Small Craft Advisory 563, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
311 PM AKDT SUN SEP 11 2016

.SHORT TERM...A strong front will slide east from the central
gulf to the northern panhandle Monday. This will bring a rapid
end to the dry weather occurring from Saturday into today. While
light rain spreads east across the northern panhandle
Monday...rain will become heavy over Yakutat Monday morning.
Southerly winds will rise Monday morning over Yakutat with gusts
to around 30 mph before extending eastward across the northern
Panhandle. A short-wave passing across Lynn Canal region Monday
afternoon will enhance wind speeds through this region to 40 kt
with strong wind gusts of up to 45 mph through Skagway. This will
be a prelude to the potential of a bigger event coming Monday
night.

Fog was dense this morning across most of the panhandle
underneath a surface ridge with light winds. Much of it waited
until mid-day to mix out. With only moderate confidence that cloud
cover will indeed begin to spread across the area tonight to
inhibit radiational cooling, we think fog could redevelop across
the region as early as this evening. Dense fog is certainly
another possibility locally over the south where cloud cover will
be weakest.

.LONG TERM...Active weather pattern through the weekend.

Atmospheric river will be sliding southeast over the panhandle on
Monday evening. This will bring a period of heavy rain to the
northern and central panhandle before eventually reaching the
southern panhandle on Tuesday morning. Gusty winds will accompany
the heavy rain with gusts of 30-40 mph over the central and
northern panhandle Monday and early Tuesday. The strongest winds
will occur over Northern Lynn Canal and Skagway. 700 mb
southwesterly flow increasing to 60 kt will enhance wind at
Skagway on Monday evening and into Tuesday. Based upon latest
guidance, issued a high wind watch for that time frame with gusts
up to 60 mph possible. See the hydrology and marine sections
below for additional information on this storm system.

The remainder of the week will feature multiple fronts crossing
the gulf with brief breaks in the precipitation and wind between
fronts. A typical fall pattern for Southeast Alaska.

Used hi-res guidance at the beginning of the long range then
transitioned to NAM/EC through day 4. Latest WPC guidance was used
thereafter.

&&

.MARINE...As a strong weather front passes across the gulf, we
expect winds of 25 to 35 kt to develop from west to east over
zones 43, 50, and 51 through Monday night. Inside Passage winds
will be generally light tonight with the exception of stiff small
craft southerlies anticipated for northern Lynn Canal. Winds will
increase markedly Monday across the northern Inner Channels with
25 to 30 kt winds spreading throughout the Icy Strait-Juneau areas
northward. Strong gales to 40 kt with 7-8 foot seas are expected
through Northern Lynn Canal from Monday afternoon through Tuesday
morning. Light winds in the south will turn southeasterly and will
strengthen Monday night to 20 to 25 kt. Fog will potentially be a
factor in visibility again tonight into Monday morning...especially
over the south. Rapid evening cooling could help redevelop fog
across the north tonight, but increasing winds will mix the
boundary enough to end fog by the morning. Highest confidence for
fog is across the southern Inner Channels where it may be dense.

&&

.HYDROLOGY...Another atmospheric river will move in from the west
beginning Monday. Rain will begin over Yakutat late tonight.
Strongest lift passes over the northeast gulf mid-morning, likely
causing rain rates of a quarter to a half inch per hour Monday
across Yakutat. The rain tracks eastward over the northern
panhandle Monday night. We think these high rain rates will
result in enough run-off to raise river levels rapidly into
Tuesday morning across the northern panhandle, but no flooding is
anticipated.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...STRONG WIND Monday afternoon for AKZ025.
     High Wind Watch from Monday evening through Tuesday morning for
     AKZ018.
     STRONG WIND from Monday morning through Monday afternoon for
     AKZ018.
MARINE...Gale Warning for PKZ012-013-051-052.
     Small Craft Advisory for PKZ011-021-022-031-032-043-053.
     Small Craft Advisory due to Seas for PKZ042.
&&

JWA/TPS

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