Blizzard Warning 1, NWS Juneau, AK

223 
WWAK47 PAJK 171447
WSWAJK

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE JUNEAU AK
547 AM AKST TUE JAN 17 2017

AKZ018-171600-
/O.EXP.PAJK.BZ.W.0001.000000T0000Z-170117T1500Z/
TAIYA INLET AND KLONDIKE HIGHWAY-
INCLUDING THE CITY OF...SKAGWAY
547 AM AKST TUE JAN 17 2017

...BLIZZARD WARNING WILL EXPIRE AT 6 AM AKST EARLY THIS MORNING...

THE STRONG SOUTHERLY PRESSURE GRADIENT THAT PRODUCED BLIZZARD
CONDITIONS HAS DIMINISHED SIGNIFICANTLY OVERNIGHT. HIGH WINDS
STRONG ENOUGH TO PRODUCE BLOWING SNOW WITH VISIBILITIES TO 1/4
MILE OR LESS HAVE SUBSIDED. STRONG SOUTHERLY WINDS WITH GUSTS TO
50 MPH WILL CONTINUE THROUGH MID MORNING HOWEVER VISIBILITIES ARE
EXPECTED TO REMAIN 1/2 MILE OR MORE. 

WIND SPEEDS OF 70 MPH WITH GUSTS TO 80 MPH WERE REPORTED OVERNIGHT
NEAR WHITE PASS. 

THIS WILL BE THE FINAL STATEMENT ON THIS EVENT.


$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
344 PM AKST Mon Jan 16 2017

.SHORT TERM...The cyclone and front responsible for strong gusty
winds (with a few gusts close to 70 mph around Sitka yesterday
evening) and anywhere between a half and 2 inches of rainfall the
last 12 hours, is now jumping ashore across the Panhandle into
Canada. Strong lift from vorticity and orographics will keep
showers enhanced early on this evening but the vorticity will
quickly retreat into Canada tonight thus diminishing shower
activity overnight. Monday, weak 500 mb ridging ahead of a
developing system to the south will limit snow and rain showers as
isolated across the north. This system to the south will then
begin to spread rain for the afternoon over the southern and
south central zones by Monday afternoon.

Strong cold air advection at 850 mb will push in behind the
dynamics exiting into Canada. Snow will likely begin mixing in
with the rain across Yakutat tonight and the northern panhandle
very late tonight and early tomorrow morning. Surface temperatures
will fall more slowly, which explains in some cases why we held
back the snow changeover to tomorrow morning. Should the
atmosphere begin to support snow late tonight; however, much of
the precipitation may be done. Model QPF is much drier than what
our pops indicate.

Winter Storm for blizzard conditions and blowing snow is still
ongoing for White Pass and the Klondike through early Tuesday
morning. The heavy snow, which it was initially issued for, will
wind down early this evening, and the statement still advises for
blizzard conditions and near zero visibility in high winds. High
winds to 60 mph will plague lower elevations of the Klondike
including Skagway as the low jumps inland into the Canadian Yukon
this evening. High end gales will howl through Northern Lynn
Canal tonight. Windy conditions for the rest of the Panhandle
will come down through this evening. Tomorrow, we expect lighter
north winds as northerly gradients begin to develop in response to
a low developing well to the south.

Temperatures will be quite a bit cooler tomorrow than the previous
few days (in the 30s) with Kake potentially seeing rain and snow
developing as the precipitation builds from the south. Areas to
the south will generally see rain by tomorrow afternoon.

Amendments to the forecast tomorrow was best handed by NAM/GFS
Monday.

.LONG TERM...Models have come into better agreement on a
developing wave moving north into the eastern gulf on Wednesday
and over the northern panhandle Wednesday night. With increased
model agreement, significant changes were made to this portion of
the forecast. Gale force winds were introduced in Dixon Entrance,
the southeast gulf and into Clarence Strait. Additionally, strong
wind gusts of 40 mph are likely early Wednesday across Prince of
Wales island and into the Ketchikan area. At this time, it appears
like stability in the boundary layer combined with the easterly
pressure gradient orientation will preclude any high wind gusts.
But this will continue to be monitored. As the low tracks
northward and over the panhandle, a southerly push of winds will
move through the inner channels. Will need to watch westerlies
after the low passes especially in the Sitka area. Along with
winds this system will bring another round of steady
precipitation. Expect some snow to mix in at the onset across the
central and northern panhandle, but accumulations will be limited.
1000-850 mb thicknesses remain around 1300m for most of the event
so rain should be the predominate ptype at sea level.

The remainder of the extended range continues to feature model
disagreement and low confidence. However, latest ensembles and
operational models do not paint a pretty picture for snow lovers
at sea level as we head into next week.

Used the 12z GFS/18z NAM through 84 hours then the latest WPC
guidance from thereafter.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind until 6 PM AKST this evening for AKZ022-025.
     Strong Wind until 3 PM AKST this afternoon for AKZ023.
     Strong Wind until 9 PM AKST this evening for AKZ019.
     High Wind Warning until midnight AKST tonight for AKZ018.
     Winter Storm Warning until 6 AM AKST Tuesday for AKZ018.
     Strong Wind until 6 PM AKST this evening for AKZ017.
MARINE...Gale Warning for PKZ011>013-021-022-031-041>043-051>053.
     Small Craft Advisory for PKZ032>036.
&&

JWA/TPS

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