Heavy Snow in Alaska, February 1 to 2, 2023

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
245 PM AKST Wed Feb 1 2023

.SHORT TERM...Satellite imagery this afternoon showing two
systems that will be impacting the AK Panhandle through Friday.
The first is a relatively weak low in the southern gulf that is
now expected to track northward along the Eastern Gulf coast
eventually reaching the NE Gulf where it will have become an open
wave trough. The second is a developing low seen in the NW Pacific
which will move towards Haida Gwaii by Thursday.

The first low is moving in shower activity over the region.
Seeing a mix of snow and rain over central areas, all snow to the
north while the southern areas have been all rain. Should only
seen an inch or two of snow accumulation from these showers but
there is possibility that any stalled cells could product an
additional inch or two. Northerly and outflow winds along with the
fully developed seas over Lynn canal will subside into Thursday
as the gradient weakens and becomes more parallel. The second low
will mainly impact the southern panhandle with increased rain
rates and QPF. Hyder is still on track to get a fair amount of snow
as it will have the increased QPF, like the rest of the south,
but boundary layer temps expected to be low enough for majority
of precip to fall as snow. The rain snow line has been mainly
along the icy strait corridor as reflected by todays temps: upper
30s to low 40s south, low 30s central, and upper 20s to the
north.

Main change to forecast was models picked up on the weak system
tracking north tonight. Had good agreement with GFS, NAM, and
Canadian models. This increased some PoP tonight and the updated
pressure gradient lowered outflow winds slightly. Lower
confidence in snow totals from these cells due to many locations
being just near freezing.

.LONG TERM...An area of low pressure S of Haida Gwaii streams
rain across the S Panhandle Friday and pivots north, allowing for
some precip to fall over the central Panhandle Friday evening. A
general 0.50 to 1 inch of rain is expected across the south with
some light snow showers across the central Panhandle. Saturday,
showers remain in the area for portions of the central and
southern Panhandle. A surface ridge then builds through the
central Gulf Saturday night which will help the northern and
central panhandle stay on the drier side, while the southern
Panhandle will continue to see light rain. Sunday, light showers
stick around the panhandle, but overall, a nicer day for SEAK with
even some breaks in the clouds possible.

Going into next week, a much stronger and more organized surface
low moves into the NW Gulf and brings a front across the
panhandle Sunday night into Monday. Strong gale force winds
between 35 to 45 kts are likely with even 50 kts possible along
the N Gulf Coast associated with the barrier jet. Light to moderate
precipitation moving NW to SE over the Panhandle is also expected
with the front. The system does look to be a fast mover so
precipitation amounts will likely be limited. As for precip type,
this front does look like it could bring measurable snow across
the northern and central Panhandle. Temperatures do look to warm
with the frontal progression, so a change to rain is likely
Monday evening before changing back to snow post frontal with cold
air advection and onshore showers.

Through mid next week, confidence begins to decline as guidance
struggles to resolve a few surface lows over the Gulf, but a
general wet shower pattern looks favorable. By late next week,
ensemble guidance indicates an area of low pressure develops in
the Gulf once again.

&&

.AVIATION...// 00Z TAF ISSUANCE //
As expected, and as the weak low moves north along the eastern
gulf and deeper moisture moves in from the south, satellite
imagery confirms wider-spread precipitation (mostly rain in the
lower levels) overspreading the southern half of the Panhandle
this evening with ceilings/visibilities dropping to MVFR to
occasionally IFR. To the north, scattered snow showers will
continue to spread northward through tonight with periods of MVFR
dropping to IFR. This trend continues into Thursday.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind from Thursday morning through Thursday afternoon for
     AKZ330-332.
     Winter Weather Advisory from 9 PM this evening to 9 PM AKST
     Thursday for AKZ331.
MARINE...Small Craft Advisory for PKZ012-013-031-036-041>043-051.

&&

SHORT TERM...PRB
LONG TERM....CC
AVIATION...JG

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