Heavy Snow in Alaska, December 16 to 17, 2019

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
247 PM AKST Mon Dec 16 2019

.SHORT TERM...Northern portion of Southeast Alaska dealing with
remnants of the frontal system which still had some light snow
falling in the northern inner channels. A more organized band of
showers is offshore the north and northeast gulf coast, and some
of those showers may push into the coast. Across the southern
panhandle a wave is moving northward across Haida Gwaii and
southern panhandle late tonight. We are keeping a close eye on
this track as it could make a difference in the wind forecast for
the Clarence Strait area. A very moist plume of moisture will
move northward over the southern panhandle. Periods of heavy rain
should be expected, however in the Hyder region colder air will
persist and slowly replenished from Canada so Heavy snow is
expected tonight into early Tuesday with around a foot or more
accumulation.

Wrangell and Petersburg could pick up a few inches late
tonight/early Tuesday with 2 to 5 inches possible. With the spread
will not post an advisory for the Wrangell area.

Next frontal band will spread in late Tuesday night and Wednesday
from the Gulf of Alaska. The associated surface low is a
vertically stacked feature that will move east from the Aleutians
so to the southwest-southcentral gulf by Wednesday.

Expect the marine winds to pick up ahead of the Wednesday front,
though it should be limited to small craft levels of 25 to 30 kt.

.LONG TERM.../Wednesday through Monday night/...Extended portion
of the forecast begins with a low spinning in the western Gulf
which will send several waves of energy toward the region from
midweek into the weekend. For the most part, temperature outlooks
seem to remain warm enough to maintain p-type as rain for most
areas at sea level. Exceptions will be for areas at higher
elevations to the north, mostly along our highways leading into
Canada, however could possibly see some snow get into Haines and
Skagway. Yakutat also could see some periods of snow, mainly
during nighttime hours. Further, can not completely rule out some
rain/snow mix at times for central panhandle locations, however
with onshore flow, will be difficult to change over completely,
much less speculate about any accumulations. Hyder likely remains
cold enough on Wednesday to see continued accumulating snowfall,
however temps begin to warm slightly over the course of the week
and any potential accumulation after the initial event ends looks
to be little to none. Exact timing of subsequent rounds of precip
after the initial wave that will be occurring at the beginning of
this period is still pretty uncertain as there is still quite a
bit of discrepancy among various models, however can say with a
good deal of confidence the period looks to generally wet.

As we begin the forecast period, winds along the coast and in the
Gulf will still be moving at near gale with some small pockets
possibly reaching criteria due to a strong pressure gradient
around the low. After Wednesday, winds don't appear to be much of
an issue at this time as the low weakens as it nears the region
before eventually washing out into the overall flow this upcoming
weekend. This will need to continue to be monitored for future
model runs as the actual track of the low could cause some wind
issues, but for now with as much discrepancy between various
runs, will need to see some more consistency before any decent
confidence in this wind forecast can be declared.

By the beginning of next week, another low will be crossing the
Aleutians to begin the repeat after the wash and rinse from this
week.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Winter Storm Warning from 9 PM this evening to noon AKST Tuesday
     for AKZ029.
MARINE...Small Craft Advisory for PKZ022-036-041>043-051>053.

&&

Bezenek/JDR

Visit us at http://www.weather.gov/Juneau