Graphical Hydro Meteorological Discussion

797
FXAK68 PAFC 051440
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
540 AM AKST Fri Dec 5 2025

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

Key Points:

- A Blizzard Warning has been issued for Thompson Pass from 6AM this
morning to 6AM Sunday for possible blizzard conditions and 8 to 16
inches of snow. Winds could gust as high as 55 mph.

- A Winter Storm Watch remains in effect for the northern Copper
Valley, northern Susitna Valley, and Tok Cutoff from 6PM Friday to
3AM Monday for possible blizzard conditions.

- A Winter Weather Advisory remains in effect 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.

Discussion:

Our well advertised arctic airmass is quickly pushing southwards
through western and northern Southcentral this morning, as the upper
trough digs southwards across western Southcentral. Temperatures
have been steadily falling from north to south across these areas
with most locations having dropped into the single digits to teens.
Skies have also cleared across these areas, though some low stratus
and/or fog is lingering in some of the typical foggy valleys. Snow
has moved out of the Mat Valley and Anchorage bowl this morning
allowing the Winter Weather Advisory to be cancelled. The band of
snow showers is now pushing south and east across the Kenai
Peninsula as the trough approaches.

Snow remains ongoing across the central and southern Copper Basin
this morning where a Winter Weather Advisory remains in effect.
Highest snowfall amounts will be across the southern Copper Basin
and Thompson Pass areas. The arctic airmass will also surge into the
Copper Basin where temperatures will fall into the minus teens and
20s by Sunday morning and wind chills of -30 to -35 degrees given
persistent northerly winds. The strongest winds will be felt in the
typical north/south gaps where wind lofted snow will pose blowing
and drifting concerns, along with reductions in visibility. As such,
ground blizzard conditions are possible for the Alaska Range passes
beginning today and persisting through into Sunday. Blizzard
conditions are also possible for Thompson Pass where ongoing
accumulating snowfall and increasing winds through the pass will
lead to significant blowing and drifting of snow through at least
Sunday morning.

Across the Mat Valley, Anchorage and greater Cook Inlet region,
conditions will stay mostly dry, but will be cold and 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.

The aforementioned arctic trough will slow as it reaches the Gulf
Coast before deepening into a closed low over the northern Gulf this
weekend. This low will keep the coastal areas unsettled as
shortwaves rotate around the trough. With most areas along the coast
dropping into the 20s and lower 30s, several rounds of snow showers
can be expected through the weekend.

- PP

&&


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

Clearer and drier conditions are expected across most of Southwest
Alaska through this weekend along with continued cold
temperatures and gusty winds. Cold air will filter south across
the southern Alaska Peninsula, bringing rounds of snow showers and
gusty winds. This combination is expected to bring periods of
blowing snow along the Alaska Peninsula, primarily from Port
Heiden south. The Winter Weather Advisory remains in effect to
encapsulate this. 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. While precipitation
is expected to be nearly non-existant, gusty winds along the
Kuskokwim Delta coast may loft existing, transportable snow,
creating areas of blowing/drifting snow and reducing visibilities
at times. There is currently a Winter Storm Watch highlighting
these possibilities, as some uncertainty remains. This cold air
mass is expected to persist through next week, so more impacts
from the cold could be seen.

&&


.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...Early morning snow has moved eastward to the Chugach
Range/Anchorage Hillside. VFR conditions should persist through
the forecast period as colder, drier air moves in from the north.
Winds remain northerly around 10 kts, with gusts increasing to 20
kts after 00Z Saturday.

&&


$$

210
FXAK69 PAFG 051359
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
459 AM AKST Fri Dec 5 2025

.SYNOPSIS...
The cold trend continues today with temperatures dropping through
the day across all of Northern Alaska. This weekend we see a bit
of a mix up with strong wind developing from the White Mountains
to the Yukon Delta. Winter Weather hazards are issued across the
area for blowing snow, very cold wind chill and strong wintertime
wind. Winds decrease Sunday afternoon into Monday but the arctic
blast continues through next week.

&&

.KEY WEATHER MESSAGES...
Central and Eastern Interior...
- Cold everywhere with the coldest spots being in the valleys,
especially the Yukon Flats.

- Wind increases this weekend with significant blowing snow
possible in the Southern AK Range Passes, White Mtns and Dalton
Highway summits. Very cold wind chills expected for most of the
Interior as well.
- 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 PM, 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
expected 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 expected Friday night through Sunday
afternoon along the Parks Highway from Carlo Creek to Cantwell
and from Trims Camp to Fielding Lake along the Richardson
Highway. Through Sunday night along the Dalton/Steese Summits.

- Cold weather continues into next week with temperatures
dropping into the 40s and 50s below zero in the Central and
Eastern Interior Valleys.

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.

- Weakening winds prevail next week making for much colder air
temperatures. Potentially in the 30s/40s below zero in the
Interior and single digits/teens below zero along the coast.

North Slope and Brooks Range..
- Areas of light snow possible today as a front moves overhead,
especially from Deadhorse east and the Eastern Brooks Range.
Snow accumulations up to 1 inch.

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

- Northerly winds increase today 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...
The main story is the cold and wind coming this weekend. A strong
556 decameter high is over Eastern Siberia as a 501 decameter low
moves south along the eastern edge of the high. This evening, the
base of the trough on the eastern side of the ridge will be
positively tilted from northeast to southwest. As the energy from
the low gradually drops south, it will interact with energy at the
base of the trough. Tonight into tomorrow, the trough goes
negatively tilted and undergoes cyclogenesis in the Gulf. A 499
decameter low will be in the Northwestern Gulf with a 555
decameter high over Eastern Siberia. This results in strong
northeast flow across most of Northern Alaska. At the surface,
there will be gusty wind and temperatures below zero. We have
issued a plethora of hazards for blowing snow, cold wind chills
and high winds. These conditions will be most prominent from
Saturday morning into Sunday morning. Winds will gradually
decrease through the day on Sunday as the high weakens and the low
moves southeast/weakens.

Next week, winds will become mostly calm with very cold 850mb
temperatures around 20C to 30C below zero. This will likely
support temperatures in the 40s and maybe 50s below zero across
the Interior, while remaining in the single digits above and below
zero along the coast. No significant precipitation is expected in
the short term.

&&

.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...Cold Weather Advisory for AKZ809>811.
Blizzard Warning for AKZ848-850.
Blizzard Warning for AKZ851-852.
Winter Weather Advisory for AKZ824-829-830.
Blizzard Warning for AKZ832-834.
Cold Weather Advisory for AKZ833-838>847.
PK...Brisk Wind Advisory for PKZ801-853.
Brisk Wind Advisory for PKZ802>805-852.
Heavy Freezing Spray Warning for PKZ816-851.
Heavy Freezing Spray Warning for PKZ850.
&&

$$

Bianco

798
FXAK67 PAJK 050630 AAA
AFDAJK

Southeast Alaska Forecast Discussion...UPDATED
National Weather Service Juneau AK
930 PM AKST Thu Dec 4 2025

.Evening and 06z Aviation Update...Few updates to the marine and
general public forecast going forward. Westerly flow aloft is
causing enhanced leeside troughing near Haines and Skagway, with
gradients between Juneau and Skagway around a 1 to 2 mb
difference. This is generating up to 15 knot winds for Lynn Canal
from the south, but expecting to see the winds relax as the
westerlies aloft relax. These southerly winds have not stopped
Haines and Skagway from decoupling, however. Looking towards the
latest sounding in Whitehorse, it is clear that an inversion up to
5500 ft with moderately cold temperatures is causing some
katabatic flow, undercutting the southerly, more unstable air.
Therefore, kept Skagway and Haines north and west through the
night with up to 10 knot sustained winds.

&&

.AVIATION.../through Friday evening/
A mixed bag of flight conditions this evening with persistent
low clouds and isolated showers across the panhandle. Looking at
obs around the area, TAF sites range from isolated areas of VFR &
IFR to predominate MVFR & LIFR. Flight conditions are highly
variable hour by hour with CIGS bouncing between 200ft to 3500ft
and visbys between 1/2 SM to 4SM within fog, rain, or mist.
Through Thursday night flight conditions will generally remain the
same or continue to worsen slightly, continuing the trend of
bouncing between MVFR to LIFR flight conditions with CIGS AoB
2500ft and intermittent visbys as low as 1/4SM in fog. By Friday
mid-morning, brief break in precip for the area with general MVFR
flight conditions across along the northern panhandle. Best
flight conditions will be across the southern panhandle, along a
line from TAF sites Sitka to Petersburg and southward seeing the
greatest chances of VFR conditions by Friday afternoon.

Winds should remain around 10 kts or less overnight, going near
calm and variable at most TAF sites. Main exceptions are the
usual culprits of Haines and Skagway which will to see increased
winds up to 20kts as drainage flow winds continue through the
night. No LLWS concerns through the TAF period, however front
pushes into the NE Gulf by late Friday evening.

&&

.PREV DISCUSSION......ISSUED AT 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.

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 AKZ328-330-332.
MARINE...Small Craft Advisory for PKZ661.

&&

$$

UPDATE...NC
SHORT TERM...EAB
LONG TERM...ZTK
AVIATION...NM
MARINE...Contino

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