Gale Warning 20, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
259 PM AKST Thu Jan 6 2022

.SHORT TERM...Satellite imagery this afternoon showing a
developing low west of the AK gulf, cloud band over the Yukon
moving south, and a low near Haida Gwaii weakening and tracking
to the south. Nearing the end of our frigid arctic outbreak with
strong outflow winds. But just before the end had one of the
coldest nights so far with a few locations (mainly with shorter
data collection time frame) hitting record low temperatures. The
Juneau NWS office reached -18 F this morning. Skagway airport was
the winner on winds gusts with a peak of 64 mph overnight. As the
NW Canadian high pressure weakens and the Haida Gwaii low moves
south pressure gradients will decrease with diminishing winds
through Friday night. However this will be a short lived break due
to strong lows and fronts moving in Saturday (see discussion
below.)

For Friday a weak low forms in the NE Gulf and tracks south along
the panhandle coast eventually merging with wave activity coming
up from the south. Initially all precip from this low is expected
stay off shore Friday with mostly increasing cloud cover, but by
Friday night as it strengthens will have increasing PoP for the
south. Lots of model spread on this system and how far north it
moves in, but this is typical for models dealing with break down
of an extended blocking pattern such as we've had for AK. GFS is
bullish on moving in precip further north and higher QPF. Canadian
does not goes as far north as the GFS but has higher QPF for the
south. ECMWF and NAM keep all precip out of the area until main
front moves in for Saturday. If precip does move in will be be all
snow with a good hit of snow totals due to high snow ratio.
However leaning more toward the 'drier' solution, especially for
the central and northern panhandle. Forecast confidence is below
average due to the large model spread and run to run
inconsistency.

.LONG TERM...(Saturday onwards) A pattern change is expected in
the long term with a rapid warm-up, back-to-back precipitation
events, and strong coastal winds.

A very wet weekend and next week is expected with back-to-back
rounds of subtropical moisture being pushed northwards. Winter
Storm Watches are issued for the entire panhandle Saturday into
Sunday and precipitation will continue through the week. This
first system is a major snow to rain event with warm, moist air
coming from the Souther Pacific. Forecast confidence on the timing
and location of this system is low, which is why the forecast has
a large range of snowfall. Lowest confidence on when the warm air
will arrive for the northern half of the panhandle, especially
Northern Lynn and Juneau areas. Expect lowest temperatures to
occur early Saturday morning and to gradually increase through
the weekend, resulting in near normal temperatures for the
panhandle. Marine winds increase to high-end gales with boundary
jets seeing the highest winds along the Gulf coast, diminishing
on Sunday. Gusty land conditions are expected across the panhandle
with the highest gusts expected near Hydaburg and Ketchikan, with
strong vertical wind shear expected elsewhere, especially Yakutat.
See the Winter Storm Watches and your local forecast for more
details.

Continued to trend precipitation and snowfall amounts upwards and
adjusted the system to move in a bit later to follow the
EC/Canadian guidance, as the GFS is the outlier. Moderated
precipitation at the end of this main system to show a potential
quick break early Monday before a weaker low moves into the Gulf.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Storm Watch from Saturday afternoon through Sunday
     afternoon for AKZ023-024-026>028.
     Winter Storm Watch from Saturday evening through Sunday evening
     for AKZ017>022-025-029.
     Wind Chill Advisory until noon AKST Friday for AKZ018-019.
     High Wind Warning until 6 PM AKST this evening for AKZ018.
MARINE...Heavy Freezing Spray Warning for PKZ011.
     Heavy Freezing Spray Warning for PKZ012-031.
     Heavy Freezing Spray Warning for PKZ013.
     Gale Warning for PKZ012.
     Small Craft Advisory for PKZ013-022-031-032-041>043-051-052.

&&

PRB/KRT

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