Graphical Hydro Meteorological Discussion

705
FXAK68 PAFC 050240
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
540 PM AKST Thu Dec 4 2025

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

...Products Issued...

1) A Winter Weather Advisory is in effect for Anchorage and Eagle
River (all elevations), and the lower Matanuska Valley until 7AM
Friday for 1 to 3 inches of snow (higher amounts on the Anchorage
Hillside, Eagle River, and Palmer) and a glaze of ice.

2) A Winter Storm Watch has been issued for the northern Copper
Valley, northern Susitna Valley, and Tok Cutoff from 6PM Friday to
3AM Monday for possible blizzard conditions. Up to 3 inches of
snow for Mentasta Pass and wind gusts up to 50 mph.

3) A Winter Storm Watch has been issued for Thompson Pass from
6AM Friday to 6AM Sunday for possible blizzard conditions and 8 to
16 inches of snow. Winds could gust as high as 55 mph.

4) A Winter Weather Advisory has been issued for the Copper River
Basin from 5PM this afternoon to 5PM Saturday for 4 to 12 inches
of snow. The lowest totals will be west of Glennallen, and the
highest totals will be south and east of Glennallen.

...Arctic airmass moves in this weekend...

A pattern shift will bring significantly colder temperatures for
everyone. The most affected locations will be the northern Copper
Valley, northern Susitna Valley, and Tok Cutoff. Northerly winds
will pick up this weekend and gust as high as 50 mph. Wind chills
will drop to 15 to 25 degrees below zero Friday night, and falling
further to as low as 25 to 40 degrees below zero by Sunday.

...Discussion...

This afternoon, the pattern continues to remain showery in
nature. A mixed bag of precipitation today is now showing signs of
tapering off across the Cook Inlet region, though the radar has a
difficult time resolving really low level precipitation. Most of
what is falling now is freezing drizzle mixed with a few sleet
pellets, but as advertised in the Winter Weather Advisory for the
area, a changeover to snow will ensue this evening and overnight,
resulting in mostly light snowfall and a glaze of ice. The 00z
sounding from PANC shows that dynamic cooling is helping to cool
the column, which has caused a reduction in the warm nose, and
steeper lapse rates overall as somewhat colder air moves in aloft.
500 mb heights help explain why precipitation has diminished some
across the Cook Inlet areas; the Cook Inlet region currently sits
in a col, which represents a lack in forcing in meteorology.

A positively tilted arctic trough digging across the mainland
from the northwest nears the Cook Inlet region Friday morning.
Upper level forcing just downstream of the trough will help to
spin up a surface low southeast of Kodiak Island, which will
quickly make its way northeastward across the northern Gulf
towards Yakutat Friday morning. Weak surface troughing and the
upper trough will also work in tandem to give the Cook Inlet areas
light to moderate snowfall rates overnight, accumulating to 1 to
3 inches, with higher amounts for the Hillside and northward up
the Glenn Highway. Any snow will come to an end Friday morning as
the trough moves away from the region.

The Arctic front pushes through Southcentral on Friday with
temperatures rapidly falling from north to south as the Arctic
airmass works into the region. These temperatures will likely be
the coldest so far this cold season with many areas across
Southcentral seeing temperatures fall below zero. The Copper Basin
could see temperatures fall into the minus 20s and dangerous wind
chills of -30 to -35 degrees. Lastly, the Arctic airmass will
also result in strong north/south gap winds for the Alaska Range
and typical spots across the southern Southcentral.

Heading into the weekend, Arctic air will become further
entrenched across much of Southcentral as an Arctic trough drives
south into the Cook Inlet and western Alaska Range. The intrusion
of very cold temperatures into interior valleys will continue to
fuel very strong and gusty winds through north-south oriented
gaps, including out of the Mat Valley, Thompson Pass, and all the
major passes along the northern Alaska Range. Wind gusts could
peak as high as 45 to 60 mph across parts of the Mat Valley and
through Thompson Pass, and up to 40 mph through Broad Pass,
Isabel Pass and Mentasta Pass. These intense gap winds coupled
with plenty of transportable snow at pass level could lead to
significant blowing snow, including potential for ground blizzard
conditions along the northern mountain passes starting as early as
Friday and persisting well into Sunday. Thompson Pass is more
likely to see both falling snow and blowing snow as moisture near
a quasi-stationary low developing over the Gulf wraps northwest
around the digging upper low/trough shifting into the western
Gulf. Prolonged blizzard conditions are likely through Thompson
Pass starting by Friday night and likely persisting until at least
Sunday morning.

Meanwhile, light to moderate snowfall will also continue across
much of Prince William Sound and out across the Copper Basin as
multiple shortwaves pivot northwest into the region around the
deep Gulf low and trough setting up to the southwest. Temperatures
across the Copper Basin most notably will nosedive as Arctic air
continues to stream in from the north, dropping from the single
digits on Friday night down to the -10s to low -20s by Sunday.
Where we see the gusty winds, wind chill values will become even
colder, dropping to as low as -30 to -40 from Saturday into
Sunday.

Across the Mat Valley, Anchorage and greater Cook Inlet region,
the main story heading into the weekend will be the plunge into
below average temperatures and bitterly cold wind chills, where
conditions will stay mostly dry but still quite windy in some
spots through Sunday. Air temperatures will drop from the 10s and
20s above late Friday down to around 0 to 10 above by Sunday, and
possibly colder for places protected from the gusty north winds.
Wind chill values will likely drop to around -10 to -20 over the
weekend as well, particularly where the winds are strongest across
the Mat Valley, west Anchorage and along much of the Cook Inlet.
Stay tuned to the forecast for updates as well follow this major
pattern change over the next several days.

-AM/PP/AS

&&


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

The low that has brought much active weather to Southwest Alaska
continues to weaken. The Kuskokwim Delta has seen skies clear with
wind speeds remaining elevated. Bristol Bay continues to see some
lingering showers as moisture remains over the area. The
Dillingham region is seeing periods of freezing rain showers as
surface temperatures have cooled below freezing, but aloft
temperatures remain above freezing. Conditions are expected to
improve this evening as drier air filters into the region. A front
will push into the Western Aleutians, allowing for precipitation
and gusty winds, but it will be blocked in by a Siberia High that
is extending over the Bering.

On Friday, an Arctic trough will drop into Southwest Alaska,
causing winds to become northeasterly and plummeting temperatures.
By Friday night, temperatures will drop to the negatives in the
Kuskokwim Delta and the Lower Kuskokwim Valley while Bristol Bay
will drop to the single digits. The northeasterly winds will also
become gusty over and offshore of the Kuskokwim Delta. The weekend
has temperatures remaining in the negatives in the Kuskokwim
regions. The combination of these very cold temperatures and
gusty winds will allow for the potential for extreme freezing
spray from Nunivak Island to Cape Newenham starting Saturday and
lasting through Tuesday. Another potential threat is blowing snow
west of Bethel including Kipnuk as snow on the ground becomes
lofted from the gusty winds. As the colder air flows over the
warmer ocean in the Bering and with the upper trough, convective
snow showers will begin in the Alaska Peninsula and the Aleutians.
Gusty winds in these regions could blow this snow around and
reduce visibility through Tuesday. This cold air mass is expected
to persist through next week, so more impacts from the cold could
be seen.

-JAR

&&


.LONG TERM FORECAST (Days 4 through 7 - Monday through
Thursday)...

The long term outlook will favor below normal temperatures for
both Southwest and Southcentral Alaska from Monday into the latter
half of next week. An arctic airmass will spill into all of
interior Alaska and the the southern Bering over the weekend.
Below normal temperatures will change little as a trough over the
western Gulf of Alaska brings a North Pacific low close to the
northern Gulf Coast on Monday. This area of low pressure will stay
in place through the latter half of next week. Ultimately, very
cold temperatures across Alaska will result in strong gap winds
from Seward to the Copper River Delta. Northerly flow will bring
in renewed colder temperatures across the Kuskokwim Delta and
Bering Sea by the middle of next week. Precipitation chances will
be below normal due to the drier northerly flow into the state,
but occasional snow showers will be possible along the Gulf Coast.
Additional snow will be possible across the Eastern Aleutians and
Alaska Peninsula, where ocean effect snow chances will increase
through the period.

-BL

&&

.AVIATION...

PANC...A weak low pressure system is spinning in northern Cook
Inlet within a region of weak flow through the atmosphere. Thus,
ceilings have been allowed to lower to IFR with occasional BKN
LIFR conditions. Freezing rain and or freezing drizzle will
continue through the rest of the afternoon before a second round
of steadier precipitation moves across the terminal tonight. This
round should be predominantly snow along with MVFR to IFR
conditions. Snow becomes more confined to the Chugach
Range/Anchorage Hillside mid-Friday morning. VFR conditions look
to return late Friday morning to early afternoon as colder and
drier air moves in then.

&&


$$

416
FXAK69 PAFG 050043
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
343 PM AKST Thu Dec 4 2025

.SYNOPSIS...
Temperatures continue to drop across the region. Generally clear
and calm conditions expected through Friday with northeasterly
winds increasing late Friday into Saturday. Areas of blowing snow
and low wind chills are likely as winds increase. Winds decrease
Sunday into Monday, but cold temperatures remain well into next
week.

&&

.KEY WEATHER MESSAGES...
Central and Eastern Interior...
- Mostly clear and cold weather, temperatures dropping as low as
to 30s and 40s below zero by this weekend.
- Clouds will be around in the Eastern Interior, limiting how
cold temperatures get. Snow will also try to move in on
Saturday (1 inch or less) from Delta east to the AlCan Border.

- N/NE wind increases significantly on Saturday from the Yukon
Flats southwest. Gusts above 1000ft may be upwards of 30 to 50
mph whereas valleys can see gusts up to 30 mph (IF the inversion
breaks). This continues into Sunday AM, then weakens.
- Ambient temperatures through Sunday, with no clouds or wind,
will drop into the 20s and 30s below zero. A few colder spots,
especially north and east of Fairbanks may hit 40 below.
- Wind chill values may be as low as 60 below zero from Tanana
to the Yukon Flats this weekend. Significant blowing snow is
possible in the higher terrain above 1000ft.
- This could be a significant wind event and end up being
impactful as it could lead to tree damage and power outages.
- Blizzard conditions are possible Friday and Saturday along
the Parks Highway from Carlo Creek to Cantwell and from Trims
Camp to Fielding Lake along the Richardson Highway.

- The cold trend continues into next week. Winds weaken rapidly
late Sunday into Monday and clouds clear again. Strong
temperature inversions will form in Interior Valleys. The
coldest valleys will likely drop into the 40s and 50s below
zero.

West Coast and Western Interior...
- A cold trend continues through the weekend. Expect minimum
temperatures in the single digits above and below 0 along the
coast and in the teens to 30s below zero in the Interior
Valleys.

- North-northeast winds increase this weekend. Wind gusts may be
up to 35 to 45 mph along the coast and in the higher terrain.

- With temperatures below 0 and wind this strong, it could lead
to wind chills as low as -50F in some spots.

- Winter Storm Watches remain in effect for strong winds, blowing
snow, and very cold wind chills from Koyuk to Huslia and south
to the Yukon Delta from Friday night through Monday night.

North Slope and Brooks Range..
- A front moves west to east across the North Slope Thursday
through Friday. Light snow moves across the North Slope reaching
Deadhorse and the northern portions of the Eastern Brooks Range
Friday morning and diminishes Friday evening. Accumulations up
to 1 inch possible.

- Expect temps in the negative teens along the coast with 20s
below zero inland through tomorrow, then widespread temps in
the 30s below zero with some 40F below readings possible in the
coldest locations this weekend.

- Northerly winds increase Friday up to 10 to 15 mph along the
coast and up to 25 to 35 mph through Brooks Range passes. Wind
chills fall to as cold as -60F through the Brooks Range passes.

&&

.FORECAST ANALYSIS AND DISCUSSION...
For Thursday through Sunday.
At the start of the forecast period Thursday, the overall pattern
is dominated by 3 main features; a 555 decameter upper level high
in the northern Bering Sea, a 536 decameter upper level low over
the Alaska Peninsula, and a 500 decameter upper level low in the
high Arctic. The Bering Sea high moves north into Eastern Siberia
and the Arctic low moves south towards the Eastern Interior
through Friday. The Arctic low brings with it very cold
temperatures with 850mb temperatures near -30C. A very high
amplitude pattern develops between the high and low Friday
through Saturday, which peaks as the Arctic low gets pulled
southwest towards Kodiak Island and combines with the Alaskan
Peninsula low reaching 495 decameters by Saturday night. This
reinvigorates the weakening trough and further strengthens the
gradient between the high and the low which creates strong jet of
wind aloft across the Interior Saturday and Sunday.

Winds will increase through Friday at higher elevations and then
increase even further Saturday morning. The corridor where the
strongest winds are expected is from the Eastern Brooks Range and
Yukon Flats south and west towards the Yukon Delta. This
orientation places the strongest winds over the same locations
that saw recent snowfall earlier this week. Fresh snow greatly
increases the threat of blowing snow and some ground blizzards are
expected, especially along higher terrain in that same corridor.
Cold, dense, Arctic air sweeps across the Interior bringing our
850mb temperatures down into the -25C to -30C range by Saturday.
Clearer and calmer conditions across the Interior in the wake of
the snow earlier this week is allowing strong inversions to
develop in Interior valleys. These inversions are bringing low
temperatures well below 0, reaching into the -20s to -30s Thursday
and Friday. Saturday winds pick up enough to mix many of the
Inversions out of the valleys which will raise the temperatures
into the negative single digits and teens, but very cold wind
chills into the -30s to -50s become possible. Strong inversions as
expected are difficult to mix, but winds should be strong enough
to fully mix out the inversion for most valley locations north
and west of Fairbanks. The Middle and Upper Tanana Valleys will be
more sheltered from the strongest winds, but could still see some
strong gusts break through Saturday and Sunday.

&&

.EXTENDED FORECAST DAYS 4-7...
For Sunday night through next Thursday.
At the start of the extended forecast period, Sunday night, a high
amplitude pattern continues to weaken as the high and low
sustaining it both weaken. Winds across the Interior diminish
slowly Sunday and fade more quickly Monday becoming mostly calm
again by Tuesday. Cold temperatures aloft continue through the
Eastern Interior through Tuesday with clear and calm conditions
allowing very cold valley temperatures to develop as strong
temperature inversions build late Monday. A building ridge in the
Bering Sea Wednesday and Thursday will begin to chip away at
colder temperatures, however additional Arctic air moves south
into the Eastern Interior to keep the cold air around through the
end of the extended forecast period.

Coastal Hazard Potential Days 3 and 4...None


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Blizzard Warning for AKZ848-850.
Winter Storm Watch for AKZ824>826-828>830-851-852.
Blizzard Warning for AKZ832-834.
Cold Weather Advisory for AKZ833-838>847.
PK...Heavy Freezing Spray Warning for PKZ850.
Heavy Freezing Spray Warning for PKZ854.
&&

$$

265
FXAK67 PAJK 050214
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
514 PM AKST Thu Dec 4 2025

.SYNOPSIS...

Key Messages:
- Very light winds and weak onshore flow remain across the
panhandle tonight into tomorrow.

- Light mist with areas of fog are likely to continue across the
panhandle with due to weak onshore flow.

- Late week into next weekend, long range models are still
suggesting a weather pattern that has been known to produce
heavy snow. High uncertainty on timing and amounts, but details
are being watched closely.

&&

.SHORT TERM...Light mist and rain continue across the panhandle as
onshore flow continues. The southern panhandle is seeing more of a
break from this light precipitation, but in turn they are seeing
continued areas of fog, at times dense below 1 SM. Along with these
lowered visibilities and onshore conditions, winds will remain light
across the area through tomorrow afternoon. The only exception to
this will be over the southern gulf waters as a quick moving, weak
low moves east south of the panhandle. This low will bring slightly
increased winds across the southern gulf to around 15 to 20 kts late
tonight into early Friday. Light winds of 10 to 15 kts, and weak
onshore flow, returns late Friday morning before a larger system
arrives Saturday.

On Friday night winds will begin to increase as a low pressure
system pushes into the north central gulf. This low will quickly
increase precipitation rates across the northern panhandle and
spread into the panhandle. Along with increasing precipitation
rates, decreasing temperatures will transition precipitation to snow
starting along the northern panhandle. Confidence is high for a long
lived snow even starting this weekend lasting into early next week.
Snow initially starts late Friday night, but the heaviest amounts
arrive later Saturday into Sunday. See the long term forecast for
more details on the snow forecast timing and intensity.

.LONG TERM.../Saturday through Tuesday/...A pattern change going
into this weekend is still looking to bring cold temperatures,
heavy precipitation, and strong winds to the panhandle into early
next week. Confidence has improved for snow potential in Skagway
and Haines over the weekend, and even more for the northern
highways. A winter storm warning has been issued for these areas
over the weekend, and a watch has been issued for Yakutat. The
special weather statement was also continued for the NE gulf coast
and the Icy Strait Corridor.

A system sending a front into the panhandle overnight Friday is
still looking to stall in the northern gulf through the weekend,
funneling consistent moisture over the panhandle. This front will
bring moderate to heavy rain rates to the area, with around an
inch to an inch and a half of rain in 24 hours expected for a
majority of locations and persisting at similar rates through the
weekend. Though these rain amounts may seem typical for a 24 hour
period, the persistence at those rates lasting through the weekend
and into next week will be watched closely, especially at higher
elevations. A cold air mass aloft shifts into the Yukon and
continues to moves southward through the weekend. A tightening
pressure gradient over the northern panhandle will increase
outflow winds through the weekend, helping to funnel the colder
air south into the panhandle. Decreasing temperatures with ample
available moisture will increase the potential for heavy snowfall
in the northern panhandle, extending south through the weekend and
into next week. Highest confidence of snowfall remains in the N
Panhandle over the weekend. Forecast becomes more of a challenge
moving towards the Icy Strait Corridor, starting as rain and
transitioning into a mix by Sunday, limiting potentially
accumulations. Expecting a transition over to snow going into
Monday, though uncertainty remains as to how much available
moisture there will be, limiting appreciable amounts. As snow
level drops south following the colder temperatures, snow
potential will also move further south towards the corridor, and
the rain/snow mix will then follow into the central panhandle.
Stay tuned to the forecast moving into the weekend as details come
into clearer view regarding potential amounts and refined timing.

As the gale force low moves into the northern Gulf and a high
sets up to the north of the panhandle into this weekend, a tight
pressure gradient allowing for northerly flow begins to set up
over the northern panhandle into Lynn Canal. This cold air mass to
the north contributes to the colder temperature trend over the
weekend and into early next week, alongside bringing stronger
winds down Lynn Canal. These winds will begin to increase Saturday
into Sunday with northerly gales in northern Lynn Canal with 35
to 40 kt winds by Sunday afternoon as the gradient tightens over
the northern panhandle. These gale force winds will last into the
beginning of next week as the gradient remains. Winds will
increase in Skagway at this time, with 25 to 35 mph sustained
winds possible Sunday and Monday. A decent 850-750 mb inversion
setting up over Whitehorse to the northeast will allow for these
winds to impact Skagway not only from the strong pressure
gradient, but from a decent density difference, allowing for more
confidence at Skagway having elevated winds over this timeframe
with gusts reaching up to 40 to 50 mph at times. Other land areas
will see an increase in SE winds as the front moves through, with
diminished winds between the waves of precipitation that push
through this weekend into early next week. Overall the outflow
pattern over the northern panhandle is expected to last into
midweek, with more northerly winds and offshore flow beginning to
move southward to around Icy Strait Corridor Monday onwards. This
cold dry air will help to lessen the precipitation amounts across
the northern panhandle midweek into the end of the week when
looking ahead.

&&

.AVIATION.../Until 00Z Saturday/...As far as CIGs & VISs are
concerned, primarily, flight conditions in the MVFR/IFR category
range for the TAF period, dipping down into the LIFR range for
anywhere that receives any FG through the overnight hours. Toward
the latter part of the period, some areas, specifically the
southern half of the panhandle & NE Gulf Coast area may improve
to the MVFR/VFR category range. SFC winds look to remain on the
lighter side through the period for all of Southeast Alaska. LLWS
values will also continue to be benign for the region through the
period.

&&

.MARINE...
Outside Waters: Calmer conditions tonight into tomorrow last over
the Gulf as a weak high remains over the area, before being
pushed out by the oncoming system moving in from the west by
tomorrow night. This next system will bring southwesterly to
southerly fresh to strong breezes (17 to 27 kt) across the Gulf
tomorrow night and becoming more southerly by Saturday. As the
pressure gradient tightens between the low in the Gulf and the
high to the north over Canada Saturday night into Sunday,
northeasterly near gale to gale force (30 to 40 kt) offshore winds
and gap winds will occur along the NE Gulf Coast between Yakutat
Bay and Cape Spencer. The southeastern Gulf will also see an
increase from near gales to gales (28 to 36 kt) as a front moves
through Saturday night into Sunday morning and again Sunday night
into Monday. Seas between 5 and 8 ft tonight will quickly increase
tomorrow night into Saturday as the system moves in to between 10
and 14 ft. The seas will continue to see an increase into Sunday
to 12 to 16 ft. Southwesterly swell continues tonight through the
weekend.

Inner Channels: Predominantly calmer winds tonight and tomorrow
anticipated to see a sharp increase Friday night into Saturday as
the next system moves into the area. This will bring southeasterly
winds across the inner channels between a moderate to fresh
breeze into Saturday, and up to a strong breeze (22 to 27 kt) for
northern Lynn, Frederick Sound, Stephens Passage, and near the
ocean entrances. The channels will see a brief increase as the
fronts move across the panhandle this weekend into early next
week. Northerly outflow begins to set up over northern Lynn Sunday
as the pressure gradient begins to tighten, bringing near gales
in the morning becoming gales into the day Sunday. Largely
expecting between 35 and 43 kt winds down Lynn Canal lasting from
Sunday into early next week, with the stronger northerlies moving
southward down to Point Couverden Sunday night into Monday. This
will allow some lower level convergence right around Point
Couverden from the southeasterly winds up Chatham Strait and the
northerly outflow coming down out of Lynn Canal, bringing winds
around Rocky Island to around 25 to 30 kt. Frederick Sound near
Point Fanshaw and up along Stephens Passage will continue to see
strong breezes to near gales throughout the weekend, alongside
Clarence Strait seeing near gales as the fronts move through and
bring stronger southeasterly winds.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Storm Watch from late Friday night through late Saturday
night for AKZ317.
Winter Storm Warning from 10 PM Friday to 3 PM AKST Sunday for
AKZ318.
Winter Storm Warning from 3 AM Saturday to 3 PM AKST Sunday for
AKZ319.
Dense Fog Advisory until 3 AM AKST Friday for AKZ330-332.
MARINE...Small Craft Advisory for PKZ661.

&&

$$

SHORT TERM...EAB
LONG TERM...ZTK/Contino
AVIATION...JLC
MARINE...Contino

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