Gale Warning 251, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
330 PM AKST Sat Nov 7 2020

.SHORT TERM...A low pressure system tracking NE along the
Aleutians has caused increasing high clouds over the region today,
keeping temperatures from warming as much as expected across the
north. The assoc warm front extending out across the NE gulf will
cause snow to move into Yakutat later Saturday night then become
mixed with and change over to rain by Sunday morning. The precip
will spread over the northern panhandle through Sunday morning,
then to the far SE corner of the panhandle later in the afternoon
or even early evening. Snow is expected initially, but strong
southerly winds will work quickly to change the snow to rain
through the day near sea level. Some accumulations of up to 2
inches are possible before the change over. For the Mendenhall
Valley, Haines, and Skagway closer to 4 inches are expected and
White Pass is expected to see 6-9 inches of snow.

Winds with the front increase to 35-50kt over the outside waters
on Sunday. Cross Sound increases to 35kt in the afternoon and
Clarence Strait to gale force as well Sunday evening. These strong
winds will work to raise snow levels above 1000ft across the
north and 2-5kft for the south Sunday evening. Heavy rain is
expected during this period.

The rain on top of a the snow pack across the north is going to
make for very poor roadway conditions. Additionally, storm drains
and culverts will likely clog with a mix or rainwater, slush, and
wet snow. Snow loading on roofs and sheds may become an issue as
well due to the very high water content of snow. Similar concerns
exist for aircraft stored outdoors and moored, unattended
vessels.

The low will track E-SE across the area through Monday. Expect
rain to transition to showers at that point and winds to shift
west behind the front, then northerly behind the low. CAA behind
the system will likely be enough for some snow to mix back in with
the showers Monday afternoon/evening, but the precip will also be
ending around that point and thus too short-lived for
accumulations.

.LONG TERM.../Monday through Saturday night/...As of Friday
evening. At the start of the extended forecast period, a low will
be sliding south along the coast. This low is expected to bring
heavy rain across the panhandle through Sunday. Rain chances will
begin to diminish through the day on Monday from North to South
with areas across the southern panhandle and along the coastal
mountains hanging onto the precipitation the longest. Winds
associated with the frontal band will be on the decreasing trend
Monday, diminishing from small craft through the southern inner
channels to 15 kts or less. Surface ridging quickly builds in
behind the exiting low pressure displacing it SSE of Haida Gwaii.
This will allow for a quick dry period Tuesday before the next
weather systems arrives late Tuesday night into early Wednesday.

By Wednesday, a parent low pressure system will be located in the
Bering Sea. Guidance supports an associated triple point low to
form along the Aleutians which will then slide east into the NE
Gulf coast. There is potential for this system to bring
significant QPF totals across the panhandle with periods of heavy
precipitation. By early Thursday morning, the parent low will
have moved into the Northern Gulf pushing onshore an additional
uniform frontal band. P-type is a concern with this system as
colder temperatures will be in place from Tuesdays CAA. Depending
on how strong the southerly WAA ahead of the approaching system
is, the northern panhandle could see significant snow
accumulations.

From Thursday through Saturday, a low looks to become locked in
on the central Gulf keeping precipitation chances elevated
through the remainder of the extended period as multiple vortices
approach the panhandle.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory from 7 AM to 6 PM AKST Sunday for AKZ025.
     Strong Wind Sunday afternoon for AKZ022.
     Winter Weather Advisory from 7 AM Sunday to midnight AKST Sunday
     night for AKZ019.
     Winter Storm Warning from 9 AM Sunday to 6 AM AKST Monday for
     AKZ018.
     Strong Wind Sunday afternoon for AKZ017-018.
MARINE...Storm Warning for PKZ052.
     Gale Warning for PKZ022-042-043-051.
     Small Craft Advisory for PKZ011>013-021-031>034-041-053.

&&

Ferrin/CC

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