Winter Storm and High Wind in Alaska, January 1, 2019

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
253 PM AKST Mon Dec 31 2018

.SHORT TERM...Heavy rain and strong winds to welcome in the New
Year in Southeast Alaska. Currently, a strong front is pushing
through interior parts of the Panhandle. Winds have gusted as high
as 60 mph in Ketchikan per marine exchange observations, with
frequent gusts of 40 to 50 mph across the rest of the inside
waters this morning. Heavy rainfall has also accompanied the front
with widespread rainfall totals of up to an inch so far this
afternoon. Snowfall has been confined to the higher elevations of
the Klondike Highway and in Hyder. Several inches of snow will
likely occur in the Hyder area before the precipitation changes to
rain this evening.

Those hoping for a break for the New Year's Eve festivities will be
in luck this evening.  Looks like a break in the winds and rain
through midnight for at least the northern and central Panhandle,
while rain continues over the south as the front gets hung up there.

Attention then turns to a second strong disturbance ejecting
northward towards the Panhandle on the nose of a 140kt Pacific jet
for Tuesday afternoon.  Strong low level baroclinic zone will
enhance the low level wind fields and the moisture transport with
this system.  Surface gradients will be quite favorable for strong
winds throughout the Panhandle.  Sitka-Ketchikan gradients peak
around 13mb with Juneau-Ketchikan gradients around 15mb Tuesday
afternoon.  Low level jet of up to 60 kt at 925mb will couple to the
strong surface gradient forcing and lead to strong gales over the
inside waters with wind gusts of 50 to 60 mph likely in places
favorable to channeled SE winds. Went with a High Wind Warning for
the southern Panhandle where the gradient will be favorable for the
longest.  The EC is showing the potential for a surface wave riding
the front tomorrow afternoon which could complicate the wind field
further north.  Thus went with a High Wind Watch for Juneau to allow
the night shift further time to gauge wind potential there.

Very strong southerly moisture transport through Tuesday evening
will result in significant rainfall amounts Panhandle-wide. 2 to 3
inches of rainfall occurring in a few hours will lead to the
potential for smaller streams and creeks to approach bankfull or
briefly overflow their banks.  Larger river systems will also see
some rises but no major flooding is anticipated at this time. This
moisture transport and dynamic cooling will lead to heavy snowfall
on the Klondike highway.  Thus have issued a Winter Storm Warning
for 5 to 10 inches of heavy, wet snow near White Pass Tuesday
afternoon.

Winds will begin to subside over the south Tuesday night. For areas
further north, expect gusty south winds to continue as CAA commences
behind the front.  Snow levels will slowly fall as showers continue
through Wednesday but at this time not expecting any snow near sea
level.

.LONG TERM...Guidance continues to point toward a more zonal flow
pattern for the latter half of the week. Some colder air will
also be pushed into the area from the Bering Sea area causing
temperatures and snow levels to drop. Confidence is average as
most guidance has a good handle on the overall pattern. However,
there is a series of strong lows that the models are insisting on
bringing N toward Haida Gwaii (one on Thu followed by one on Sat,
through that timing is rather vague). Confidence is rather low as
successive model runs have kept pushing the systems further and
further S. Also confidence on timing is rather lacking as well.

As such, the main changes in the long range focused on the
cooling of temperatures across the area as the cooler air mass
moves in. Highs for late week now may not get above freezing in
some northern areas. Showers are also expected to remain in the
area due to persistent onshore flow, but precip chances remain in
the 30 to 50 percent range due to lack of any confidence on any
strong storms moving in. Wpc used for most changes in the
extended.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind Tuesday afternoon for AKZ019-024-026.
     High Wind Warning from noon to 9 PM AKST Tuesday for AKZ027-028.
     Strong Wind until 3 PM AKST this afternoon for AKZ019-021-023-
     025-027.
     High Wind Watch from Tuesday morning through Tuesday afternoon
     for AKZ025.
     Strong Wind Tuesday afternoon for AKZ021-022.
     Strong Wind from Tuesday morning through Tuesday afternoon for
     AKZ023.
     Strong Wind from Tuesday morning through Tuesday afternoon for
     AKZ020.
     Winter Storm Warning from 3 AM to 6 PM AKST Tuesday for AKZ018.
     Strong Wind Tuesday afternoon for AKZ018.
MARINE...Storm Warning for PKZ052.
     Gale Warning for PKZ012-013-022-031>034-036-041>043-051.
     Small Craft Advisory for PKZ011-021-035-053.

&&

DEL/EAL

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