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FXAK67 PAJK 271449 CCA

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
506 AM AKDT Sun May 27 2018

.SHORT TERM.../Sunday through Monday night/...A gale force low is
situated over the north-central Gulf of Alaska and will remain
quasi-stationary through the day Sunday. It will then begin to
drift east-southeast Sunday night and eventually reach the
southern outer coast late Monday night. A fast moving short wave
which has developed along an old frontal boundary will cross over
Haida Gwaii later today and continue moving northeast into Canada
Sunday night. Showers continue to rotate around the Gulf low and
heavy rain associated with the short wave will spread over the
southern panhandle. A very wet remainder of the Memorial Day
Weekend seems unavoidable.

Gale force winds over the Gulf will slowly but steadily diminish
as the low weakens. Likewise small craft winds on the inside. By
Monday afternoon, the weakening low will get close enough to the
southern outer coast to produce small craft winds over Clarence
Strait, but these winds will diminish back down to 20 kt or less
Monday night.

The low over the Gulf has gone barotropic and as a result, there
is no meaningful temperature advection associated with it. Low
level warm air advection associated with the fast moving short
wave will remain south of the Panhandle. Net result will be very
little diurnal temperature spread. Highs today and Monday will
range from the upper 40s to the lower 50s. Overnight lows will be
in the low to mid 40s.

Model agreement in the short range was better than average and
little change to the existing forecast was necessary. Made a
slight increase to PoPs for Sunday night. GFS used to nudge
temperatures. Winds over the Gulf were updated using NAM. Overall
forecast confidence is above average.

.LONG TERM.../Tuesday through Saturday as of 10 PM Saturday/
Tuesday will see the beginning of a drying trend over the
Panhandle. The remnants of a low will dissipate over the Southern
Panhandle on Tuesday. Any showers that remain should dissipate
during the afternoon hours, as a ridge of high pressure begins to
build over the gulf and Panhandle. This ridge looks to stay in
place until next weekend. Light winds or sea breezes will likely
dominate the middle of the week associated with the ridge. More
seasonable temperatures return as well as highs range from the
upper 50s to the low 60s during the middle of the week.

Toward the weekend, the ridge begins to break down and a surface
low pressure system develops. Current ensembles are keeping the
low south of Panhandle, which would limit its impacts to SE AK.
However, run to run consistency has been poor with this system,
and ensemble spreads are large, leading to below average
confidence as the weekend transpires.

One other concern in the long term is fog formation Tuesday night
through Wednesday morning. With light winds, clearing skies, and
abundant surface moisture from numerous days of rainfall,
favorable fog formation conditions will be present over much of

Overall not many significant changes to the long term forecast
were made. We did nudge the weekend forecast toward newest
guidance from WPC, after coordinating with our partner office in
Anchorage; however, confidence remains low in that timeframe with
a larger change expected in the long term forecast as models
obtain a better handle on the low.


.AVIATION...Wind shear has for the most part ended except for the
northeast Gulf coast, but conditions there will improve by late
this afternoon. VMC will generally prevail with some areas of
MVMC. Expect some turbulence below ridgetops over the northern
panhandle until the gale in the Gulf weakens below small craft
intensity. Conditions very slowly improving through Monday night.


.AJK Watches/Warnings/Advisories...
MARINE...Gale Warning for PKZ043-051.
     Small Craft Advisory for PKZ012-013-021-022-031-032-034-041-042-
     Small Craft Advisory due to Seas for PKZ053.




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