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FXAK67 PAJK 191509

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
609 AM AKST Fri Jan 19 2018

.SHORT TERM... A low to the south of Haida Gwaii will move
northwest through late tonight into the Southeast gulf. This
should bring some rain and snow showers further northward into the
panhandle. Another low is tracking to the west along 50 N which
will pull the first low to the southeast Gulf.

New model runs have not changed the trajectory much for the
dissipating low over the southern panhandle, but seem to be more
consistent in defining the low. Some minor changes to pressure
were made using a NAM/EC blend and winds increased slightly using
the NAM with the passage of the low, with small craft advisories
remaining in the outer coast and Northern Lynn increasing to gale
force by tomorrow night.

A NAM/SREF blend was used for POP, backing off some of the
precipitation over the panhandle for tonight and brining it back
in tomorrow. There will be quick changeovers from rain to snow
tonight, as a band of WAA squeezes in ahead the low. Again, there
is the potential for some patchy fog to develop tonight in
Petersburg, Ketchikan, and Metlakatla.

While there is a decreasing trend in temperatures for the short-
term period, both maximum and minimum temps had to be increased
slightly to be within the model spectrum spreads. The GFS wanted
to remain slightly warmer, as this could affect the rain/snow
transitions into tonight. The CPC outlook for the next 10 days
shows precipitation and temperatures to remain slightly below
normal. Forecast confidence remains average to above average with
good continuity in the pattern over the next several days.

.LONG TERM.../Sunday through Friday as of 10 pm Thursday/
Models in a little better agreement on the larger scale features
through early next week. Upper trof will dig S into the W gulf
over the weekend then base of the upper trof will shift E into the
central gulf early next week as another shortwave digs S into the
W side of the upper trof. After Tue however, the models differ on
where the various shortwaves within the trof go. Does appear that
the mean trof axis will reform further W late in the week however.
Blended in latest WPC for most parameters starting 12z Mon. Left
most parameters alone for Sun.

Did warm temps some especially Sun-Tue. Initial colder airmass
coming in from the N will stay over the far N area. Colder air
will slowly wrap around sfc low over the central gulf into the
area early next week, but this cool down will be slower. Later in
the week, as upper trof reforms to the W, the cooling trend will
likely end and some moderation in temps is likely by late week.

Did keep in likely POPs over much of the central and S area early
next week as a couple of systems move in from the SW. Some
decrease in POP is possible for latter part of the week as main
low level flow may become more offshore, but still a lot of model
differences to resolve that far out.

Looking like the most wind will be with any lows over the gulf.
There may be some outflow as well over the N third of the area,
but it does not look particularly strong due to lack of a
strong sfc high over the Yukon. However, any stronger lows that
would move into the E gulf could increase outflow more than
current forecast has it.


.AJK Watches/Warnings/Advisories...
MARINE...Small Craft Advisory for PKZ012.
     Small Craft Advisory due to Seas for PKZ041>043-051-052.




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