569
FXAK67 PAJK 232010
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
1110 AM AKST Mon Dec 23 2024

.UPDATE...Model solutions continue to show large spread in the
low tracking across the gulf Wed, enough ensemble members continue
to show the potential track moving closer to shore. A high wind
watch was issued for portions of the southern and coastal
panhandle for possible gusts up to 60 mph.

&&

.SHORT TERM...The active weather pattern continues unabated as
still more wind and rain, and for elevated areas of the northern
panhandle snow, move across the area.

As of the time of writing, satellite and radar imagery show a low
racing N through the panhandle, bringing with it a burst of rain
and southerly winds as it advances. As this low continues moving
N, anticipate snow in the far northern panhandle, notably the
Klondike Highway, where snow levels will remain low enough to
allow continued snow accumulation. Behind the low, anticipate a
brief period of dry, or at least drier, weather to move up from
the S. Some fog development may be possible during this
timeframe, given recent rainfall and cooling temperatures.

Said cooling temperatures will occur largely between Monday
afternoon through early Tuesday morning across many locations,
especially in the north and central panhandle. Driven by cold air
advection as winds shift from southerly back to a more northerly
outflow pattern, a brief dip in temperatures will prove sufficient
to re- entrench cold air in the far northern panhandle, though
what cool air does make it to the central panhandle will be
swiftly driven out by the next advancing system.

The next system, a frontal trough rotating up from the SE along a
broader area of mid-level troughing, will send a band of precip
surging into the panhandle Monday afternoon onwards. As the band
moves northward, it is likely that the Haines Highway will join
the Klondike Highway in experiencing accumulating snow. Snow
levels should drop just low enough that snow melt cooling will
prove sufficient to enable accumulating snow along the more
northerly reaches of the Haines Highway. Anticipate snow totals
through Tuesday morning of around 3-5 inches on the Haines
Highway, and around 7-10 inches for parts of the Klondike.
Otherwise, anticipate between 0.25 and 1.5 inches of rain for the
rest of the panhandle. Strong winds are expected as the various
systems move into the panhandle.

Primary forecast changes were enhancing detail on wind speeds in
the inner channels and for some land-based locations, like Juneau
and Skagway (where wind speeds were increased). Made some
adjustments to QPF on the Haines Highway between Monday night and
Tuesday morning.

.LONG TERM.../Tuesday through Friday/...The mid level low over
the western gulf that has been main steering mechanism that past
few days will finally shift to the east mid week, and then is
replaced by another mid level low over the western gulf by the end
of the week. This shift in midweek will allow a few stronger
systems to sideswipe the panhandle back to back starting christmas
day. Models have come into further agreement that a gale to
potentially storm force system will approach Haida Gwaii before
turning NW and skirting the gulf coast of the panhandle. This will
bring widespread gale force winds to the NE gulf coastal waters
late Tuesday night into Wednesday morning. Coastal communities on
Prince of Wales as well as Metlakatla and Ketchikan could see wind
gusts of 45+ mph throughout the day Wednesday likely peaking in
the afternoon as a trailing low rides along the boundary of the
initial gale force front. Persistent SE flow along the gulf
coastal waters and enhanced surface winds will allow for seas to
build to 20 - 25 ft Wednesday as well, with not much time to
diminish as yet another system approaches from the south on
Thursday. Inner channel winds will also pick up again with the
initial front on Wednesday along with enhanced easterly flow
along the Icy Strait Corridor and Cross Sound as the systems
transit the NE gulf.

Now, on a slightly brighter note, while this pattern will produce
some stormy seas and potential for high winds for coastal
communities, the precipitation amounts are not looking that
impressive as of this forecast. With the synoptic flow aloft, snow
levels are expected to rise to at least 3000 ft in the far
southern panhandle ranging to around 1500 ft along the Icy Strait
corridor by midweek. As such, aside from mountains and ridgetops,
upper elevations along the Haines and Klondike the highways are
the likeliest places to see any accumulating snow as of this
forecast issuance. Stay tuned for further updates as we approach
the Christmas holiday.

&&

.AVIATION...Active weather continues through the next 24 hours as
a windy front moves through this morning, followed by a period of
calmer weather before another weaker front/trough moves in Monday
night mainly for the south. With both of these features, the main
concern for aviation will be the winds, low level wind shear, and
turbulence occurring over a wide area today and tonight with the
strongest occurrences of each mostly over the south and outer
coast. The wind shear will mainly be speed shear, but some
directional shear may be present this morning as winds aloft turn
more southwesterly while surface winds may stay more SE or S. As
for visibility and ceilings, there will be a mix of VFR (during
the calmer breaks) and MVFR or lower (while the frontal bands move
through) due to rain through the period. Freezing levels range
from near sea level in the Chilkat Valley to around 1000 to 3000
ft across the rest of the panhandle, and that will not change all
that much through Tuesday.

&&

.MARINE...Gale force southerly winds racing up the inner channels
as of the time of writing will diminish through Monday morning,
before turning out of the N in many cases as outflow briefly re-
establishes itself. The outflow winds in turn will begin switching
back to the South Monday night into Tuesday morning as another
system moves through. Wind speeds diminish through Tuesday before
becoming elevated once more on Wednesday as a potentially strong
system arrives. Gale force winds are expected for the outer gulf
at times, with gales and small craft conditions for the inner
channels on Monday.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory until 6 AM AKST Tuesday for AKZ318.
     Strong Wind until 6 PM AKST this evening for AKZ318.
     Strong Wind until noon AKST today for AKZ319.
     Winter Weather Advisory from 6 PM this evening to 9 AM AKST
     Tuesday for AKZ319.
     High Wind Watch from late Tuesday night through late Wednesday
     night for AKZ323-328-330-332.
     Strong Wind until 9 PM AKST this evening for AKZ328.
MARINE...Gale Warning for PKZ012-641>643-651-661>664-671.
     Small Craft Advisory for PKZ011-013-021-022-031>036-053-644-652-
     672.

&&

$$

UPDATE...BC
SHORT TERM...GFS
LONG TERM....STJ
AVIATION...EAL
MARINE...GFS

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