Gale Warning 711, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
352 AM AKST Sat Dec 7 2019

.ANALYSIS AND UPPER LEVELS...

An upper level ridge in place over the panhandle has become more
amplified as an upper level low over Southwest Alaska lifts
northward. The corresponding surface low is centered over the
eastern Bering and its associated front stretches over the western
Gulf. This has allowed warm, southerly flow to arrive over the
Alaska Peninsula, Kodiak Island, and the Kenai Peninsula.
Temperatures have warmed quickly this morning as precipitation
that initially started as snow in Seward quickly changed over to
rain, and Homer is at a balmy 42 degrees. Meanwhile farther west,
a low continues to spin just west of Shemya. Cold, westerly flow
persists over the southern Bering as the low center slowly drifts
southward and tracks along the Aleutian Chain.

&&

.MODEL DISCUSSION...

Model solutions have come into better agreement compared to the
last few days, however there still remain some uncertainties with
the series of lows that will impact the southern half of the
state over the next few days. Models first diverge by Sun
afternoon as a North Pacific low tracks northward and moves over
the Alaska Peninsula and into the Bristol Bay area by Mon morning. There
is little agreement on exact placement and strength of this low
as it lifts northward over the western part of the state, however
models do agree on a strong front associated with this low
bringing warm/windy conditions to the northern Gulf coast. One
feature model solutions continue to agree on is a strong upper
level ridge remaining in place over the Alaska Panhandle/ALCAN
border through at least early next week. Overall, this translates
into an active pattern with areas of low pressure from the North
Pacific continuously being steered into the southern Mainland.

&&

.AVIATION...
PANC...VFR conditions expected. Wind shear is the main concern
today as winds at the terminal will be out of the north with
stronger southeasterly flow aloft.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Strong south flow aloft will bring a large stream of subtropical
moisture through the area today and tonight. A mixture of
precipitation types are expected around Cook inlet, with rain,
snow, and freezing rain all possible as temperatures slowly climb.
Winds along Turnagain Arm should be fairly strong through tonight
with a strong surface gradient associated with a low in the
western Gulf. Not a lot of precipitation is expected in the Cook
Inlet area through this evening as the low level flow will have an
easterly downsloping component. Precipitation will pick up
somewhat later tonight into Sunday morning as the surface low
moves inland and the downsloping weakens. An even stronger system
will push into the Gulf Sunday afternoon and continue northward
through Sunday night. This will bring strong winds across the
Gulf, and another round of strong winds through Turnagain Arm.
Temperatures will warm even more with this next system.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1-3: Sat through Mon)...

The active pattern across Southwest Alaska starts off with a quick
moving low system tracking from Bristol Bay this morning into the
northern Bering later today. Most areas have transitioned from
snow to rain as this low brings in warming temperatures to the
region. Strong south to southwesterly winds accompany the low,
with possible gusts nearing 50 knots along coastal areas. Colder
air behind this system begins to move back in overnight tonight
into Sunday, allowing any new precipitation to fall as snow. By
Sunday morning, Southwest Alaska will see a brief period of dry
conditions before the focus shifts to a new pattern.

A fast moving North Pacific low will begin to lift north to the
Alaska Peninsula by Sunday afternoon and continue its path
northward through Monday morning. This should be another warm
system, keeping most precipitation falling as rain. Higher
elevations along the Alaska Range will likely see snow during
this event.The heaviest amounts of precipitation will be near
Iliamna to Port Alsworth, which could see up to two inches of QPF
from this system.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1-2: Sat through
Sun)...

A gale force low in the eastern Bering will continue to lift into
the northern Bering through tomorrow morning. Strong southerly
flow moves across the eastern Bering Sunday morning before the
next big system approaches the eastern Aleutians and Alaska
Peninsula Sunday afternoon. Models have come into better
agreement with the placement and strength of this low as it lifts
northward to over Nunivak Island by Mon morning. Winds will likely
peak Monday morning into the afternoon with high end sustained
gales, with possible storm force gusts over the eastern Bering.

Over the western Bering, a low centered over Shemya this morning
will keep a small area of gale force winds in our forecast zone,
but will quickly move into the North Pacific. Weak northerly flow
will follow behind this system through Sunday afternoon,
strengthening to small craft advisory winds overnight Sunday into
Monday.

&&

.MARINE (Days 3 through 5)...
Monday there is a potent low near Bristol Bay which has the
potential to produce gale force winds and also produce light to
heavy freezing spray near Nunivak Island. A second low which will
be south of Adak also has the potential for producing small craft
to gale force winds. As time elapses, the Bristol Bay low
retrogrades towards NE Russia and the Adak low moves towards
Kodiak and phases with another low. Expect the gusty winds and
enhanced sea states to move into the Gulf of Alaska. With this
cold pattern in place, expect the sea ice to grow for both the
Kuskokwim Delta and Bristol Bay.

&&

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

The vagaries of the models continue to influence the confidence
level in the long term forecast period. Looking at both
deterministic and ensemble guidance categorically the confidence
level is below average. There are a few items that can be
gleaned. Expect a highly progressive pattern with the longwave
pattern to retain residence over the Bering and the north Pacific.
There are multiple lows from Kamchatka to southcentral Alaska
this forecast period. Although for the Bering and the NW Pacific
the placement and the intensities of the lows are not in sync. The
storm that will impact Southcentral this weekend will break the
cold snap with temperatures in the Anchorage Metro Area possibly
getting back up into the 40s this Sunday. Also noteworthy and very
plausible, the GFS at this time is suggesting an atmospheric
river will move into Southcentral on Monday.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisor: 155.
MARINE...Gales: 119, 125, 130, 131, 132, 136, 137, 138, 150, 155,
160, 165, 178, 179, 180, 181, 185, 351, 352, 414.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...KO
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AH
MARINE/LONG TERM...PS

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
107 PM AKST Sat Dec 7 2019

AKZ101-111-121-125-135-145-081500-
Anchorage-Matanuska Valley-Western Kenai Peninsula-
Western Prince William Sound-Southeast Prince William Sound-
Susitna Valley-
Including the cities of Anchorage, Eagle River, Indian, Eklutna,
Palmer, Wasilla, Sutton, Chickaloon, Kenai, Soldotna, Homer,
Cooper Landing, Whittier, Seward, Girdwood, Moose Pass, Cordova,
Talkeetna, Willow, and Cantwell
107 PM AKST Sat Dec 7 2019

...Several Strong Systems to bring a Warm Up to Southern
Alaska...

The first in a series of strong storms will push through the
Kenai Peninsula and over the Cook Inlet tonight. Expect gusty
winds through the typical gaps of the Turnagain Arm and Matanuska
Valley to continue through the evening. These winds will move
into Anchorage later tonight, but should only reach about 35 mph.
The precipitation associated with the storm could initially start
as a wintry mix, but it will quickly change over to rain as warmer
air takes over. Regardless, motorists should be prepared for slick
conditions. The second system will be stronger as it tracks
through the Alaska Peninsula late Sunday night. It will bring
another round of heavy precipitation to the Gulf Coast, Kodiak
Island, and parts of Bristol Bay. With even warmer air, most of
this will fall as rain. Strong winds are expected around this
system stretching from Cordova, through Prince William Sound, the
Turnagain Arm, and into Southwest Alaska.

Stay up to date with your local forecast at
www.weather.gov/Anchorage.

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
110 PM AKST Sat Dec 7 2019

AKZ161-081500-
Bristol Bay-
Including the cities of King Salmon, Dillingham, Naknek,
and Pilot Point
110 PM AKST Sat Dec 7 2019

...Several Strong Systems to bring a Warm Up to Southern
Alaska...

The first in a series of strong storms will push through the
Kenai Peninsula and over the Cook Inlet tonight. Expect gusty
winds through the typical gaps of the Turnagain Arm and Matanuska
Valley to continue through the evening. These winds will move
into Anchorage later tonight, but should only reach about 35 mph.
The precipitation associated with the storm could initially start
as a wintry mix, but it will quickly change over to rain as warmer
air takes over. Regardless, motorists should be prepared for slick
conditions. The second system will be stronger as it tracks
through the Alaska Peninsula late Sunday night. It will bring
another round of heavy precipitation to the Gulf Coast, Kodiak
Island, and parts of Bristol Bay. With even warmer air, most of
this will fall as rain. Strong winds are expected around this
system stretching from Cordova, through Prince William Sound, the
Turnagain Arm, and into Southwest Alaska.

Stay up to date with your local forecast at
www.weather.gov/Anchorage.