Small Craft Advisory 919, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
401 AM AKST Mon Dec 2 2019

.ANALYSIS AND UPPER LEVELS...

A vertically stacked low remains situated in the northwestern
Bering. Cold air wrapped around the low traveling over warmer
waters, combined with upper support of the low continue to trigger
showers over much of the Bering and Aleutians. A surface trough
is bringing an area of enhanced showers to the eastern Bering and
Kuskokwim Delta coast; its axis is oriented north to south roughly
from Nunivak Island to Nelson Lagoon and shifting eastward.
Looking farther east, patchy fog is forming in the Kuskokwim Delta
under clear skies and high pressure in the low levels. In
Southcentral, the general focus continues to be on a low in the
northern Gulf. This low steered a warm front into the North Gulf
Coast, bringing widespread rain to Prince William Sound and areas
of snow to the Anchorage Bowl and Kenai Peninsula. On the back
side of the low, northwest gales over the Barren Islands have been
observed.

&&

.MODEL DISCUSSION...

The main challenge in the forecast is with snowfall in
Southcentral. Models have been consistent over the past two runs,
keeping the North Gulf low a bit too far east for the Anchorage
Bowl to have a heavy snow event. However, cold air advection
should be strong enough to bring several inches. See the
Southcentral discussion below for further details.

&&

.AVIATION...
PANC...Snow will continue to bring vsby to IFR. Confidence
continues to be moderate regarding snow amounts given easterly
location of driving low, thus it's possible that vsby will
periodically improve to MVFR or VFR.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
A triple point low center which moved to the North Gulf coast this
morning will slowly weaken and then drift south over the Gulf
tonight through Tuesday. In the meantime, broad upper troughing
and cold advection across Cook Inlet will keep moderate snow
potential across the Western Kenai Peninsula through this
afternoon. Snow across the Matanuska Valley overall should be
fairly light with only minor accumulations expected through
tonight. The advisory for snow in the Anchorage Bowl is looking a
little more suspect this morning with the lack of strong dynamics
and low level moisture feed. However, will keep the advisory up
and wait and see what impact the cold advection has when it works
in the morning. Highest snow totals may end up over west and
south Anchorage. Moderate snow potential over the Copper River
Basin will be mostly over the southern and western Basin. Snow
will diminish in most areas tonight, but will linger around until
the upper trough drops south. A drying and cooling trend is
expected through Tuesday.

Storm force westerly winds across the Barren
Island marine zones and western Gulf will slowly diminish tonight
but will maintain gale strength through Tuesday. Outflow wind
conditions over the eastern Kenai Peninsula and across the north
Gulf coast will strengthen today and remain fairly gusty through
Tuesday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Light snow showers will linger along the coast into Tuesday
morning as a frontal boundary stalls near the coast. Weak ridging
sits over the Kuskokwim Delta which has helped with fog developing
over the area. As the sun comes up, and temperatures rise, the
fog will dissipate leaving mostly clear skies into the afternoon
before cloud cover moves in from the west. For the Lower Kuskokwim
Valley, clear skies will persist allowing for temperatures to
drop below 0 tonight and Tuesday night.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
Low pressure over the Bering will keep the southern Bering and
Aleutians with westerly winds and scattered showers through today.
A second low, south of the western Aleutians, will track east
through tonight bringing heavier precipitation to the islands as
it passes. On Tuesday, a new system will push in from the west
with its front making it to the western Aleutians Tuesday morning.
The front will first bring snow to the area but is pulling up
enough warm air for the snow to switch over to rain. The front
will then make it to the Pribilof Islands and eastern Aleutians by
Wednesday morning.

&&

.MARINE (Days 3-5)...

The forecast period commences with weak cyclonic flow over the
Gulf Of Alaska, a ridge axis over the central Aleutians and a
Kamchatka low impacting the western Bering. This pattern will push
eastward Wednesday and Thursday. The primary marine hazard area
will be gales over the western Bering. There is also the potential
for heavy freezing spray near Nunivak Island and over the northern
Bering.

&&

.LONG TERM FORECAST (Days 3-7)...

The models are struggling in the long term forecast period but
there are a couple of consensus items with the global models. The
longwave pattern will feature troughing over the Bering and the
ridge axis will move into southwest Alaska and southcentral
Alaska. There are multiple shortwaves embedded in the upper
trough. It's a very dynamic and unsettled pattern for the Bering.
However, with the high amplitude ridge in place over much of the
mainland expect a more stable pattern and southcentral should get
a break from the precipitation for a few days.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory: 101 121 141
MARINE...Gales: 119 120 132 137 138 172 173 174 175 176 177 178
411 412 413
Storms: 130 131 351 352.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MM
SOUTHCENTRAL ALASKA...BC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
MARINE/LONG TERM...PJS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1237 PM AKST MON DEC 2 2019

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

0836 AM     SNOW             1 NW GLEN ALPS          61.12N 149.71W
12/02/2019  M4.0 INCH                           AK   TRAINED SPOTTER

            OVERNIGHT TOTAL. 1/2SM VIS. TEMP 20F.

0836 AM     HEAVY SNOW       4 ESE KENAI             60.53N 151.11W
12/02/2019  M9.8 INCH                           AK   PUBLIC

            OVERNIGHT TOTAL.

&&

KUTZ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
231 PM AKST MON DEC 2 2019

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

0122 PM     SNOW             1 NW GLEN ALPS          61.12N 149.71W
12/02/2019  M5.0 INCH                           AK   TRAINED SPOTTER

            UPDATED STORM TOTAL 5 INCHES. TEMP 19F

0217 PM     SNOW             1 SW SUTTON             61.71N 148.90W
12/02/2019  M0.5 INCH                           AK   PUBLIC

            6 HR SNOWFALL

&&

KUTZ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
234 PM AKST MON DEC 2 2019

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

0221 PM     SNOW             2 SE EAGLE RIVER        61.30N 149.52W
12/02/2019  M1.0 INCH                           AK   NWS EMPLOYEE

            8-HR SNOWFALL 1 INCH. STORM TOTAL 2 INCHES.

&&

KUTZ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
258 PM AKST MON DEC 2 2019

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

0250 PM     SNOW             2 N MCHUGH CREEK RECREA 61.04N 149.72W
12/02/2019  M3.0 INCH                           AK   PUBLIC

            STORM TOTAL

&&

KUTZ