High Wind in Alaska, January 8, 2021

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
650 AM AKST Fri Jan 8 2021

.SHORT TERM.../Friday through Saturday night/...A weakening storm
force low that will approach the Panhandle from the south today
and weaken further. It will cause the winds to shift to southerly
across the Panhandle as it approaches and moves inland, today. In
the Lynn Canal region of the northern Panhandle, it could bring
in some warm air off the channel waters and some weak warm air
advection from the south to warm things up in the Haines and
Skagway areas. This weakening warm air advection can be seen in
the models at 850 mb riding up the Panhandle as the weakening low
approaches and moves inland over southeast Alaska. This could
potentially make it up the Haines Highway to the Canadian border
and make the precipitation change over to a mix or rain, lowering
additional snow amounts in the afternoon and overnight, but that
is yet to be seen and it is not guaranteed. This low will bring
precipitation chances to the Panhandle during the break between
the prior system and the strong frontal system that will approach
the area for the Saturday timeframe.

Although short lived, this low looks to bring a plethora of
strong winds, Storm force winds, Gales, and enhanced seas to some
of the southern land and marine zones until the afternoon due to a
tight pressure gradient. A High Wind Warning is in Effect until 1
PM AKST for the Ketchikan, Klawock, Craig, and Hydaburg areas in
the southern inner channels and southwestern Gulf coastal areas of
the Panhandle. A Storm Warning is in effect for Clarence Strait
for high winds and elevated seas.

Another storm force front looks to bring a variety of different
weather impacts to the Panhandle and adjacent waters around the
Saturday timeframe. These include strong impactful winds over land
areas and waters, enhanced seas, and appreciable rainfall
amounts. It could also bring some appreciable snow amounts for the
areas around the roads that cross the Canadian border. Healthy
modeled IVT values indicate that there will be a long fetch of
deep moisture from the central Pacific aimed at the Panhandle. In
other words, plenty of moisture will be available to this system
and the subsequent parade of systems over the next several days.
Along with this, generally onshore flow over the Panhandle, any
enhancement of precipitation via topographic uplift, and the
persistence of systems approaching the area over the next week,
appreciable amounts of rainfall could be observed.

Generally, temperatures should remain near what we have been
experiencing over the past few days across the Panhandle with
temperatures remaining in the 30s and 40s throughout much of the
Panhandle for the short term forecast period. The common
exceptions will be up along the Haines and Klondike Canadian
border crossing highways and around Hyder where temperatures
should, generally, remain in the 20s to 30s range.

According to guidance, we are getting into a very active pattern
with parade of storm systems and waves approaching the Panhandle
over the next week with short breaks.

.LONG TERM.../Sunday through Friday as of 10 PM Thursday/
Mid/upper level wave pattern for the long range stays relatively
unchanged with ridging over western Canada/US and deep trough over
the AK Gulf and out to the Aleutians. What this means is
continuing active weather pattern favoring deep cyclogenesis
emergence into the Gulf of Alaska Sun/Mon whose enhanced onshore
moisture fetch and circulation is expected to fuel a threat of
increased precipitation and high winds/waves. As the week moves on
getting more consensus from ensembles that the active weather
will subside somewhat as the upper wave pattern shifts to the
west, thus keeping low development further to the west of the
region. Standardized anomalies with NAEFS and ENS, while still
above normal, for temperatures, wind, and precipitable water are
much lower than seen the past few days. However even with this
ensemble consensus of overall pattern there is still low
predictability on the developing surface lows. This is even more
evident when looking at operational model runs. Used a blend of
GFS/ECMWF for the Sunday system, then kept with WPC for its
ensemble solution.

For Sunday as the Saturday front moves northward indications of
cyclogenesis along the wave in the western Gulf moving in more
precip and increased winds. Southerly flow for most areas keeping
precip mainly as rain. Area of concern for snow is the far
northern panhandle, which due to overnight northerly flow should have
temps low enough for snow initially. As the low/front tracks
north pressure gradient flips resulting in southerly winds, warm
air advection and a change over from snow to rain. For the start
of the week the frontal band over the panhandle will dissipate,
but beyond that only confidence in saying more lows will
eventually move into the Gulf and region, but might see a shift
toward cooler temps and lower snow levels.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind until 6 PM AKST this evening for AKZ026.
     High Wind Warning until 1 PM AKST this afternoon for AKZ027-028.
     Strong Wind until 7 AM AKST this morning for AKZ027-028.
     Strong Wind from 1 PM this afternoon to 6 PM AKST this evening
     for AKZ027-028.
     Strong Wind late tonight for AKZ027.
     Strong Wind until 9 AM AKST this morning for AKZ023.
     Strong Wind from 3 PM this afternoon to 6 PM AKST this evening
     for AKZ023.
MARINE...Storm Warning for PKZ036.
     Gale Warning for PKZ033-035-041>043.
     Small Craft Advisory for PKZ012-013-022-031-032-034-051>053.

&&

JLC/PRB

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