Small Craft Advisory 263, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
327 PM AKDT Tue May 2 2017

.SYNOPSIS...A storm force low has moved into the central gulf. Gale to storm
force winds will effect the eastern gulf into Wed along with high
seas. The front associated with the low has begun to pass over the
southern panhandle. The low will drift northwest Wed where it will
slowly weaken.

&&

.SHORT TERM.../Tuesday night through Thursday/ The primary concern
currently is the storm force low that has begun to affect
southeast Alaska.

The front associated with the low has begun to pass over the
southern panhandle. As the front moves northward rain will
increase over the entire panhandle. Rain may be heavy at times,
with the heaviest rains this evening before turning to showers.
Showers will continue into tomorrow afternoon over much of the
panhandle, where the chances of the showers will begin to
diminish over the southern panhandle first and slowly bring
diminishing chances of rain northward into Thursday.

In addition to the rain, strong winds will effect much of the
panhandle as the low moves northward. Strongest winds are expected
along the outer coast from Prince of Wales Island to Cross Sound
and over the southern inner channels, where wind gusts up to 50
mph are expected. The strongest winds will pass this evening then
slowly diminish through the overnight hours. Winds will be
strongest late Tuesday night into early Wednesday morning for much
of the northern panhandle. There will be some places that will see
strong winds gusts over the inner channels through Wednesday as a
ridge builds over the area behind the front.

Models are in good agreement in the short term, with the NAM being
used for primary guidance and some high resolution input for
winds and precipitation.

.LONG TERM.../Thu through Tue night/ Overall upper level pattern
becoming more transient into next weekend as the upper trough
that was nearly stationary earlier this week starts to get pushed
east. The features that replace it do not stick around all that
long, but there is a trend that they will move through slower then
what was depicted yesterday. The main features of note are a
ridge moving through over the weekend followed by a new trough
settling into the gulf early next week.

At lower levels, the strong low from earlier in the week will be
on its last legs. Lingering rain showers will be plaguing the
northern panhandle and the gulf through at least Thu night before
the advancing ridge gradually shuts them off. Winds will also be
on the diminishing trend with 25 to 30 kt winds in the gulf Thu
lowering to less then 20 kt by late Thu night.

Fri into the weekend still looking like it might be dry for most
areas. Though the question remains on how much cloud cover will be
around. The dominate NW flow suggests that clouds will still
linger especially in the gulf and along the outer coast so left
mostly cloudy skies in for most areas. The next front incoming for
the late weekend and early next week still suffers from timing
issues from the various models. Current trends have slowed the
front enough that it does not reach the panhandle until late
Sunday night now. Mainly favored WPC for long range guidance.

&&

.AVIATION...The front that is moving over the forecast area this evening will
produce some strong low level wind shear ranging from 40 to 50 kt
near the thousand foot level from the southeast. Along with the
wind shear there are strong land winds but as the front moves through
the area a wind shift will occur after midnight. The heavy rain
will lower ceiling and visibilities at times tonight but as
showers move over the area behind the front air fields will some
improvement from mvfr conditions late tonight.

&&

.MARINE...Sea travel will continue to be hazardous with this storm
force low. Seas in excess of 20 ft for the gulf are expected. In
addition as the low moves northward winds over the inner channels
will build to small craft and gale force levels.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind from 7 PM to 10 PM AKDT this evening for AKZ021-026.
     Strong Wind until 1 AM AKDT Wednesday for AKZ027.
     Strong Wind from 7 PM AKDT this evening through late tonight for
     AKZ017-025.
     Strong Wind through late tonight for AKZ022.
     Strong Wind until 1 AM AKDT Wednesday for AKZ023-028.
     Strong Wind late tonight for AKZ018-019.
MARINE...Storm Warning for PKZ042-043-051-052.
     Gale Warning for PKZ022-036-041.
     Small Craft Advisory for PKZ012-013-021-031>035-053.

&&

Byrd/EAL

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