Gale Warning 59, NWS Juneau, AK

Southeast Alaska Forecast Discussion...UPDATED
National Weather Service Juneau AK
1022 PM AKST Fri Jan 31 2020

.SHORT TERM...After the passage of a powerful low over the panhandle
on Thursday, the weather for the weekend ahead looks to be more
sedate for much of SE Alaska. The northern and central panhandle
have fallen under the influence of a 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. The dominant precip type will be snow. As these
showers pass over, impacted areas can easily anticipate a quick one
to two inches of fresh snow, with more possible in various locations
if training of a band occurs. 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 its way ESE across the
panhandle Saturday night into Sunday, it will begin to weaken and
get overtaken by high pressure to the north in the Yukon. This will
decrease POP from north to south. The interaction between these two
features will also 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 over these parts late
Saturday/early Sunday 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 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
challenging part 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 wind shift 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 9 PM AKST this evening for
AKZ017.
MARINE...Small Craft Advisory for PKZ022-041>043-051>053.

&&

GFS/DDH

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