Small Craft Advisory 76, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
545 AM AKST Fri Jan 31 2020

.SHORT TERM...After a powerful low moved through yesterday,
bringing incredibly high winds to some areas (109 mph recorded at
PAKT) and large amounts of snow to others (daily record of 7.3 at
PAJN), we deserve a bit of a breather. As that low continues to
track further into the interior of Canada, our weather in the
panhandle begins to fall more under the influence of another much
weaker low currently in the northwest Gulf. Around this low,
multiple bands of precipitation will be kicked up and pushed into
the region in onshore flow. For northern and central panhandle
locations dominant precip type will continue to be snow. While as
these showers pass over, effected areas can easily anticipate a
quick one to two inches of fresh snow, however at this time,
amounts for any given location do not appear great enough to
warrant any sort of advisory. A cooling trend will also be in
store for the forecast period as colder air wraps around the low
and moves into the region. As the low meanders it's way toward the
panhandle Saturday night into Sunday, it will begin to weaken and
begin to get overtaken by high pressure to the north in the Yukon.
The interaction between these two features will create a
decent pressure gradient between them over Lynn Canal. As of now,
only have small craft advisory criteria advertised in the
forecast, but gales late Saturday/early Sunday through there may
not be out of the question.

.LONG TERM.../Sunday through Thursday/...As of 10 pm Thursday.
As the upper trof shifts east into Canada, and an upper ridge
moves across the gulf and panhandle, expect that Sunday will give
us a brief break in between weather systems. At the surface, high
pressure will build across the Yukon Sunday morning increasing a
northerly pressure gradient across the northern inner channels,
likely increasing wind speeds through Lynn Canal. Colder air will
also sink further south with 850 mb temperatures dropping to
around -14 C. Although expecting some sunny skies during the day,
Sunday will also be the coldest day of this period. This Sunday,
it being February 2nd, is also a special day, as it will be
Groundhog Day. With the sun out, there is a good possibility one
might see his shadow. What will that mean for Southeast AK?

Back to what we expect the weather to be like next week: our next
weather system will actually be developing in the North Pacific
over the weekend. While the parent low hangs out in the western
Aleutians, a strong front will move across the gulf Sunday and
into the E gulf late Sunday into early Monday. Currently
anticipating the gale force front the approach the outer coast
Monday morning. Precipitation ahead of the front will spread
across the panhandle through the day Monday as multiple impulses,
or shortwaves, will enhance precipitation, especially across the
southern half of the panhandle. There is still possibility of
strong upper level jet supporting a plume of moisture towards the
southern panhandle, or possibly further south. The more
challengingpart of Monday's forecast will be much snow will fall
before changing over to rain? This will depend on how quickly
temperatures will rebound, along with other factors. Model
thickness values keep snow over much of the panhandle through mid-
morning, and perhaps some northern areas into the afternoon. Over-
running snow with significant snowfall amounts is possible,
although temperatures will warm rapidly with the windshift to the
southeast.

After Monday, model agreement dissolves, although the overall
pattern continues to look wet and warmer than normal for February.
Southwesterly flow aloft will continue into mid-week with multiple
waves moving across the gulf and towards the panhandle. Will keep
likely precipitation going through Thursday. Overall forecast
confidence is average.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Winter Weather Advisory until 5 AM AKST early this morning for
     AKZ025.
     Areal Flood Advisory until 9 AM AKST this morning for AKZ028.
MARINE...Small Craft Advisory for PKZ022-031-041>043-051>053.

&&

99/DDH

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