National Weather Service United States Department of Commerce


000
FXAK68 PAFC 270216
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
516 PM AKST Wed Jan 26 2022

.ANALYSIS AND UPPER LEVELS...
Today represents the relative lull in between two weather systems
across Southcentral. The system that moved through yesterday
bringing snow to much of the area moved quickly to the NE courtesy
of a 100+ jet at 300mb (30,000`). A transient ridge of high
pressure and the fresh snow helped to create some patchy fog this
morning across parts of the Mat-Su Valleys. The next system is
already moving quickly from the North Pacific towards the Gulf of
AK. Snow started early this morning for Kodiak Island where
several inches had accumulated by midday. Temperatures there were
hovering right around the freezing mark, so most of the snow was
quite wet and heavy. Snow started across the southern Kenai and
parts of the Copper River Basin early this afternoon as the
occluded front lifted north. The rest of inland population
centers saw dry and cloudy conditions.

Further to the west, a storm-force low moved into the Western
Aleutians overnight and this morning. Gusts in the mid-50 mph
range were observed over Shemya Air Station. This system peaked
this morning with the aid of a 85 kt jet at 300 mb. It is now
weakening as it drifts to the north. The rest of the Bering and
Southwest AK remain quiet under a dominant area of high pressure.

&&

.MODEL DISCUSSION...Models are in great agreement leading to
moderate to high forecast confidence in synoptic features. The
problematic areas of the forecast will be precipitation types at
Kodiak City and snowfall amounts through Friday morning. A
widespread, long duration will move over Southcentral starting
tonight and persisting into Friday morning. As moisture streams in
from the Gulf of AK, a trough of polar air will slide into SW AK.
While this is a favorable set-up for snow for Southcentral, due to
the subtle differences in the evolution of the pieces of energy,
uncertainty remains on exactly where the highest snowfall amounts
will be.

&&

.AVIATION...
PANC...VFR conditions and north winds will persist until snow
starts late tonight. As the snow moves in, expect conditions to
deteriorate in earnest around 13z. Timing could vary by +/- 2
hours. IFR cigs and vis will be likely as snow persists through
much of Thu.

&&

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

Light snow will continue tonight and gradually intensify through
the overnight hours. As an inverted trough cycles around the
North Pacific low, precipitation will spread north and west,
beginning with the Copper River Basin and then into Anchorage and
Western Kenai tonight and tomorrow. The inverted trough will
tighten pressure gradients as cold air is drawn south and thermal
gradients will increase as well near the Valdez/Thompson Pass
areas. This will produce blowing snow through Thompson Pass as a
result and a Winter Weather Advisory has been issued. Total snow
accumulations of 6 to 12 inches with winds occasionally gusting to
as high as 35 mph are possible in Thompson Pass. Winds will
generally increase through tonight with light snow beginning to
pick up through the overnight hours as it spreads north and east.
Snow and isolated pockets of blowing snow will be possible for
inland areas located on the western Kenai Peninsula. However, the
combination of winds gusting to 30 mph and falling snow, will
produce the worst conditions near the Cook Inlet. As a result, a
Winter Weather Advisory has been issued for the area. Falling snow
has already started across the Copper River Basin and will
persist into Friday morning. Snow accumulations are expected to be
between 6 to 12 inches. The highest accumulations will generally
be from Glennallen south. Meanwhile, north winds are expected to
increase from Paxson to Isabel Pass midday Thursday. Winds are
expected to gust as high as 35 mph which could reduce visibility
in blowing snow. Therefore, a Winter Weather Advisory has been
issued for this area as well. As with all blowing snow events,
visibility reductions are to be expected, as well as periods of
heavy snow and gusty winds.

Snow will continue to fall in Kodiak this evening then transition
to a rain/ rain snow mix late tonight due to warm air advection
from the Gulf. This pattern may persist with a back and forth
between rain and snow through the end of the week.

&&

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

Areas of low clouds and patchy fog extending across the Lower
Kuskokwim Valley and Kuskokwim Delta will linger through tonight.
By Thursday, an omega blocking pattern will be positioned over the
western Alaska region with the amplified ridge axis over the
eastern Bering Sea. Clear skies and colder conditions will prevail
for the Southwest mainland as the aforementioned ridge shifts
over the state. Daytime temperatures will range anywhere between
the single digits to the teens and overnight lows below zero.
Northeasterly winds will also increase from Thursday to Saturday
in response to a tightening pressure gradient between a North
Pacific low in the Gulf and the eastern Bering high. A combination
of gusty winds and cold temperatures will provide conditions
favorable for wind chills in the -20F to -30F, especially across
the Kuskokwim Delta and Kuskokwim Valley.

As the cold, Arctic airmass descends south of the mainland on
Friday, northwesterly winds will ramp up and funnel through the
gaps and passes along the southern AKPEN. Moisture associated with
the Gulf low may push north of Kodiak Island, bringing a chance
of snow into the Alaska/Aleutian Range. Some of the moisture may
even make its away for interior Bristol Bay and the AKPEN, though
little to no snow accumulations are expected. Snow will taper off
with winds subsiding by Saturday as the low weakens and the
thermal gradient relaxes, leaving benign conditions for the rest
of the weekend.

&&

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

Forecast remains on track with a deep North Pacific low
approaching the Western Bering/Aleutians this evening. The
associated front will bring widespread gales with storm force
gusts, rain/snow mix, and elevated seas above 20 ft into the
northern Bering Sea. With the exception of small craft winds, most
of the active weather will stay west of the Pribilof Islands and
Central Aleutians through Friday morning. Friday afternoon into
Saturday, a second North Pacific low will approach the southern
Bering Sea. Expect another round of gales and rain/snow mix
extending across the same regions. A cold, Arctic airmass moving
over the eastern Bering Sea will provide conditions favorable for
northwesterly winds to funnel through the gaps and passes in the
Eastern Aleutians from Friday through Saturday. This will also
contribute a return of heavy freezing spray for the offshore
marine zones and near the ice edge as well.

&&

.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
shortwave troughs advance through the forecast area for the long
term. Upper-level 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 shortwave troughs aloft combined with cold air
advection could bring considerable snowfall amounts across
Southwest and Southcentral. Dry but cooler temperatures could
likely linger over Southcentral, and somewhat rising temperatures
and increased weather activity 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 119 120 130 132 138 139 150 155 175-178 180
185 411-413.
Heavy Freezing Spray Warning 139 150 160 165 179 185 412.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...MSO
SOUTHCENTRAL ALASKA...NS
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MF
MARINE/LONG TERM...MK/CB


000
FXAK69 PAFG 262109
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
1209 PM AKST Wed Jan 26 2022

.SYNOPSIS...
Winter is back as a low in the Gulf and an arctic trough will
setup over the southern Mainland, bringing colder temps and
periods of blowing snow and snow to the Interior highlands and E
AK Range. Several inches of snow will fall southeast of Fairbanks
through Friday morning.

&&

.DISCUSSION...

Upper Level and Analysis...
There is a 489 dam arctic low anchoring the upper flow pattern,
with the center over the high arctic several hundred miles north
of Point Barrow. The trough axis extends all the way through the
Alaska Mainland with several weak shortwave troughs embedded
within the larger scale flow. The upper trough is hanging up over
the Southwest Interior and along the Western Alaska Range. Another
big feature is a Gulf of Alaska low spreading a rather moist warm
frontal zone north to Prince William Sound. This front will be the
main snow maker as we head into the future.

Model Discussion...
The models are mostly locked in to the snow, but there is still
some discrepancy on the northern end of the snow band, more
likely related to possible downslope flow off the White Mountains
into the Tanana Valley. The hi-res models are a bit drier, while
the ECMWF is wetter. For now will favor a middle ground NAM/GFS
blend, which pretty much makes no changes to the inherited
forecast, bringing light snow into Fairbanks, and heavier snow of
3-7" farther south and east.

Central and Eastern Interior...
Snow returns to the southeast Interior tonight, and will spread
northwest to Fairbanks by Thursday night. Expect amounts as high
as 3-7" from North way to Salcha, with much less toward Fairbanks.
North winds through Isabel Pass will likely result in a
combination of blowing and drifting snowfall. A tightening
northeast pressure gradient will allow for moderate 30-35 mph
gusts across the White Mountains and Sawtooth Mountains so expect
blowing/drifting concerns along the Elliott and parts of the
Dalton Highway. Snow ends Fri with some blowing and drifting snow
likely into the weekend.

West Coast and Western Interior...
A few flurries will persist into early evening over the Lower
Yukon and Middle Kusko, otherwise dry for the foreseeable future.
Northeast winds increase especially along the southern coasts,
with some marginal wind chill conditions as low as -40 F.

North Slope and Brooks Range...
Blowing snow continues along the eastern Arctic Coast but will
finally wane tonight as the west gradient slackens enough. Broad
northwest flow will persist hereafter and will keep enough energy
aloft to support some periodic snow showers/flurries along with a
15-20 mph west wind.

Extended Forecast Days 4-7...
Blocking over the Bering Sea looks to keep some form of
suppressive northerly flow over the Mainland which means high
likelihood of dry and colder, with possible snow shots across the
AK Range and North Slope. Overall it looks quite quiet with little
change in the pattern through midweek.

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

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

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

Brisk Wind Advisory for PKZ245.
&&

$$

AHSENMACHER JAN 22


000
FXAK67 PAJK 270056
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
356 PM AKST Wed Jan 26 2022

.SHORT TERM.../Through Saturday morning/ Another period of active
weather is in the forecast for Southeast Alaska as multiple
fronts and waves rotate around a parent low in the western Gulf.

The short term starts out with low clouds and fog blanketing much
of Southeast Alaska. MDCRS Soundings Wednesday afternoon from
both PAKT and PAJN show a strong inversion around 1,800 feet;
which has been responsible for keeping the low clouds and fog
around. Weak shortwaves moving overhead have also provided just
enough lift to squeeze out some drizzle across the area so have
added that to the forecast for this evening. Not expecting dense
fog like last night; but patchy fog should remain around the
region through tonight.

The main weather maker for the rest of the week approaches very
early Thursday morning. Current satellite imagery shows the low
approaching the SW gulf with a warm front extending NE towards SE
AK and a cold front stretching southward into the N Pacific.
Guidance suggests the low will move northward into the NW Gulf
then occlude and remain around that region through at least
Saturday morning. As the low sits and spins, multiple fronts and
waves will rotate into the Panhandle increasing rainfall rates and
coverage.

For Thursday, expect the warm front to weaken and dissipate as
the cold front to the west occludes and overruns it. The occluding
gale force front approaches the Outer Coast by Thursday afternoon
and pushes through by Thursday night. Expect low end Gales along
the Outer Coast and small craft conditions to develop through the
Inner Channels as the front pushes through. Steadier, heavier
rain arrives from west to east on Thursday then becomes more
showery in nature behind the front. There is a slight chance
precipitation could start as a brief period of snow for Yakutat
and Upper Lynn Canal before a changeover to rain. Expect snow for
the highways before snow levels rise near or above pass levels on
Friday. Overall, nothing out of the ordinary for this time of
year.

The second, stronger wave moves northward through the eastern
gulf Friday afternoon through Saturday morning increasing winds
and rainfall rates once again. Gale force conditions redevelop for
the eastern Gulf and move up the coast Friday night. Depending on
how close this wave tracks to the coast, strong wind gusts and
Gales may need to be added to the Inner Channels and SE Gulf
Coastal communities. Heaviest rain will spread from S to N across
the area during this time frame. Expect 48 hour rainfall totals
from Thursday afternoon to Saturday afternoon around 2 to 4 inches
for much of Southeast Alaska with the highest totals along the NE
Gulf Coast and along steep terrain. These totals agree well with
what ensemble guidance has for the area, so confidence is high
regarding the rainfall threat in the short term.

.LONG TERM.../Saturday into Monday morning/...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.

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, we blended
toward the NBM/WPC.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale Warning for PKZ042-043-051-052.
Small Craft Advisory for PKZ022-032>036-041-053.

&&

$$

CM/JLC

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