Graphical Hydro Meteorological Discussion

166
FXAK68 PAFC 091427
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
527 AM AKST Tue Dec 9 2025

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

Key Messages:

The forecast remains on track as the weather gradually becomes
less active today. The primary concerns continue to be for strong
winds and dangerously low wind chills. Temperatures will become
even colder through the week as a second cold air mass descends
into Southcentral.

Active Warnings and Advisories:

A Cold Weather Advisory remains in effect for the Copper River
Basin until 4PM for very cold wind chills as low as 40 to 50
below.

Discussion:

Although gusty winds through the typical north-south terrain gaps
(the mountain valley passes and coast) will likely continue, the
wind speeds are expected to diminish today into Wednesday morning
as the upper trough moves into the eastern Gulf. The next upper
level shortwave trough arrives into Southcentral Wednesday
morning. Most locations will see a return to breezy conditions,
increasing gradually for Wednesday afternoon. It won`t be until
the overnight into Thursday morning when the strongest surge of
winds would return. The trough exits east Thursday night and high
pressure begins to build in from west to east. Winds begin to
decrease again for Friday.

Temperatures will continue to remain cold for the rest of this
week. Though the risk of wind chill diminishes, ambient
temperatures will still be dangerously cold, thus similar cold
weather risks will remain. This cold is not showing any signs of
ending with this pattern remaining for the foreseeable future.
However, model agreement decreases along with forecast confidence
going into Friday as another trough dips into Southcentral. This
could bring snow to the higher elevations along the Alaska Range
and the Wrangell mountains. Breezy north appear likely to continue
through the rest of this week and weekend.

&&


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

Cold temperatures and dry conditions will continue across the
Southwestern Mainland through much of this week. Although winds
have relaxed across Southwest Alaska, cold wind chills of 20 to 30
below zero will be commonplace this week as the cold airmass is
in firm control. The coldest of the apparent temperatures will be
felt during nighttime and early mornings. A shortwave dropping in
from the north may clip northern portions of the Kuskokwim Valley
Thursday night into Friday morning bringing very light snow to the
area, while relatively warmer air across the Bering Sea pushes
into Southwest Alaska to provide a brief respite from the bitterly
cold temperatures.

The next front/low combinations enter the western Bering this
afternoon into Wednesday morning, bringing a round of rainfall and
potentially some gale-force winds to the Western Aleutians.
Models are in fairly good agreement on the idea that the system
remains mainly confined to the Western Aleutians and the western
Bering as the strong upper level ridge remains centered over the
Aleutian Chain through midweek.

&&


.LONG TERM FORECAST (Days 4 through 7: Friday through Monday)...

The long term starts out with a deep blocking high over the Bering
Sea that will amplify as a strong upper level shortwave and arctic
airmass drops south over the state. This will lead to more of the
same conditions for the southern Mainland with potential for high
winds out of all of the north-south oriented mountain passes and
coastal gaps from the AKPen east into Southcentral. The main
weather threat will be cold wind chills and ambient temperatures
in addition to the strong winds. Virtually the entire forecast
area will remain dry (possibly for a few more weeks), but some
light snow is possible along the northern faces of the Alaska
Range, Chugach and Kodiak Island. Some forecast guidance indicates
the surface low(s) may retrograde back towards the east on
Monday, which would bring some light snow, but overall forecast
confidence in this feature is low and the probabilities of this
are lower. Most things point to continued cold and breezy, with
areas of high winds possible.

-CJ

&&

.AVIATION...

PANC...VFR conditions with gusty northerly winds continuing on the
west side of Anchorage through early this morning. Winds expected
to diminish significantly by the late morning. Winds decrease
significantly going eastward, such that there may be a noticeable
difference in speed on the west side of the terminal vs. east side
at times. By noon, winds will be light out of the north, and
remain so through Wednesday.

&&


$$

534
FXAK69 PAFG 091348
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
448 AM AKST Tue Dec 9 2025

.SYNOPSIS...
Cold weather continues across Interior Alaska, with most such
areas in the negative teens or colder, and the Upper Tanana Valley
around -50F. The North Slope by contrast is in the single digits
and teens above zero as a round of light snow shifts eastward
across the area through Wednesday morning. Thereafter, colder air
moves in behind a cold front, dropping much of the North Slope too
into the negative teens. This will quickly change from Thursday
through the weekend as a low off Siberia shifts east and brings
increased cloud cover, widespread snowfall of at least an inch,
and much warmer temperatures to Alaska north of the AK Range. On
the North Slope, winds will also rise, which could result in
blowing snow and reduced visibilities at times, especially where
they combine with falling snow. Moving into next week, very cold
conditions could drop temperatures into the -40s or -50s F in
much of Eastern Alaska, even outside typical cold spots.

&&

.KEY WEATHER MESSAGES...
Central and Eastern Interior...
- Cold weather will continue across the Interior through
Wednesday. Cold valley locations will see lows in the -30s and
-40s, with the Upper Tanana Valley falling to around -50.

- Beginning on Thursday, another system will move into the area
and yield snow totals widely of around 1 to 3 inches through the
weekend, with higher totals of over 4 inches possible from the
north slopes of the Western AK Range to the White Mountains.

- Considerably warmer temperatures are likely on Friday with this
system, with highs widely rising into the positive single or
double digits.

West Coast and Western Interior...
- Cold weather with lows in the negative teens and 20s will
continue through Wednesday night ahead of the next system.

- From Thursday through the weekend, much warmer temperatures
with increasing clouds and 1-4 inches of light snow will be
brought in as the next system moves into the area.

North Slope and Brooks Range...
- Light snow will continue across the eastern North Slope through
Wednesday before colder air is ushered in by a cold front in
its wake. Accumulations will generally be light.

- A more robust wave of snow is expected from Thursday into the
weekend as a low moves along the Arctic coast. 2 to 4 inches of
snow are widely possible across the area. Higher totals are
possible in the Brooks Range and Arctic plains, mostly east of
the Dalton Highway.

- As the low moves along the coast, widespread winds of 25 to 35
mph, with higher gusts, will shift from SW to W and could
combine with falling/fresh snow to blow and reduce visibilities.

&&

.FORECAST ANALYSIS AND DISCUSSION...
A positively-tilted ~550 dm ridge at 500 mb is currently focused
over the Bering Sea. A broad area of troughing is extending from a
height minimum of ~497 dm over the Canadian Archipelago southeast
toward Nunavut, then southwest into Yukon. Temperatures at the 850
mb level are in the mid -20s C over the eastern Fortymile Country
and the Upper Tanana Valley, where surface temps are near -50F.
Moving through today and tomorrow, a cold front shifting southeast
across the North Slope will continue to bring up to a couple
inches of light snow to those areas before ushering in a return of
temperatures in the negative teens in its wake.

Otherwise, cold weather is expected across Northern Alaska until
the next system moves off of Siberia in the form of an upper 990s
mb surface low on Thursday. The low, which is expected to track
along the Arctic coast, will bring elevated sustained winds of
around 25-35 mph (with higher gusts) to the North Slope as it
transits east. It will initially bring snow to Western Alaska
Thursday morning, spreading east into the Central Interior / North
Slope by Thursday evening and reaching the eastern border by
early Friday morning. While there is some uncertainty on
accumulations through the weekend, across the Interior, many/most
areas could see at least 1-3 inches of accumulation, with a narrow
band of up to 4-6 inches extending from the northern slopes of
the Western AK Range northeast to the White Mountains. On the
North Slope, totals could widely reach 2-4 inches, with 6+
possible in the Eastern Brooks Range and parts of the Arctic
plains just east of the Dalton Highway. Given the amount of
snow/snowfall rates and the potential for falling snow to combine
with elevated winds, there will be the potential for visibility-
limiting blowing snow at times across the Arctic coast. Snow
totals of around 4 inches will also be possible on the Chukchi Sea
and southern Seward Peninsula coasts.

&&

.EXTENDED FORECAST DAYS 4-7...
After the low exits the area on Saturday, most snow will end
across Western and Interior Alaska with the exception of some
patchy light snow Saturday evening across parts of Western Alaska
as a weak low transits south along the coast. The North Slope by
contrast could see repeated periods of light snow into next week as
weak surface lows / upper-level shortwaves move along the coast.
In the Interior, cold air will reconsolidate, with widespread lows
down into at least the -30s and -40s F in the Central and Eastern
Interior and the negative teens in the Western Interior. Early
next week, models depict a strong ridge over the Bering Sea and
Siberia with extensive and very cold troughing over northwestern
Canada. With a large, dry, and very cold air mass aloft from
Mon Dec 15 through at least Wed Dec 17, -50s F are not out of the
question for much of the Eastern Interior and eastern North Slope
even outside of just the typical cold spots. The western extent of
this cold air is still an open question, but there is a chance it
could extend into the Central Interior/North Slope if the ridge
is farther west. Beyond then, there are model disagreements on
how persistent the airmass is.

Coastal Hazard Potential Days 3 and 4...None

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...None.
PK...Heavy Freezing Spray Warning for PKZ817.
&&

$$

DS

355
FXAK67 PAJK 091403
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
503 AM AKST Tue Dec 9 2025

.SHORT TERM...While clearing skies, dry weather, and colder
temperatures continue to spread across the northern half of SE AK,
the southern panhandle remains under the gauntlet as at least two
systems (one for Tuesday and one for Wednesday) are set to bring
rain and accumulating snow. While confidence is high in the
possibility of accumulating snow, confidence in snow totals is
somewhat lower for places like Ketchikan and Metlakatla, as
temperatures look to remain increasingly marginal through much of
Tuesday.

In the north, katabatic cold air outflow will be strengthened on
Tuesday as another low passes to the south, sending temperatures
even lower. Cold weather advisories are in place for parts of the
Icy Strait Corridor and Haines, where wind chills of -15 to -25F
are expected through much of Tuesday; the cold weather will be
particularly noticeable in the far northern panhandle, where wind
chills as low as -50F are expected through Tuesday night.

Further south, the eastern flank of a positively tilted trough
continues to send system after system into the panhandle. However,
confidence in the impacts of the upcoming Tuesday system have
diminished. Although confidence remains high in the development
of a strengthening shortwave trough which will move across the
south, the latest operational runs have indicated the potential
for the system to be somewhat stronger than previously forecast.
This scenario, if it verifies would enable the warm frontal
component of the system to be more successful in (temporarily),
pushing back the arctic boundary, sending snow levels rising back
above 2000 feet across locations like Ketchikan and Metlakatla,
and significantly curtailing potential snow totals. At this time,
given the relative degree of uncertainty of the full strength of
the anticipated WAA push up Clarence Strait, have decided to
retain the Winter Storm Warnings for Annette Island and the
Ketchikan area, but anticipate a greater chance of snow
accumulations being highly variable. As mentioned in previous,
the best chances of significant snow accumulation will remain in
areas more exposed to NE flow (and somewhat shielded from
southerly flow), like South Tongass and North Tongass, alongside
the Ferry Terminal N of Metlakatla. Other locations, like downtown
Ketchikan and Metlakatla themselves however, could potentially see
significantly less snow, with most precip falling as a rain snow
mix. Confidence is higher in the eastern side of PoW remaining
more snow than rain, and thus seeing greater snow totals. More
modest snow accumulations are likely for areas like Petersburg
and Wrangell, depending on how far north the system manages to
advance before being eroded away by cold air outflow. Temperatures
will cool across the southern panhandle through Tuesday night in
the wake of the system, and areas of the southern panhandle that
had been rain to this point may see an inch or two of snow
accumulation as the NW quadrant of the system moves overhead.

.LONG TERM.../Wednesday through Sunday/...Very little changes
made in the long term forecast as the arctic boundary that pushed
down into the panhandle over the weekend continues to march
southward through midweek. Wednesday a quick moving low will
finish dropping snow in the southern panhandle before moving
inland over British Columbia and ushering in a cold dry second
half of the week. Building high pressure in NW Canada and
interior Alaska supported by a deep arctic trough in the upper
levels is creating offshore flow and ushering colder continental
air through the northern panhandle. This air is very cold with 850
mb temps plummeting into the -15 to -25 C range by mid week
across the northern panhandle and near -10 C over the south. At
sea level this will translate to overnight lows ranging from
single digits above or below zero for the north to teens and 20s
for the south.

Daytime highs will struggle to reach the 20s for the north and into
the 30s for the south as we progress through the week. Coldest
temperatures look to occur Monday night through Wednesday night, but
sub freezing temperatures are likely to stick around into next
weekend. The panhandle from Icy Strait northward will be watched
as many locations will approach their criteria for cold weather
advisories or extreme cold warnings (especially the Haines and
Klondike Highways) through at least mid week. As of this forecast
discussion, an extreme cold warning for Skagway, primarily along
the Klondike Highway, was extended through noon Wednesday for
extremely cold temperatures as low as 45 degrees below.

Strong outflow winds of at least gale force will be blowing along
many northern panhandle channels through most of the week. A
strong 1035 mb high in the Yukon is the main driver of this
outflow and it will persist and strengthen to 1050 mb by late next
week. Expect gusty winds out of many of the outflow areas in the
northern panhandle to start with, but expect outflow out of areas
farther south through the week as the Yukon high spreads into
northern British Columbia by late week. Gaps along the NE gulf
coast will serve as outlets for strong winds as well through the
period. Aside from the above mentioned hazardously cold
temperatures, freezing spray will become a more widespread
problem for many marine areas in the inner channels and along the
NE gulf coast. The freezing spray could become heavy at times in
Lynn Canal, near Taku Inlet, and northern parts of Glacier Bay
throughout the week.

The continuing outflow will also keep most of the panhandle dry
through the mid and long range except for possibly the far south.
There is the possibility of a another snow event for the south
next weekend that is highly dependent upon an upper level ridge
moving over the panhandle at the start of the weekend followed by
another arctic trough replacing the one that dominates the state
for most of the week. One thing is for certain, winter has come to
southeast Alaska.

&&

.AVIATION.../Until 12Z Wednesday/...The northern half of the
panhandle will experience solid VFR conditions as that area will
remain under a dry & windy northerly outflow pattern. An area of
low pressure pushes into the southern panhandle, keeping them in
the MVFR/IFR flight category range through the 24-hour TAF period.
The lowest conditions will occur under areas of the heaviest
wintry precipitation. Conditions may temporarily lower to within the
LIFR category under the heaviest snowfall. The northeastern
panhandle from around PAJN & northward will receive the bulk of
the northerly outflow conditions & will remain windy at the
through the period. Centered aloft at around 1 to 2 kft, LLWS
values of around 25 kt in magnitude remain in store around the
PAJN area out of a generally northerly to northeasterly direction.

&&

Outside: Strong outflow winds continue to dominate the eastern
gulf coastal waters through Tuesday. Gale to storm force winds
with strong storm force gusts are blowing out of interior passes,
as well as any available drainage channel. Only a minor reduction
in strength is expected through Thursday, but winds are overall
expected to stay elevated through the week. Wave heights are
around 7 to 10 ft through the majority of the gulf, with areas
affected by the outflow winds seeing up to 15 ft waves persist
through the week. Freezing spray is possible with strong wind
gusts, mostly along the coastal waters. The central gulf is more
calm, only experiencing disorganized moderate breezes as the low
in the western gulf dissipates.

Inside: Strong gale to storm force outflow winds have persisted
through Monday and are expected to continue through the week. A
very strong pressure gradient in the northern panhandle is forcing
northerly storm force winds with gusts in the 60 kt range down
through Lynn Canal and Stephens Passage, as well as strong gale
force winds with storm force gusts out of Taku Inlet and through
the rest of the inner channels. Wave heights between 8 to 15 ft
are expected in areas of the strongest winds, with the rest of the
channels seeing around 6 ft or less and diminishing overnight.
Channel entrances and areas with greater localized forcing (like
Point Couverden) may see up to 15 ft waves at their peak. The
pressure gradient is expected to only slightly relax overnight,
continuing gale force outflow winds in Lynn Canal and Stephens
passage and strong breezes to near gale force winds for the rest
of the channels through the week.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Extreme Cold Warning until noon AKST Wednesday for AKZ318.
Cold Weather Advisory until 3 PM AKST Wednesday for AKZ319.
Cold Weather Advisory until noon AKST today for AKZ320-325.
Strong Wind until 6 AM AKST early this morning for AKZ325.
Winter Storm Warning from 9 AM this morning to midnight AKST
tonight for AKZ328-330-332.
Winter Weather Advisory from 9 AM this morning to 3 AM AKST
Wednesday for AKZ331.
MARINE...Heavy Freezing Spray Warning for PKZ011>013-031.
Heavy Freezing Spray Warning for PKZ021.
Heavy Freezing Spray Warning for PKZ021.
Heavy Freezing Spray Warning for PKZ032.
Gale Warning for PKZ011>013-022-031-033-053-642>644-651-662>664-
671.
Small Craft Advisory for PKZ021-032-034>036-641-652-661-672.

&&

$$

SHORT TERM...GFS/NC
LONG TERM...STJ
AVIATION...JLC
MARINE...GFS

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