High Wind in Alaska, November 26, 2021

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
527 AM AKST Fri Nov 26 2021

.SHORT TERM.../Through Fri night/ Much quieter short range period
this morning as the system that affected the panhandle yesterday
has moved into Canada overnight. We are now left with westerly
onshore flow and showers for the next 24 hours. The departing low
does have one last shot to play and that is an increased southerly
pressure gradient across the northern inner channels this
morning. Lynn Canal has been blowing southerly 25 kt most of the
night and Skagway has seen wind gusts up to 45 mph.

Not much change in the current forecast compared to previous
forecasts. The cold air that moved in overnight has changed most
places over to snow or at least a rain/snow mix and changed the
precip mode over to convective precip. That is expected to remain
the case until late tonight when the next system from the SW
begins to approach the southern panhandle warming temperatures up
there. Expected snow accumulations remain mostly unchanged with
winter weather advisories remaining up for various times for
Yakutat, Juneau, and Hyder.

As for winds, the stronger winds in the northern inner channels
will gradually diminish today as the northern pressure gradient
relaxes. Otherwise the strongest winds will be out in the gulf
with 25 to 30 Westerly winds blowing for most of the day until
they begin to diminish tonight. Sea remain in the 10 to 18 foot
range through the period. Some breezy conditions across the rest
of the inner channels from the stronger onshore flow, but nothing
more then 25 kt expected.

.LONG TERM.../Saturday through Tuesday/ Jet axis for the start of
the mid range aimed at the far southern panhandle with 250 mb
max winds just south of the area. Reflected at 500 mb and surface
with a low moving up from the N Pacific then over then panhandle.
This gale force low will bring in moderate rain for the southern
panhandle and moderate snow for the Hyder area. Far northern areas
will have a short dry period with offshore flow around the low
and increased northerly and outflow winds along with decreasing
temperatures. By the end of the weekend troughing at 250 mb and
500 mb low over the AK interior keeping a weak low in the NE gulf.
This onshore flow and 500 mb vort max moves in showers over the
Panhandle Sunday. For now not much lift or QPF so significant snow
accumulations not expected, but showers are always uncertain.
Short break in precip Sunday night into early Monday before next
system.

What is known about this system is it will bring in strong winds,
heavy precip, and possibly set up for over running snow event.
Gales currently forecast over the gulf but storm force possible.
Operational models as well as ensembles have been shifting on the
position, track, and strength of this low. Checking EFI and
standardized anomaly tables getting good indication of the higher
precip and winds. NBM tables do keep and warning level snow
amounts probability below 40 percent and for now highest guest
overland were at 50 mph.

For the Saturday system the GFS was stronger and moved the low further
north but it was in better alignment with the Canadian so a blend
was used. This increased winds, pop and QPF for the south and
moved precip a bit further north. For the Monday and Tuesday
system began the process of increasing winds for both the gulf and
inner channels but still did not go with winds as highs as
some operational runs such as the Canadian, which had storm
force. Forecast confidence is still below average due to the run
to run and other model variability.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory until 6 AM AKST Saturday for AKZ025.
     Strong Wind until 9 AM AKST this morning for AKZ018.
     Winter Weather Advisory until midnight AKST tonight for AKZ017.
     Winter Weather Advisory from 3 AM Saturday to 6 AM AKST Sunday
     for AKZ029.
MARINE...Gale Warning for PKZ310.
     Small Craft Advisory for PKZ012-013-021-022-033-036-041>043-
     051>053.

&&

EAL/PRB

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