Small Craft Advisory 654, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
223 PM AKST Sat Dec 23 2017

.SHORT TERM.../Saturday through Monday as of 2 PM Saturday/ Clear
skies and light winds will continue through Sunday over the
Panhandle. A nearly stationary front is slowly tracking northeast
over the gulf, while an upper level ridge over the Panhandle
slowly breaks down through Sunday. First chances of precipitation
associated with the front will be during the early afternoon hours
Sunday for eastern Prince of Wales Island and spread northeast
through the evening. However, the front will shear apart as it
approaches the Panhandle, which will limit the extent of the
precipitation over the Panhandle. Precipitation will primarily
fall as snow; however, no considerable accumulations are expected.

A weak low pressure system will form near Haida Gwaii along the
front tomorrow afternoon. This will locally enhance winds and
precipitation. The low's southeast track remains of minimal
influence on anything but southernmost Panhandle. Behind this
system a weak surface ridge of high pressure will build over the
Panhandle.

Not many significant changes were made to the short term forecast.
Temperatures were cooled to better represent the persistence of
the pattern the Panhandle has experienced the past few days. POPs
were nudged upward over the far southern Panhandle late Sunday
associated with the low passing over Haida Gwaii. Primary guidance
was the 12Z GFS. Overall forecast confidence is average.

.LONG TERM.../ Monday to Saturday / As of 10pm Friday...The old
blocking ridge has closed off to a high over the Arctic near the
McKenzie Delta, and new small ridge is trying to build over the
Gulf of Alaska on Tuesday but this attempt will get squeezed out
by low in the North Pacific and a trough dropping south from
western Canada. The little gulf ridge survives through mid week
and looks to be pushed through the panhandle by the end of the
week.

At the surface the stalled frontal band that is strung out across
the gulf will be weakening and drifting northward into the
panhandle Tuesday as it dissipates. When it does, general high
pressure sits over the northeastern gulf and into northwest
Canada. As the front dies across the panhandle through Tuesday
night look for 20-30 percent chance of light snow/rain in the
panhandle, then going dry Wednesday and most of Thursday. More
precipitation may be spreading north headed into next weekend.

Pressure and wind wise, the ECMWF/GFS blend was favored to
roughly 06z Tuesday and then a transition to WPC solutions. As a
result this brought up winds through the Lynn Canal region around
mid week. Long range solutions also hinting at warm frontal
feature making a northward trek starting around next
Friday/Saturday across the gulf and southern panhandle.

Overall temperatures have cooled slightly and they may be taking
another minor dip Wednesday to Friday as the east to northeasterly
surface winds pull in some cooler temperatures from Canada. So
temperatures lower 3 to 8 degrees roughly at the end of the week.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Gale Warning for PKZ041.
     Small Craft Advisory for PKZ022-042-043-051-052.
     Small Craft Advisory due to Seas for PKZ053.

&&

JB/Bezenek

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