Small Craft Advisory 129, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
345 PM AKST Fri Mar 3 2017

.SHORT TERM...The low center that caused the snow yesterday
remains over the eastern gulf west of Sitka as of this afternoon.
Another low center developed last night along a wave and is
currently over the POW/Ketchikan region. This feature caused heavy
snow showers for the southern panhandle this morning along with
wind gusts of 30-40mph reported in Ketchikan. Criteria for a
blizzard is for these conditions to occur for at least 3hrs, and
this one came darn close this morning. Snow showers linger down
there into tomorrow morning, but the low has weakened and the
showers have larger breaks in between. Could see around 1-3 inches
down there tonight, but amounts will be highly variable.

For the northern panhandle, offshore flow has taken over with
N-NELY outflow winds of 40-50mph reported in many locations. These
conditions will continue overnight. The outflow winds will ease
some through Saturday afternoon as the low centers drift away
south and cause the pressure packing to subside.

The north wind is bringing in colder air from Canada and clearing
skies tonight will make for temps to be a few degrees colder
tomorrow morning, especially for wind sheltered locations. Windy
spots will be warmer, but still in the 20s. March sunshine will
allow for temps to rebound tomorrow, but not expecting many places
to break the freezing mark.

Used mainly the ECMWF and GFS along with some Canadian models for
certain elements. The 12z ECMWF initialized the low center near
POW Island the best this morning. Forecast confidence is above
average.

.LONG TERM...A strong upper trough has settled over the panhandle
and will remain in place through at least late week. Very cold
air accompanies this trough with 850 mb temps easily down into
the negative teens C across most of the area through at least mid
next week.

Outflow winds and cold temperatures will be the main rule of the
forecast for the next week. The usual outflow areas are expected
to be gusty for several days with gale force winds for Lynn
Canal, and Taku Inlet expected. 25 to 30 kt winds are likely for
many of the other inner channels as well. For land areas expect
gusts to 40 mph or more for Skagway, downtown Juneau and Douglas
(Taku wind event), the passes east of Yakutat for the same time
period and other outflow areas across the northern panhandle.

Temperature will also be rather cold with highs in the mid 20s to
low 30s and lows in the teens and low 20s for many areas. This
will be especially true for wind sheltered areas with clear skies
where radiational cooling at night will see temps drop rather
quickly. The combo of cold temperatures and high winds will also
cause a prolonged period of freezing spray for many of the inner
channels with the possibility of heavy freezing spray likely for
some northern inner channel areas.

The coldest push of air is expected Sun into Mon as a short wave
drops south along the windward side of the main upper trough.
Expect the strongest winds and coldest temperatures Sun night into
Tue as the cold air flowing over the mountain passes intensifies.
Increased outflow winds and lowered temps at that time to account
for this.

Overall good model agreement for the extended period. Changes
mainly focused on outflow winds and cold temperatures through mid
next week.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind through Saturday morning for AKZ025.
     Strong Wind until 9 PM AKST this evening for AKZ017-022.
     Strong Wind through late tonight for AKZ018-019.
     Wind Chill Advisory from 11 PM this evening to noon AKST
     Saturday for AKZ018.
MARINE...Heavy Freezing Spray Warning for PKZ051.
     Heavy Freezing Spray Warning for PKZ011.
     Heavy Freezing Spray Warning for PKZ013.
     Heavy Freezing Spray Warning for PKZ012.
     Gale Warning for PKZ012-013-022-031-034-043-051.
     Small Craft Advisory for PKZ011-021-032-033-035-036-041-042-052-
     053.
&&

Ferrin/EAL

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