Heavy Snow in Alaska, December 22 to 24, 2022

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
654 AM AKST Thu Dec 22 2022

.SHORT TERM...Flurries across much of the panhandle through the
day on Thursday ahead of a strong advancing system which will
bring with it significant snowfall across most of the panhandle.
Strong northerly winds remain across much of the area through the
time frame, and outflow conditions will largely remain through
Thursday, with the exceptions of the S panhandle, where the
advancing system will result in a changing wind regime. Snow will
spread from S to N Thursday evening onwards. Initially, dry air may
act as an impediment to the snow, but the advancing frontal band
will be able to overcome it. The potential for high snow ratios does
exist, particularly early on in the system, which could result in
higher or lower snow amounts initially depending on location.
Anticipate gale force and small craft wind conditions across much of
the area through the time period, with storm force winds in the Gulf
of Alaska Thursday morning.

.LONG TERM.../Friday through Monday/...Very active pattern and
complicated for the weekend and early next week with increasing
temperatures and significant precipitation from three separate
systems. By the weekend, the southern panhandle will see
temperatures into the low to mid 40s while the rest of the
panhandle will see upper 20s and low 30s.

Beginning Friday at Midnight, snow will kick off the wet pattern
in the southern panhandle from a frontal band from a developed low
in the gulf. From the entrenched cold air mass already in pace
from the previous cold air outflow event and easterly flow during
the event, significant overrunning is expected with total
accumulations between 8-12 inches. Precip will move up and impact
the mid to upper panhandle later in the day. Optimal lift in the
dendrite zone for the southern panhandle along with lift appears
to occur in the overnight hours, which is likely where the
heaviest snowfall will happen. The GEFS, CMC, and deterministic
GFS all agree on the track of the first low and frontal band.
Overall confidence regarding the first system is high.

Moving into Saturday, Precipitation will hand around the southern
panhandle while the central and northern Panhandle will likely experience
a brief lull in snow before a second band of precipitation from
the second low moving into the gulf. Again, much like the
previous, a frontal band is expected to move up over the entire
panhandle around Saturday morning. By this time, warm air mixing
is expected to transition snow to rain in the southern panhandle
but stronger, northerly winds in the north and central panhandle
will likely keep precipitation type as snow for the inner channel
areas.

For Sunday, expect to see heavy rain for the S Panhandle. Further
north, precip will be more of a mix through the central panhandle
and along the Icy Strait corridor while the N Panhandle looks to
see straight snow during this time. With some of heavy precip
moving into the central panhandle, accumulation amounts look to be
higher for areas that receive more precip. But there is still
some uncertainty with regards to timing and amounts during this
time. Along the Gulf coast, precip will be either a mix of rain
and snow or straight rain before turning to rain. Winds during the
day on Sunday will ramp up across the S Panhandle with the
potential of reaching gale force for many locations on the water.
Farther north, winds will be in the twenty to thirty knots range
depending on location. Locations in the north that look to be on
the higher end at this time are those that tend to be favored by
cold air outflow. For the start of the week, winds look to
decrease below gale force but still have the potential to be
breezy.

After Sunday, temperatures continue to trend upwards to be above
normal for this time of the year going into next week. Along with
these warmer temperatures, we will see an increase in precipitation
for the region as well during this time. As for the trend for the
rest of the year, current outlooks continue to paint a picture of
above normal temperatures and leaning towards an above normal
precipitation as well.

&&

.AVIATION...Overcast high clouds will gradually lower through the
day. Some flurries are possible, then light snow will steadily
increase from south to north this evening. Expect conditions to
lower quickly to MVFR as snow begins, then to IFR shortly after.
Gusty winds will continue out of passes to the east.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Wind Chill Advisory until 6 AM AKST Friday for AKZ318.
     Winter Storm Watch from late Friday night through Saturday
     afternoon for AKZ318-319.
     Winter Storm Warning from 3 PM Friday to 3 PM AKST Saturday for
     AKZ320>322-324-325.
     Winter Weather Advisory from midnight tonight to 6 AM AKST
     Saturday for AKZ323.
     Strong Wind from 6 PM AKST this evening through late tonight for
     AKZ325.
     Winter Storm Warning from midnight tonight to 6 AM AKST Saturday
     for AKZ326>332.
MARINE...Gale Warning for PKZ012-013-041>043-053.
     Small Craft Advisory for PKZ021-022-031>036-051-052.

&&

SHORT TERM...GFS
LONG TERM....ABJ
AVIATION...Ferrin

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