Graphical Hydro Meteorological Discussion

000
FXAK68 PAFC 271345
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
445 AM AKST Thu Jan 27 2022

.ANALYSIS AND UPPER LEVELS...

A strong ridge of high pressure is entrenched over the Bering Sea.
A trough of low pressure is oriented north-south across the
central part of the state, just to the east of the blocking high
over the Bering. A large low pressure system south of Kodiak is
moving north across the western Gulf, while another strong low
pressure system is south of Attu Island, moving northwest.

Precipitation, mainly in the form of snow continues across much
of South Central, with the heaviest confined to the eastern Kenia
and PWS areas. Farther inland conditions were generally dry.

Temperatures were mainly in the teens and 20s over Central and
South Central, the exception is eastern Prince William Sound with
temps in the 30s and rain. Temperatures across southwest Alaska
ranged from the single digits to teens above zero, to the single
digits and teens below zero in far southwest Alaska. The Aleutians
saw readings generally in the 20s and 30s.

&&

.MODEL DISCUSSION...

Models remain in good agreement with the handling of synoptic
features through Saturday. A ridge of high pressure remains in
place over the Bering Sea. The upper level trough, stretching
north-south across central/western Alaska will remain in this
general area through today. The trough will wiggle somewhat as a
reinforcing impulse of energy moves south along the trough and the
low pressure system moving north across the western Gulf gets
wrapped up into the southern portion. As these two features merge,
models show the result as a large low pressure system with
multiple impulses of energy rotating around the center over the
western Gulf through Saturday drawing moisture in from the Gulf
of AK. This creates a widespread, long duration event over
Southcentral which will persist through Friday for Anchorage and
the Valley, and through Saturday for coastal areas from the
Eastern Kenai eastward. While this is a favorable setup for snow
for Southcentral, due to the subtle differences in the evolution
of the impulses of energy, uncertainty remains as to exactly
where the highest snowfall amounts will be.

Farther west, the Storm force low south of the western Aleutians
moves northwest today. Models show multiple low pressure systems
developing over the North Pacific, south of the western and
central Aleutians, each moving north then northwest, due to the
blocking high over the Bering.

&&

.AVIATION...
PANC...Predominantly MVFR conditions expected through the TAF
period, although conditions will drop to IFR during periods of
heavier snow. Due to the weather pattern, it is difficult to
pin point the periods of heavier snow. Conditions will begin to
improve late this evening.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...

Upper level North Pacific low moving northward is overspreading
precipitation across Southcentral Alaska. The associated inverted
trough is producing gusty winds through Thompson Pass as well as
down Cook Inlet (mainly western Kenai). Snow and blowing snow is
a resultant concern for both of these areas through tomorrow
morning. Heaviest snow through Thompson Pass is expected today
before tapering off and becoming light tonight. Winds will
continue to be gusty beyond Friday and any transportable snow may
create reduced visibilities at times. Western Kenai will see snow
and pockets of isolated blowing snow across the inland areas, but
the worst conditions will be near Cook Inlet, more specifically
from Nikiski to Anchor Point. Winter Weather Advisories have been
issued for both areas and will remain in effect until Friday
morning. A third Advisory is in effect for the Copper Basin, for
snow accumulations of 6-12 inches along the Richardson Highway
near Glennallen, as well as for blowing snow from Paxson north to
Isabel Pass.

A polar trough dives south across Southwest Alaska Thursday night
and Friday and will reinforce cold air across Southcentral.
Any forcing for precipitation across Anchorage, Kenai, and the
Mat-Su Valleys will be cut off by Friday as the low moves south
of the AKPen, but will allow for continued precipitation across
the North Gulf Coast (including eastern Kenai) into Saturday
morning.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3:
Today through Saturday)...

An upper level trough extends from the interior into Southwest
Alaska with a low pressure system over the Gulf. This system is
bringing some mid and high level clouds to parts of Bristol Bay
and the AKPen and some lower clouds over the Lower Kuskokwim
Valley. An upper low will develop over Bristol Bay tonight and
Friday as colder air reinforces the trough. This will bring
chances of light snow to eastern portions of Bristol Bay from
Iliamna to near King Salmon but very little accumulation is
expected. Cold air advection is expected to move across the area
tonight and Friday which will bring colder air and wind chills to
near -30 in some areas. Additionally, gusty winds will continue
out of the north. On Saturday the low pushes into the Gulf with
gusty winds continuing for the Kuskokwim Delta, but lighter winds
across Bristol Bay. Otherwise dry conditions expected on Saturday
with a few lingering clouds.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3:
Today through Saturday)...

A front will slowly move north across the western Aleutians
through tonight with Gales across the western Bering and western
Aleutians as well as areas of light rain. Meanwhile high pressure
will dominate the central portions of the Bering and Aleutians
through Saturday with low clouds expected. Out to the east over
the AKPen cold air will filter across the area on Friday and
Saturday and create gusty gap winds south of the AKPen with
pockets of storm force gusts out of the gaps up to 60 kts as well
as heavy freezing spray. Late Friday into Saturday another storm
force low will across the western Aleutians this low will track
northwest across the western Bering on Saturday, expect mainly
Gales but pockets of storm force winds possible near the low.

&&

.MARINE (Days 3 through 5 - Saturday through Monday)...

Gulf of Alaska:

A weakening low tracks across the Gulf through Monday. Forecast
confidence is good. Gusty Northwest gap winds expected through the
Barren Islands and near Sitkinak for Sunday. Gusty Westerly winds
spread across the Southern Gulf through Monday. An Easterly
Barrier Jet forms along the Alaska Peninsula into the Eastern
Aleutians for Monday.

Bering Sea/Aleutians:

A well developed Central Aleutian low moves to the Central
Kamchatka coast for Monday. Widespread gales from the Pribilofs
west through Monday, with areas of storm force winds near the
western Aleutians, diminishing Sunday. Seas building to 25 feet
Sunday over the Western Bering, subsiding Monday. Seas on the
Pacific side of the Aleutians to 20 feet, subsiding Sunday.

A North Pacific low approaches the Central Aleutians for Monday.
Forecast confidence is low, due to the low`s track and
development. Winds and Sea state are uncertain with this low.

&&

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

A quite interesting pattern is expected as multiple upper level
short-wave troughs advance through the forecast area for the long
term. Upper ridging from the North Pacific transiting from west
to east (eastern Bering through Southcentral) could create a
challenging forecast especially for P-type and snowfall amounts.
Rapid moving short-wave troughs aloft combined with CAA could
bring considerable snowfall amounts across Southwest and
Southcentral. Dry but cooler temperatures could likely linger over
Southcentral, but somewhat rising temperatures and increased
weather activity is possible over Southwest through Wednesday.
Stronger winds and elevated seas are expected over the
Bering/Aleutians, posing stronger gap winds for much of the
Aleutian Chain through Wed.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory 121 131 141.
MARINE...Gale Warning 119, 130, 138-139, 150, 155, 160, 175-178,
180, 185, 411-413.
Heavy Freezing Spray Warning 130, 138-139, 150, 160, 165,
179, 185, 412, 414.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...NR
SOUTHCENTRAL ALASKA...KM
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...RC
MARINE/LONG TERM...MK/CB

000
FXAK69 PAFG 271400
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
500 AM AKST Thu Jan 27 2022

.SYNOPSIS...

The most impactful weather over the next few days will be snow
today and tonight south and east of Fairbanks, with 3 to 7 inches
expected from Salcha to the Alcan Border. The heaviest amounts are
expected from Dot Lake to Northway and in the Eastern Alaska Range.
1 to 3 inches are expected from Denali Park to Fairbanks to Eagle
Summit. Northeast winds will also increase today and persist into
Saturday south of the Brooks Range with gusts to 45 mph along
with blowing and drifting snow expected over Steese and Elliot
Highway Summits, the White Mountains, and the Richardson Highway
south of Trims Camp. The West Coast will remain clear and cold and
the North Slope will see continued west winds of 15-25 mph with
light snow possible starting Saturday morning, along with cold
wind chills.

&&

.DISCUSSION...

Aloft...At 500 mb, troughing exists over the Mainland anchored by
a 524 dam upper level low in the Gulf of Alaska, while ridging
exists over the Bering Sea and western capes anchored by a 546 dam
high between St. Paul and St. Matthew Islands. A 482 dam closed
low also exists over the high Arctic. Troughing over the Mainland
will deepen heading into the weekend with the current low in the
Gulf of Alaska absorbing another low diving south off the Mainland
to form a 512 dam upper level low near 150 W by 3am Saturday.
Ridging over the Bering and West Coast will strengthen as the 546
dam high moves north to the Chukchi Peninsula at 544 dam by 3am
Saturday. The 482 dam closed low in the high Arctic will move to
the Canadian Archipelago by Sunday morning at 478 dam while the
high over the Chukchi Peninsula stays put and the low in the Gulf
slides east into southeast Alaska and the Yukon Territory through
Sunday.

Surface...Low pressure in the Gulf of Alaska and high pressure
over the Arctic Plain will persist through the short term forecast
period. This will set up a strong pressure gradient across the
state and allow for northeast winds to increase today and continue
into Saturday. A 984 mb low in the Gulf of Alaska will move north
to the Kenai Peninsula by Friday morning, then to Prince William
Sound by Saturday afternoon while slowly weakening. A 1038 mb high
over the Arctic Plain will weaken in place to 1029 mb by Sunday
morning.

Models...Models are not picking up a 50 to 150 mile wide band of
stratus and flurries from Crooked Creek to Manley Hot Springs to
Fort Yukon to Old Crow. While this should erode as the upper level
trough digs south and the wave of snow waves west today, we`ll
have to manually add it in to the forecast for the morning hours
today. Models are in good agreement at the surface and aloft
through the short term period, though there are some small
differences. The NAM has a much stronger upper level low in the
Gulf of Alaska than all other models by Saturday afternoon, and
subsequently colder temperatures aloft over the Central and
Eastern Interior. We will lean against the NAM for temperatures
at the end of the short term because of this and use a blend of
the other models to drop high temperatures a few degrees across
the forecast area the next couple of days. The NAM and the ECMWF
are more aggressive than the GFS with spreading light
precipitation to the Eastern North Slope on Saturday from front
from a low over the Canadian Archipelago. We will lean toward
this solution rather than the drier GFS solution, as west winds at
the surface and onshore flow aloft should favor this.

West Coast and Western Interior...Dry, clear, and cold conditions
are expected through Sunday. There is a slight chance areas from
McGrath to Nikolai and closer to the Alaska Range could see light
snow tonight, but otherwise skies are expected to remain clear.
Northeast winds from 10 to 25 mph from the Seward Peninsula south
will continue into Saturday, strongest in the Lower Yukon and
Yukon Delta. Highs temperatures in areas with wind will be in the
single digits above and below, while areas without wind can expect
highs in the teens below. Lows will be mostly in the teens below
with some 20s and 30s below near Kotzebue and into the Kobuk
Valley.

North Slope and Brooks Range...Skies will remain clear until a
front spreads clouds south on Friday afternoon. Flurries will
develop Saturday morning and persist through the weekend as
several more weak fronts drop south from the high Arctic. West
winds 15 to 25 mph will persist along the coast through the
weekend, and combined with current cold temperatures have
warranted Wind Chill Advisories from Nuiqsut east. NE winds 15 to
25 mph through Brooks Range Passes will also continue through the
weekend.

Central and Eastern Interior...Snow from Fairbanks south and east
today and tomorrow with the heaviest accumulations in the Eastern
Alaska Range (4-8") and from Delta Junction to Northway (4-6").
Lighter amounts of 1 to 3 inches are expected from Denali Park to
Fairbanks to Eagle Summit. Northeast winds will be increasing
today and continuing into Saturday. Summits and ridgetops in the
White Mountains and along the Elliott and Steese Highways can
expect gusts of 35 to 45 mph and areas of blowing and drifting
snow with low visibility. Areas along the Richardson Highway south
of Trims Camp can also expect gusts to 40 mph and significant
blowing and drifting snow. Expecting a wide range of temperatures
today from 20s below near Bettles to single digits and teens above
in the Alaska Range and near the Alcan Border. Clouds begin to
clear Friday night and temperatures are expected to drop in a
hurry with lows mainly in the 20s below by Sunday and 30s below by
Monday.

Extended Forecast For Day 4 Through 7...Pretty quiet weather is
expected through the middle of next week as a blocking high
persists over the Bering Sea. This will bring continued northerly
flow with dry conditions and colder temperatures.

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

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory for AKZ203-AKZ204.

Winter Weather Advisory for AKZ220-AKZ221-AKZ223-AKZ224-AKZ226.
&&

$$

CHRIEST JAN 22

000
FXAK67 PAJK 271428
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
528 AM AKST Thu Jan 27 2022

.SHORT TERM...A gale force low pressure system remains on track to
slowly move through the western Gulf bringing its associated
precipitation shield and fronts into Southeast Alaska through the
rest of the week. Forecast models remain in good agreement with
the timing and location of the precipitation, with most locations
seeing slightly warmer than normal temperatures and rainfall today
through Friday.

The main exceptions to the rain are the Haines and Klondike
highways at elevation near the Canadian border. Winter weather
advisories have been issued starting this afternoon through Friday
morning for these transportation corridors. Snowfall amounts are
expected to be high enough to cause at least an inconvenience if
travel is attempted during this timeframe. Elsewhere confidence
over rain/snow amounts is lowest near Hyder where cold air could
cause rain to precipitate out as snow, and highlights may become
necessary as the bulk of the precipitation impacts the Misty
Fjords area Friday into Saturday.

Current estimates for precipitation amounts with this system are
suggesting something closer to a 1 to 2 year return interval, so a
significant amount of moisture, but not as much moisture as last
Friday/Saturday`s event. Impacts are also expected to be less due
to the decreased precipitation amounts.

Winds will be strong enough for Small Craft Advisories for large
sections of the inner channels, along with Small Craft Advisories
and Gale Warnings for the outer coast through Saturday.


.LONG TERM.../Saturday into Thursday/...Precipitation will slowly
and progressively dissipate and move out of the region from north
to south through the period as the aforementioned Gale- force low
and associated front continue to weaken and drift southeastward,
remaining just off the Outer Coast.

Temperatures will cool starting on Saturday night as a ridge of
high pressure presents its influence behind the frontal system,
which will give way to a more northerly/continental flow over the
area. This is indicated via model forecast 850mb Cold Air
Advection and MOS guidance. Overall, temperatures should not dip
very much below seasonal averages for the area.

As for the winds, for Saturday morning, as the front passes, Gales
look to be over Dixon Entrance and near the ocean entrance of
Clarence Strait with small craft winds all the way up the strait.
Also, for Saturday morning, Small Craft winds look to be
around/near ocean entrances up the Panhandle and just off the
Outer Coast. After that, winds will progressively subside through
the period as the front and low continue to weaken and move past
the area. For Sunday afternoon, onward, a tightening north to
south pressure gradient, caused by a high pressure center poised
over the Canadian Yukon, looks to cause Small Craft winds over
the Lynn Canal area.

Beyond the weekend, a possible break from much of the precip may
be in store for the panhandle. Unfortunately, any such break will
likely not last very long as another system may arrive between
Tuesday and Wednesday. There may be a chance that some areas could
see accumulating snow from this system but this far out giving
details with any degree of confidence is problematic. Looking
ahead to temperatures, while an overall slight cool down in
temperatures is anticipated through much of next week, the chances
of a northerly outflow event have largely diminished.

Forecast confidence is generally average until mid Sunday morning,
which is when operational models began to diverge on the strength
and track of the aforementioned low/front as it begins to dip
southeastward. Therefore, for that point, onward,the forecast is
blended toward the NBM/WPC.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind from noon AKST today through late tonight for AKZ023.
Winter Weather Advisory from 3 PM this afternoon to 9 AM AKST
Friday for AKZ018-019.
MARINE...Gale Warning for PKZ042-043-051-052.
Small Craft Advisory for PKZ022-031>036-041-053.

&&

$$

Suk/JLC

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