Small Craft Advisory 314, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
251 PM AKDT Fri Jun 2 2017

.SYNOPSIS...An upper level low will persist over the E gulf
through the Saturday before lifting N and weakening to a trof as
an other upper low moving into the far SW gulf Sunday. Minor
perturbations rotating around the parent low will maintain the
active weather pattern through next.

&&

.SHORT TERM.../Friday night through Sunday afternoon/...The
current satellite imagery shows the forecast areas under cloudy
skies with a band of showers over the southern half of the area.
This band will slowly lift north through this evening and the
showers will spread northward tonight. The southern areas will
continue to see showers move over the area into Saturday with them
being closer to the surface low pressure over the Southeast gulf.
The northern areas will see the showers decrease through Saturday
morning with increasing offshore flow but there may be a shower
or 2 that will move over the mountains in the late afternoon. The
winds over the southern third area a on the gusty side at this
time but they will decrease as the band of showers moved north
this evening. There will be another increase from the southeast
as a stronger surface trof rotates over POW through Saturday.
Winds will be from the southeast and range from 10 to 20 mph with
some higher gusts. The surface low will remain over the southeast
gulf so there will be a higher threat of precip for the southern
half with stronger onshore flow and significant upper level
dynamics. The northern half will be drier with again more offshore
flow and diffluence aloft on Sunday. There may be some breaks in
the cloud cover come Saturday evening over the northern third with
the offshore flow and subsidence.

.LONG TERM.../Sunday through Friday as of 9 pm Thursday/ Large
scale upper trof will persist over the E PAC and Gulf of AK
through next week. There will be several systems that affect the
area through that time. Models take sfc low over the SE gulf
Sun morning and move it NW then W through the S gulf while
weakening to a trof by Sun night. An occluded front should move NE
into the SE gulf by Mon afternoon, then turn more NW and weaken
over the gulf Mon night and Tue. Parent low of the front should
move into the SW gulf by midweek, and it will likely send one or
more low pressure trofs into the E gulf during mid to late week.
All these systems will keep mostly wet weather over the area
during the long range period, but there will likely be breaks in
the precip as well between systems. Kept the Sun-Sun night
forecast pretty much as is, then went with new WPC for Mon onward.

&&

.MARINE...Small craft winds will persist over the southeast gulf
through Friday evening with at least 25 kt or 8 ft seas. The
winds will decrease to less than 20 kt from the southeast into
Saturday but as the surface low moves into the far southeast gulf
another band of 25 kt will move over the area. Further north winds
will be on the lighter side. Over the inner channels small craft
winds will persist over Clarence strait this evening but also
decrease late tonight. There is an increase in east winds near
Cross sound witch is near small craft at this time but we do not
expect them to last long. The rest of the inner channels will see
an increase in S winds 10 to 15kt this evening but then with a
light pressure gradient the winds will be on the lighter side
generally less than 10 kt. These conditions will continue for the
inner channels through Sunday with some minor increases in speed
along with changes in direction from N to S from morning to
afternoon and from evening to overnight time frames.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ036-041>043-051.

&&

ABJ/RWT

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