Small Craft Advisory 817, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
401 PM AKST Mon Dec 26 2016

.SHORT TERM...A potent 975 mb low pressure system will be moving
inland this evening in the vicinity of Cape Decision and Port
Alexander. The system will rapidly weaken as it moves inland and
become an open surface trough by late tonight. Strong
southeasterly winds this afternoon ahead of this system will
quickly shift to the southwest in the next few hours. Pressure
rises behind weakening low will spread southerly winds through
the entire panhandle, last reaching the northern panhandle by
Tuesday afternoon. The southerly low level flow will scour out any
of the remaining near freezing temperatures across the central
panhandle which will change the showers to all liquid on Tuesday.
Snow at sea level by tomorrow afternoon is expected to be confined
to the far northern panhandle and some interior areas such as the
Mendenhall Valley may still see some snow mixing in. Therefore,
little or no snow accumulation is expected on Tuesday aside from a
few inches in the far northern panhandle.

The Winter Storm Warning continues for Hyder through 9 pm this
evening. Thereafter, weakening forcing will result in decreased
snowfall rates. Otherwise, inherited advisories/warnings were
cancelled earlier today.

Used the 12z NAM and high-res guidance for updates to the previous
forecast.

.LONG TERM...The zonal type flow from the Pacific into the
Pacific northwest will continue to about midweek until a trough
deepens and over the western gulf Tuesday night and then the
trough will move through southeast alaska Thursday. A ridge will
build across the western half of the state then eastward. The
trough being replaced by the ridge will lead to pattern shift from
the weekend into next week as higher pressure with a cooler and
drier pattern for next week.

Expect showers to continue into Thursday before they end from the
northwest. The models to bring one last  short wave to the
northern British Columbia coast Wednesday night. Some
precipitation may extend north to spread some precipitation north
of Dixon Entrance late Wednesday and early Thursday.

Only made small changes essentially to the forecast package,
overall model consensus was fairly solid with the trough and
ridging plans.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind until midnight AKST tonight for AKZ027.
     Strong Wind until 6 PM AKST this evening for AKZ028.
     Winter Storm Warning until 9 PM AKST this evening for AKZ029.
MARINE...Gale Warning for PKZ035-036-041-042.
     Small Craft Advisory for PKZ031>034-043.
     Small Craft Advisory due to Seas for PKZ022-051>053.
&&

TPS/Bezenek

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