST Sunday through Sunday morning for
     AKZ018.
     High Wind Watch from Monday morning through Monday evening for
     AKZ018.
MARINE...Gale Warning for PKZ012-021-022-031-033-035-036-041>043-051-052.
     Small Craft Advisory for PKZ011-013-032-034-053.
&&

Bezenek/JWA

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