Small Craft Advisory 796, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
551 AM AKST Mon Dec 19 2016

.SHORT TERM...Active weather continues for Southeast Alaska over
the next 24 hours. The first front of interest is currently moving
over the panhandle early this morning with a second front
following late tonight. It will be more of the same with periods
of moderate to heavy precipitation and gusty southerly winds. The
thunderstorm threat will diminish this morning as the front moves
east of the area, but expect another period of thunderstorm
activity for tonight in the gulf and along the outer coast.

Ptype concerns remain mainly limited to the far northern
panhandle as well as Hyder. The Winter Storm Warning for the
Klondike Highway remains in effect through noon today.
Snowfall rates will diminish in the afternoon before increasing
again late tonight. Heavier precipitation rates have brought the
snow level down to sea level in Haines and Skagway this morning.
Expect as rates decrease later this morning for a change over back
to liquid. As the trough pushed through Hyder last night, winds
shifted southwest and warmed temperatures into the mid 30s. The
Winter Storm Warning was cancelled as a result. Storm total
snowfall in the Hyder area was almost 2 feet. Expect ptype to
remain as a mix there throughout the short term period. Other
areas across the northern and central panhandle have seen snow mix
in overnight, but little accumulation is anticipated. Strong
southeasterly winds through the day combined with weak WAA aloft
tonight is expected to result in less of a mix.

Used the 06z GFS and hi-res guidance for updates to the inherited
forecast.

.LONG TERM...Active weather pattern with a quick zonal type flow
pattern continuing through the week over the north pacific, Gulf
of Alaska and into the panhandle and British Columbia coastline.
Several short waves in the flow will transition across the area.
As the we get closer to the weekend the main axis of the flow will
move shift southward towards Vancouver Island and the Pacific
Northwest of the US.

Models suggesting that colder air aloft and behind the first
couple of short waves on Tuesday and Wednesday will increase the
instability over the eastern gulf will allow for some isolated
Thunderstorms over near the outer coastal terrain. Have not spread
them into the panhandle all that far, if at all for now.

Based on the rough timing from the various solutions, expect a
trough Tuesday afternoon/evening and another on Wednesday. Low
pressure will persist over the northern gulf of alaska and this
will keep showers spreading into the panhandle. Looking for
primarily rain for the coastal areas...though the inner channels
may have sufficient cold air for mix or light snow. Generally
expect that the snow accumulations should be light. Only concern
to this is that the Misty Fjord region on Tuesday night could get
enough snow for an overnight advisory, this is based on the
temperatures currently in the forecast, though Canada's forecast
is for slightly warmer and rain forecast that night.

The forecast into the weekend is for a slightly cooler pattern
with the main flow pattern as far south as 50N so slightly cooler
airmass is in place over the gulf and panhandle. Therefore expect
precipitation to be more in the line of some light snow for the
panhandle. Forecast confidence is average.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Winter Storm Warning until noon AKST today for AKZ018.
     Strong Wind through this evening for AKZ018.
MARINE...Gale Warning for PKZ012-022-041>043-051-052.
     Small Craft Advisory for PKZ011-013-021-031>036-053.
&&

TPS/Bezenek

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