Gale Warning 335, NWS Juneau, AK

678 
FZAK67 PAJK 270009
OFFAJK

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE JUNEAU AK
309 PM AKST MON DEC 26 2016

OFFSHORE WATERS FORECAST FOR GULF OF ALASKA EAST OF 144W

WIND FORECASTS REFLECT THE PREDOMINANT SPEED AND DIRECTION
EXPECTED. SEA FORECASTS REPRESENT THE AVERAGE OF THE HIGHEST
ONE-THIRD OF THE COMBINED WINDWAVE AND SWELL HEIGHT.

PKZ398-271815-
309 PM AKST MON DEC 26 2016
.SYNOPSIS FOR THE EASTERN GULF OF ALASKA...
A GALE FORCE LOW WILL MOVE INLAND NEAR CAPE DECISION EARLY THIS
EVENING AND RAPIDLY WEAKEN. LOW PRESSURE WILL REMAIN OVER THE
NORTHERN GULF THROUGH TUESDAY NIGHT.   

$$

PKZ310-271815-
GULF OF ALASKA NORTH OF 55 DEGREES NORTH AND EAST OF 144 DEGREES
WEST-
309 PM AKST MON DEC 26 2016

.TONIGHT...W WIND 30 KT. SEAS 17 FT. RAIN SHOWERS. SLIGHT CHANCE
OF THUNDERSTORMS LATE.
.TUE...W WIND 30 KT. SEAS 19 FT. RAIN SHOWERS. SLIGHT CHANCE OF
THUNDERSTORMS.
.TUE NIGHT...W WIND 30 KT. SEAS 19 FT. SLIGHT CHANCE OF
THUNDERSTORMS. 
.WED...SW WIND 25 KT. SEAS 17 FT. W SWELL. SLIGHT CHANCE OF
THUNDERSTORMS. 
.WED NIGHT...W WIND 20 KT. SEAS 15 FT. W SWELL. 
.THU...W WIND 20 KT. SEAS 11 FT. 
.FRI...NW WIND 25 KT. SEAS 14 FT. 
.SAT...N WIND 25 KT. SEAS 15 FT. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
326 PM AKST Sun Dec 25 2016

.SHORT TERM...We have upgraded the statements today continuing on
new paradigms developed last night. Storm force front and
overrunning snow has already begun from Yakutat to Haines to
Gustavus to Angoon and even down to Ketchikan. The rain-snow line
lies precariously along the coast and will make greatest headway
from Dixon Entrance to Sumner Strait but little headway inland
outside of Sitka. Offshore winds in the boundary layer and stable
conditions have limited wind speeds across the Interior and
portions of the coast. As a result, we think the central
Panhandle's temperatures will stall any rises late this afternoon
and this evening. These temperatures will effectively lock in snow
from Wrangell/Petersburg/Kake north into Angoon, Hoonah, Gustavus,
and Juneau through tonight. Another feature will help
precipitation persist as snow for the central and northern
Panhandle Monday.

A developing low identified yesterday is now progged to move into
Cape Decision Monday. Due to the fact that the NAM has not been
consistent with this feature and still pushes it much farther
south, we could not adopt its higher resolution precipitation
fields. Thus, we relied on GFS and ECMWF data with less detail
and more broadscale ideas. Once the front stalls across the
Panhandle tonight, the new low will concentrate more precipitation
over the south. And more impactfully, a deformation band develops
across the central Panhandle tomorrow. With very light northerly
gradients, an implied offshore flow in the low levels, and
enhanced uplift all ahead of this feature, we are moderately
confident that snow rates will increase again tomorrow for much of
the central Panhandle. Based on this information, we upgraded the
advisory for Petersburg/Wrangell/Kake to Warning from 6 PM tonight
to 6 PM Monday for 7 to 14 inches of snow. Haines and Gustavus,
underneath a deeper cold air layer, will see higher snow ratios from
the system tonight and thus more amounts than expected this
morning. Therefore, we will issue new warnings this area. Finally,
Angoon, Hoonah, Tenakee, and Juneau all will have the opportunity
for advisory level snowfall tonight through Monday afternoon:
Hoonah through tonight for 3 to 6 inches and Juneau/Angoon for 4
to 10 inches of snowfall through Sunday. Confidence in highest
amounts are greater for Angoon than for Juneau.

We also raised wind speeds Monday afternoon for the southern
Panhandle behind the low with gusts to 40 mph for Prince of Wales.
These winds and likely those for the southern Inner Channels may need
to be increased further should model consistence remain good.

.LONG TERM...The wave mentioned above will be quickly moving east
and into British Columbia at the beginning of the extended range on
Monday evening. Strong westerly winds will be left over the
southern panhandle with a building southerly pressure gradient over
the remainder of the panhandle. This will be enough to change
precipitation type over to rain for the southern half of the area
with rain mixing in for areas farther to the north.

The next piece of energy in this active pattern will eject into the
gulf and develop a weak surface low which will move into the
northeast gulf early Wednesday. There remains model disagreement on
this low, but another round of enhanced precipitation across the
northern panhandle is likely. The 850 mb temperatures with this
system are progged to be around -6 to -7 C which will lead to
ptype issues. Boundary layer temperatures will be warm due to
southerly low level flow, but as the system approaches the
pressure gradient will reorient leading to a weakening of winds
especially across the northern panhandle. This system will bear
watching as significant accumulations will be possible in areas
that receive snow.

After this system, a very noticeable pattern change is expected to
occur as a broad trough develops over the Bering with an amplifying
ridge developing over the gulf. A strong shortwave feature will
drop southeast over the panhandle Friday into Saturday with another
round of precipitation. As the shortwave passes, winds will rapidly
shift northerly and strengthen over the area. This will usher a
colder airmass into Southeast Alaska. As expected, models are
struggling with the evolution of the pattern thereafter but a drier
period of weather after Saturday appears the most likely scenario
at this point.

Used the 12z GFS/ECWMF for updates through day 4 then transitioned
to WPC guidance for the remainder of the forecast.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Winter Storm Warning from 6 PM this evening to 6 PM AKST Monday
     for AKZ026.
     Strong Wind until midnight AKST tonight for AKZ026-028.
     Strong Wind until 9 PM AKST this evening for AKZ023-027.
     Strong Wind from Monday morning through Monday afternoon for
     AKZ027.
     Winter Weather Advisory from 6 PM this evening to 6 PM AKST
     Monday for AKZ024-025.
     Strong Wind from 6 PM to 9 PM AKST this evening for AKZ022.
     Winter Storm Warning from 6 PM this evening to 6 AM AKST Monday
     for AKZ019-020.
     Winter Weather Advisory from 6 PM this evening to 6 AM AKST
     Monday for AKZ021.
     Winter Storm Warning from 6 PM this evening to 9 PM AKST Monday
     for AKZ029.
MARINE...Storm Warning for PKZ043-051-052.
     Gale Warning for PKZ022-033-035-036-041-042.
     Small Craft Advisory for PKZ013-021-031-032-034-053.
&&

JWA/TPS

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