Small Craft Advisory 91, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
355 PM AKST Sat Feb 11 2017

.SHORT TERM...Very active weather day across the area as a
powerful and wet low moves through the gulf. First off is the
wind. Several areas have been very windy this afternoon with
observed gusts reaching 60 mph at Skagway, Juneau, and Sitka so
far. Just about every other place has gusted to 30 to 50 mph this
afternoon and places in the southern outer coast and panhandle
are expected to have gusts increase through the evening as a
strong front moves through. High wind warnings remain up for
zones 18, 25, 23, 26, 27, and 28 through tonight as a result and
strong wind headlines are up for just about everywhere else
tonight. As for marine areas, wide spread gales are the norm this
evening with some storm force winds here and there. These winds
are expected to diminish late tonight and tomorrow as the front
that is generating them slowly moves off to the east.

The other concern is the precip. Strong warm air advection has
caused many areas to see rain today. There are exceptions though.
Haines and the Haines Highway are still snowing even through they
have a robust east wind at the moment. Around 4 to 8 inches of
snow has been reported in that area today. This is likely a result
of the heavy precip rates that moved into the area and they will
likely remain snow or at least a rain/snow mix through around 10
pm before precip rates drop off. That should allow the ptype to
transition to all rain. Expect another 4 to 8 inches of snow there
before that happens though. Winter storm warning issued as a
result.

Hyder is the other low elevation exception. They have been snowing
all day and reported upwards of 8.5 inches this morning with a
snow to liquid ratio of around 20 to 1. Decided to extend the
winter storm warning there until noon Sun as it looks like it will
take a little longer for the heavier precip to get out of there.

White Pass it the Third exception. Webcam images have continued to
show widespread blowing snow and very low visibilities there. A
blizzard warning remain in effect for that area.

Heaviest precip is expected this evening for the northern
panhandle and through tonight and early tomorrow for the southern
panhandle. We get a break for tomorrow as the front moves off to
the east. There still will be showers around through most of them
will be in the form of rain despite the weak cold air advection
that is coming through in the wake of the front. Yakutat will
likely see snow again late tonight and tomorrow with low
accumulations. The rest of the panhandle will likely remain rain
for low elevations as the southerly flow should overwhelm the
cold advection and keep temps warm enough for rain.

Main changes today were for local effect for ptype and also for
wind. Mainly used nam/gfs for guidance today.

.LONG TERM...Active weather pattern continues through the week
as more system move into the AK gulf. 300 mb SW jet aiming at the
panhandle until Wed then shifts to the south with much weaker flow
toward the weekend. The surface systems will track up from the N
Pacific with warm SW flow at mid levels. At 500 mb a low drops SW
over the AK interior then become quasi stationary over the
Aleutians by early Tuesday and lasting into about Thursday.
Toward the weekend weaker mid level pattern with potential for a
drier and cooler period of weather.

Next gale force front moves into the western AK gulf Sunday night
with more rain and only a mix of snow at higher elevations. Once
again long fetch of moisture resulting in high QPF amounts with
potential snow accumulation at higher elevations. Parent low at
the surface remains over the Aleutians moving frontal bands
eastward. For Wednesday large model spread on development of a low
along the next frontal band in the central gulf. GFS develops a
storm force system while NAM/Canadian/ECMWF have only gale force.
As the 500 mb low leaves the Aleutians the surface low begins to
track to the NE with diminishing winds and pop. Cooler airmass at
850 mb moves in from the west at this time so started to lower
forecast temps late in the week.

Used a blend of NAM/Canadian as they have been more consistent
run to run and were mostly in line with previous forecast. ECMWF
has been shifting position of the mid week low each run and GFS is
the outlier with the storm force. Updated later periods with
ensemble WPC. Forecast confidence is below average.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...High Wind Warning until midnight AKST tonight for AKZ026.
     High Wind Warning until 3 AM AKST Sunday for AKZ027.
     Strong Wind until 9 PM AKST this evening for AKZ017-020>022-024.
     High Wind Warning until 9 PM AKST this evening for AKZ023-025.
     High Wind Warning until 3 AM AKST Sunday for AKZ028.
     Winter Storm Warning until noon AKST Sunday for AKZ029.
     Winter Storm Warning until midnight AKST tonight for AKZ019.
     High Wind Warning until 6 AM AKST Sunday for AKZ018.
     Blizzard Warning until 6 AM AKST Sunday for AKZ018.
MARINE...Storm Warning for PKZ036-041>043.
     Gale Warning for PKZ011>013-021-022-031>035-051-052.
     Small Craft Advisory for PKZ053.
&&

EAL/PRB

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
325 AM AKST SUN FEB 12 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0430 PM     BLIZZARD         15 NE SKAGWAY           59.63N 135.03W
02/11/2017                   XXX                XX   OTHER FEDERAL

            BLIZZARD CONDITIONS NEAR WHITE PASS, AND ROAD CLOSED
            THROUGH PASS CLOSED DUE TO POTENTIAL AVALANCHE CONCERNS

0430 PM     HEAVY SNOW       6 S HAINES              59.15N 135.44W
02/11/2017  M16.0 INCH       PKZ012             AK   TRAINED SPOTTER

            TOTAL SNOW FOR THE EVENT.

0900 PM     HEAVY SNOW       HAINES                  59.24N 135.44W
02/11/2017  M7.7 INCH                           AK   CO-OP OBSERVER

            7.7 INCHES OF SNOW 8 AM TO 9 PM. TOTAL STORM EVENT 13.9

0100 AM     HEAVY RAIN       SITKA                   57.05N 135.34W
02/12/2017  M3.39 INCH                          AK   ASOS

            3.39 INCHES IS A NEW DAILY RAINFALL RECORD

0100 AM     HEAVY RAIN       JUNEAU                  58.30N 134.41W
02/12/2017  M2.28 INCH                          AK   NWS EMPLOYEE

            2.28 INCHES AT NWS FORECAST OFFICE, DAILY PRECIP TOTAL

0100 AM     HEAVY RAIN       JUNEAU                  58.30N 134.41W
02/12/2017  M1.86 INCH                          AK   ASOS

            1.86 INCHES IS A NEW DAILY RECORD

&&

BMB