290
FXAK68 PAFC 230201
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
501 PM AKST Sun Dec 22 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Tonight through Wednesday)...

Precipitation remains largely downsloped out this afternoon, with
some breaks of low elevation sunshine being observed at some
inland locations, including Anchorage. The pattern remains the
same as the past several days, with low pressure tracking from the
southern Gulf toward Kodiak Island and a series of shortwave
troughs lifting north across Southcentral Alaska. Freezing rain,
or meteorological rain with below-freezing surface temperatures,
will continue to be a possibility at times for many locations
across Southcentral through Monday night. Snow will be limited to
elevations above 2000-3000 ft, with the exception of the potential
for an inch or so of snow accumulation in the western Copper River
Basin near Eureka and Tahneta Pass this evening as cold
northeasterly flow leads to some upslope precipitation for parts
of the Copper River Basin. Greater snow accumulations (up to
around 4 inches) are likely along the Richardson Highway south of
Tonsina, though this will be mixed with up to a tenth of an inch
of freezing rain. Along the Edgerton Highway, sleet is expected to
mix with snow as warm air is in place across the southern Copper
Basin while a deep layer of cold air remains near the surface.

Monday morning, the main axis of the upper level trough shifts
north across Southcentral, bringing the next significant chance of
precipitation spreading inland past the coastal mountains. The
Copper River Valley can be expected to get in on the action as it
looks like a small amount of snow (less than one inch) will be
able to accumulate in the valley. However, there is significant
uncertainty with what this will do for portions of the southern
Copper Basin, where some model guidance suggests the push of
southeasterly winds, which are expected to reach the surface,
bring temperatures above freezing for some time. More likely,
though, the depth of antecedent cold air will prevent temperatures
from warming that significantly and instead peak somewhere in the
20s. A shallowing of the cold air near the surface will thus make
freezing rain a possibility during this round of precipitation on
Monday. For the Cook Inlet region, the Anchorage Bowl and the
southern Susitna Valley are the most likely focus for freezing
rain potential. Though this would likely be only a brief period
for Anchorage, there is a greater chance of accumulating
precipitation in the Susitna Valley, particularly south of Willow,
however not all models are biting off on that solution just yet.
For the Kenai Peninsula, warmer temperatures will keep any
precipitation rain, and the Matanuska Valley looks to stay mostly
dry.

The southerly push of warmer air also coincides with a weakening
down-inlet pressure gradient, which will allow for a straightening
of the Turnagain Arm wind, likely impinging on the south side of
Anchorage for a time on Monday afternoon, which could bring
temperatures locally close to 40. However, cooler air begins to
move in aloft on Monday night, and though surface temperatures may
remain above freezing for a time precipitation changes over to all
rain or snow, and freezing rain becomes less of a concern across
Southcentral. Tuesday and Wednesday, shortwaves continue to lift
across the area, though downsloping remains, so expect continued
wet conditions along the coast and periods of very light
rain/snow inland.

Quesada

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(Days 1 through 3: Through Wednesday)...


Additional precipitation will still be possible across
the greater Bristol Bay region, tonight into Monday. A warm layer
of air between freezing layers aloft and at the surface, will
provide a favorable setup for freezing rain, with the best chance
for up to a tenth of an inch of freezing rain between Koliganek
and Dillingham. A Winter Weather Advisory has been issued through
Monday morning due to this potential. The entire column will cool
below freezing by Monday afternoon, allowing any lingering
pockets of freezing rain to switch over to snow.

The low which brought freezing rain and mixed rain/snow to
Southwest Alaska over the previous several days has weakened
north of Cold Bay. This will consolidate Sunday night over Kodiak
Island with a low in the northern Gulf. Meanwhile, the front of a
strong North Pacific system will sweep eastward across the the
Aleutian Island chain Monday. Storm force winds will initially be
possible as the front reaches the Western Aleutians, but the
front should quickly weaken to gale force before it lifts
northeast into the southern Bering Monday afternoon. Models
continue to struggle to resolve rapid formation and dissipation of
multiple triple-point lows along this front, and there may be
changes to the wind and precipitation forecast for Monday into
Tuesday due to this inherent uncertainty for the location and
development of these smaller lows. There is a general consensus
for the main low to eventually shift or redevelop towards the
AKPen by Tuesday afternoon. Strong northeast winds will also
continue to spread across the Bering Sea as a colder air mass
begins to spread south from the Arctic Tuesday night into
Wednesday.


&&

.LONG TERM FORECAST (Days 4 through 7: Thursday through
Sunday)...

A broad upper level trough stretches from the Arctic all the way
down to the North Pacific and northern Gulf on Wednesday, with
several surface lows forming in the pattern. The trough axis will
shift eastward into the weekend, with the main cluster of surface
lows taking shape in the central Gulf. A ridge will start moving
into the western Bering late Thursday before moving over mainland
Alaska by late Saturday. Behind the ridge will be a second upper
level trough moving in from Kamchatka over the western Aleutians
and Bering by Saturday. The Bering ridge and a ridge forming over
Southeast Alaska will interact over the interior on Sunday,
resulting in a strong ridging pattern over most of mainland Alaska
by the end of the extended forecast period.

While the troughing pattern persists through Saturday, the series
of lows and fronts forming near the Alaska Peninsula, Eastern
Aleutians, and Kodiak will help provide repeated rounds of heavy
rains along the coastline until the ridge builds in. Bitter cold
air will begin to fill in over interior Southwest Saturday before
spreading into portions of Southcentral on Sunday, continuing
beyond the end of the extended forecast period.

&&.AVIATION...

PANC...VFR conditions with light northerly winds will persist
through Monday morning. There remains a slight chance this evening
of some very light sprinkles of rain over the terminal. The next
shortwave and surface trough will move across the Anchorage Bowl
early Monday morning. These will bring a better chance for
precipitation to the terminal early Monday morning through midday.
With temperatures hovering near freezing, the precipitation may
fall as a period of freezing rain. Any ice accumulation is
expected to be light, nothing more than a glaze of ice.

The upper-level wave will also bing an increase in southeasterly
winds at mountaintop level and through Turnagain Arm. This will
likely result in a period of LLWS Monday morning. By midday, there
is a chance that the southeasterly Turnagain Arm wind lifts into
west Anchorage and across the terminal. Any southeasterly wind
over the terminal will likely become northerly again by Monday
evening.

&&


$$

165
FXAK69 PAFG 222122
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
1222 PM AKST Sun Dec 22 2024

.SYNOPSIS...
An active stretch of weather ongoing with strong winds from Point
Hope to St. Lawrence Island. Snow will also be developing tonight
with light snow chances around Fairbanks and heavier snow in the
Northern Interior and Brooks Range. This progresses west tomorrow
through Wednesday with heavy snow expected from the Dalton Highway
west to Ambler and south to the Nulato Hills. Lighter snow is
expected towards the YK Delta and Eastern North Slope.

&&

.DISCUSSION...
Key Weather Messages...

Central and Eastern Interior...
- Snow expected in the Northern Interior tonight into tomorrow.
- Chances for snow from Tanana to Delta Junction tonight into
tomorrow morning.

- Gusty winds and blowing snow through the AK Range Monday
afternoon to Tuesday afternoon. Winter Weather Advisories issued.

- Blowing snow for the Dalton Highway from Atigun Pass south.

- Heavy snow expected Tuesday into Wednesday around the Dalton
Highway and Bettles.

- Snowfall totals through Wednesday Night:
- Dalton Highway to Bettles 6-12 inches.
- Winter Storm Warning issued for Bettles/Allakaet/Hughes.
- Yukon Flats 3 to 7 inches (highest west of Fort Yukon)
- Tanana to Circle 1-3 inches (Highest towards Tanana).
- Fairbanks to Eagle up to 2 inches (Highest in the terrain).

West Coast and Western Interior...
- Strong northerly winds from Point Hope to St. Lawrence Island.
- Gusts 60-70 mph in St. Lawrence Island
- Heavy snow in the Western Interior from the Nulato Hills to the
Brooks Range. Snowfall rates up to 1-2 inches per hour are
possible.
- Lighter, but much needed snowfall elsewhere.

- Snowfall totals through Wednesday Night:
- Ambler to Shungnak 6-12 inches (with up to 18 inches from
Shungnak east.
- Winter Storm Warning issued.
- Hughes to Nulato Hills 6-12 inches.
- Winter Storm Warning issued for Huslia.
- Kaltag to Yukon Delta Coast 4 to 8 inches with blowing snow
along the YK Delta Coast and around Stebbins/St. Michael.
- Winter Weather Advisories Issued.

North Slope and Brooks Range...
- Seasonably chilly weather today and tomorrow.

- Windy near Point Hope with gusts up to 60 mph through Monday
Afternoon.

- Snow develops in the Brooks Range tomorrow evening and continues
heavy at times Tuesday and Wednesday.
- Snow develops from Nuiqsut east tomorrow night into Tuesday
morning and continues through Wednesday.
- Blowing snow expected in Atigun and Anaktuvuk Passes Monday
into Tuesday morning.

- Snowfall totals through Wednesday Night:
- Atigun and Anaktuvuk Passes 6 to 8 inches.
- Umiat and Eastern Beaufort Sea Coast 3 to 6 inches.

Analysis and Forecast Confidence...
An arctic high over Siberia is interacting with a low in the
Southern Bering causing strong northerly winds from Point Hope to
St. Lawrence Island. Gusty winds will continue through midweek
but gradually weaken Tuesday and Wednesday as the pressure
gradient weakens. At this point, snow will be ongoing as moisture
runs into an arctic front. Heavy snow is expected for much of
Northern Alaska from the Nulato Hills to the Brooks Range. A
winter storm warning has been issued for Shungnak, where total
snowfall amounts are expected be around 12-18 inches. The heaviest
of which will fall on Tuesday with snowfall rates of up to 1-2
inches per hour at times with narrow, mesoscale snow banding.

Extended Forecast Days 4-7...
Snow will be ending gradually by Saturday as the arctic front
slides from west to east. Snow will be possible in the Central
Interior once again on Friday, then in the Eastern Interior Friday
night into Saturday. Temperatures then drop well below normal this
weekend into next week. This has the potential to be the coldest
air of the year for the West Coast and Western Interior with
temperatures potentially as low as the 20s and 30s below zero. In
the Central and Eastern Interior, there are low chances for
temperatures in the 40 below zero range. Most likely this will be
relatively short lives as southerly flow tries to return by the
middle of next week.

Coastal Hazard Potential Days 3 and 4...None.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...High Wind Warning for AKZ801.
Winter Weather Advisory for AKZ847>850.
Winter Weather Advisory for AKZ812-832.
Winter Storm Warning for AKZ819-828.
High Wind Warning for AKZ820-821-827.
Winter Weather Advisory for AKZ824-825.
Winter Storm Warning for AKZ831.
Winter Weather Advisory for AKZ809.
PK...Small Craft Advisory for PKZ801.
Heavy Freezing Spray Warning for PKZ801-816-817-851-854.
Brisk Wind Advisory for PKZ802-803-812-850-853.
Gale Warning for PKZ804.
Gale Warning for PKZ805>807-810-856.
Brisk Wind Advisory for PKZ808-855.
Gale Warning for PKZ809.
Gale Warning for PKZ811-852-857.
Storm Warning for PKZ816.
Storm Warning for PKZ817-854.
Storm Warning for PKZ851.
Brisk Wind Advisory for PKZ858.
&&

$$

Bianco

401
FXAK67 PAJK 230105
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
405 PM AKST Sun Dec 22 2024

.SHORT TERM...

.LONG TERM.../Tuesday through Friday/...The mid level low over
the western gulf that has been main steering mechanism that past
few days will finally shift to the east mid week, and then is
replaced by another mid level low over the western gulf by the end
of the week. This shift in midweek will allow a few stronger
systems to sideswipe the panhandle back to back starting christmas
day. Models have come into further agreement that a gale to
potentially storm force system will approach Haida Gwaii before
turning NW and skirting the gulf coast of the panhandle. This will
bring widespread gale force winds to the NE gulf coastal waters
late Tuesday night into Wednesday morning. Coastal communities on
Prince of Wales as well as Metlakatla and Ketchikan could see wind
gusts of 45+ mph throughout the day Wednesday likely peaking in
the afternoon as a trailing low rides along the boundary of the
initial gale force front. Persistent SE flow along the gulf
coastal waters and enhanced surface winds will allow for seas to
build to 20 - 25 ft Wednesday as well, with not much time to
diminish as yet another system approaches from the south on
Thursday. Inner channel winds will also pick up again with the
initial front on Wednesday along with enhanced easterly flow
along the Icy Strait Corridor and Cross Sound as the systems
transit the NE gulf.

Now, on a slightly brighter note, while this pattern will produce
some stormy seas and potential for high winds for coastal
communities, the precipitation amounts are not looking that
impressive as of this forecast. With the synoptic flow aloft, snow
levels are expected to rise to at least 3000 ft in the far
southern panhandle ranging to around 1500 ft along the Icy Strait
corridor by midweek. As such, aside from mountains and ridgetops,
upper elevations along the Haines and Klondike the highways are
the likeliest places to see any accumulating snow as of this
forecast issuance. Stay tuned for further updates as we approach
the Christmas holiday.

&&

.AVIATION...Today you only flew if you needed too with the incoming weather
front. Copious amounts of pireps today of Wind shear at airports in
the 10 to 15 kt range with reports otherwise of Moderate to Severe
Turbulence. THe next front has a low level jet about 3000 feet of
50 to 65 kt that flow from roughly Haida Gwaii to to the NNW. The
band moves over Prince of Wales between 03z and 06z this evening and
weakens winds in the NE gulf from Cross Sound to Prince William
Sound overnight at 40 to 45 kt. Behind the front there are moderate
30 to 35 southwest winds to rush into the coastal areas so the shear
direction will be swapping to a SW.

Tonight will be more of the same. For Monday conditions by morning,
although some turbulence may continue. The southern panhandle near
Dixon Entrance will see the next feature approaching with strong
winds and rain returns.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory until 6 AM AKST Monday for AKZ319.
Strong Wind through late tonight for AKZ323.
Strong Wind until 6 PM AKST this evening for AKZ327.
Strong Wind from 9 PM AKST this evening through late tonight for
AKZ327.
Strong Wind until midnight AKST tonight for AKZ328.
Strong Wind until 9 PM AKST this evening for AKZ329.
Strong Wind from midnight AKST tonight through late tonight for
AKZ329.
Strong Wind from 6 PM to 9 PM AKST this evening for AKZ330-332.
MARINE...Storm Warning for PKZ661>664-671-672.
Gale Warning for PKZ012-013-022-031-036-641>644-651-652.
Small Craft Advisory for PKZ011-021-032>035-053.

&&

$$

SHORT TERM...Ferrin
LONG TERM....STJ
AVIATION...Bezenek
MARINE...Ferrin

Visit us at http://www.weather.gov/Juneau