Winter Storm Watch 19, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
347 PM AKST Wed Dec 29 2021

.SHORT TERM.../Wednesday Night through Thursday Night/...A quick
moving area of low pressure brought snow, rain, and areas of a
wintry mix (including some areas of freezing drizzle) to the
panhandle today. Snow accumulations were generally in the 1-3 inch
range, with some areas seeing that amount in just a few hours
during the period of best moisture and dynamics. Gusty winds and
direction changes were also observed at various locations as the
system moved through. Satellite and webcams are showing clearing
behind the storm and the panhandle is expected to clear out from
north to south through this evening, with mostly clear skies
expected tonight. A Winter Weather Advisory is in effect for the
Petersburg/Wrangell area through the evening as the back edge of
the snow is expected go through shortly. Small craft northerlies
are expected to develop this evening in Lynn Canal responding to
the northerly pressure gradient as the low moves to the south.

Thursday will be a cool, mostly clear, calm weather day across
the panhandle ahead of the next storm approaching for the New
Year's holiday - see the long term discussion for details.

.LONG TERM.../Friday through Monday/ Low pressure moves into the
NE Gulf with associated gale force front reaching the Eastern
Gulf Friday morning. Initial cold temperatures will have precip
start as all snow. As the front moves inland heaviest snow fall
rates will occur Friday night, which will make evening festivity
travel an issue. Saturday afternoon the low will track south along
the panhandle coast the linger in the SE Gulf Sunday. High
pressure builds for next week with increased winds and cold
temps.

Snow and Rain: Expecting a warm up starting Friday with temps
continuing to increase overnight and into Saturday. While
precip is initially snow, do have snow levels beginning to rise,
especially for the coastal and southern areas by Saturday. QPF
amounts were backed off a bit by operational models now having the
low shift more to the south and the front tracking in a bit
slower. Except for the southern panhandle which will get heavy
precip amounts on Saturday as the low moves into the SE Gulf. Snow
amounts still very high with this front, mainly due to high QPF
and high snow ratios to start, before the warm up. Northern and
Central areas total snow through Saturday around 6 to 16 inches.
Coastal areas 4 to 9 inches, and Southern regions 8 to 15 inches.
Hyder, as always, will be the expected winner with upwards of 20
to 26 inches.

Latest models runs began to shift the low and front on Friday,
both slowing it down and moving it bit further to the south. NBM
24 hour snow probabilities were still on track for 8+ inches of
snow on Friday but definitely backed off on snow totals Saturday,
mainly due to better consensus on warmer temps. Ensembles snow
totals for both Fri and Sat top amounts were still in the 10+ inch
range. MOS guidance for northern and central locations were still
indicating Fri 8+ inches with lesser amounts Saturday, with
Coastal areas now less certain on Friday amounts. Ketchikan was
most uncertain with NAM keeping 8+ while GFS was half of that.

For the end of the weekend and into next week still lingering
precip for the south on Sunday until the low drops towards Haida
Gwaii. This, along with building high pressure over the Yukon will
result in strong northerly and outflow winds. The amplified wave
pattern over AK will bring in frigid arctic air. Near record
breaking cold temperatures expected.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory until 6 PM AKST this evening for AKZ026.
MARINE...Gale Warning for PKZ041>043-051-052-310.
     Small Craft Advisory for PKZ012-013-022-031-034-035-053.

&&

BFL/PRB

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