Wind Chill Advisory 5, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
252 PM AKST Thu Mar 1 2018

.SHORT TERM.../ Through Saturday night / Outflow winds continue to
blow out of and through many of the mountain passes and inner
channels of SE Alaska. Lynn Canal has been blowing storm force
with gusts to hurricane force all day and webcams show clouds of
spray being kicked up by the winds. Ship reports also confirm high
winds (up to 50 kt) and spray blowing out of Dangerous River and
the Alsek River valleys E of Yakutat. Gale force winds extend as
far south as Southern Chatham Strait.

Outflow winds expected to continue through the night before
starting to slowly diminish Friday as the inverted trough over the
SE gulf slowly weakens into the weekend. The strong Yukon high
will stick around, but will shift position (and slightly weaken)
from the southern Yukon to northern BC by Fri night. This shift of
position will start to favor the more NE to SW channels late
tonight. As such, Skagway's, and Taku Inlet's highest winds will
likely be late tonight before the weakening SE gulf trough
diminishes the pressure gradient significantly. Small craft winds
will likely linger in some parts of the inner channels through at
least Sat morning. In other areas, High winds have also been
observed at downtown Juneau and Douglas due to Taku winds. Gusts
to 60 to 65 mph have been noted at South Douglas Boat Harbor and
at the Rock Dump for most of the day. A high wind warning remains
up through 11 pm tonight.

In addition, the cold air accompanying this outflow will
continue to produce plenty of freezing spray through the period. A
heavy freezing spray warning has been issued for northern Lynn
Canal for tonight. The cold air is also expected to produce some
low winds chills at White Pass tonight. A wind chill advisory has
also been posted for that area for late tonight through early
tomorrow for wind chills to 30 below zero.

Forecast changes mainly focused on winds and temperatures due to
the outflow today. Favored the Nam and NamNest for wind updates
for the detail that they provide. Otherwise, Changes were minimal
due to the rather dry and mostly clear forecast for the period.

.LONG TERM.../ Saturday to Thursday as of 9 pm Wednesday / High
pressure over northwest Canada is weakening and shifting to the
east over norther Canada. The weak trough of low pressure extends
north from a low off the Pacific Northwest along the outer coast
of the panhandle towards Prince William Sound. The outflow
pressure gradient that is in place late Friday night will be
weakening so expect the winds to slowly diminish on Saturday. A
low that moved to the western gulf by Saturday morning south of
Kodiak Island will turn and dive southward under the influence of
upper level support. The Gulf of Alaska and the Southeast
panhandle will end up under a weak pressure pattern from Saturday
onward.

A trough aloft will move across the gulf Saturday and Sunday that
will spread in some clouds and low chances of light snow, and
a follow up system will form a weak low in the northern gulf that
will move to the eastern gulf for early next week.

Temperatures especially over the northern part of the panhandle
will be moderating from a slightly cooler than normal pattern
Saturday to a more normal temperature pattern early early next
week. The temperatures should be the coolest Saturday morning
though am not expecting temperatures below zero. Forecast
confidence is average to above average.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...High Wind Warning until 11 PM AKST this evening for AKZ025.
     Strong Wind through late tonight for AKZ018.
     Wind Chill Advisory from 9 PM this evening to 9 AM AKST Friday
     for AKZ018.
MARINE...Heavy Freezing Spray Warning for PKZ012.
     Storm Warning for PKZ012-013-043.
     Gale Warning for PKZ021-022-031>033-042-051.
     Small Craft Advisory for PKZ011-034>036-041-053.

&&

EAL/Bezenek

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