Graphical Hydro Meteorological Discussion

770
FXAK68 PAFC 181251
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
451 AM AKDT Sat Oct 18 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA
(Days 1 through 3: This afternoon through Monday evening)...

An upper-level trough is currently stationary over the Copper
River Basin this morning. Situated at the base of this trough, a
compact vertically stacked low is spinning just north of Montague
Island. This feature, combined with lift and cold air advection in
association with the larger trough, is driving moisture across
the Sound northward into the western half of the Copper River
Basin. This moisture is wringing out in the form of snow across
the western and northern portions of the valley, with the heaviest
snow, on the order of 2 to 4 inches, falling along the Glenn
Highway west of Glennallen. Farther west, colder and drier air is
spilling south through the Susitna Valley. Lingering moisture
along the foothills of the Chugach and Talkeetna Mountains is
resulting in areas of fog and low stratus from Willow south to
East Anchorage.

The aforementioned compact low will move south through this
morning as the larger upper-level trough slides east toward the
Al-Can border. As it does, the snow will taper from east to west
across the southern Copper River Basin, but not before an expected
snowfall total of 2 to 6 inches, with the highest amounts around
Eureka. The combination of the low moving south, cold air
advection, and a ridge of high pressure building over the
interior, will drive gusty gap winds out of Seward, Whittier,
Thompson Pass, and the marine zone complex of Valdez.

While gusty northern gap winds through Thompson Pass and Valdez
Narrows persist into Monday, northerly surface flow should inhabit
really gusty conditions from getting into Whittier by Sunday. A
light easterly component is even possible for Passage
Canal/Whittier Sunday as the pressure gradient reorients. Whittier
winds and Passage Canal winds look to pick back up from the west
on Monday as a front lifts towards the Gulf Coast by then.

Speaking of the aforementioned front lifting towards the Gulf
Coast for Monday, the parent low pressure to this front continues
to trend more northward compared to previous model runs. As a
result, Kodiak Island will be wetter and windier Sunday night into
Monday with most of the heavy rain being confined to the Gulf
waters. Rain looks to also reach the Eastern Kenai Peninsula and
Western Prince William Sound Monday morning with rain perhaps
clipping portions of the northern Gulf Coast as well. The
strongest winds still look to remain on the southern flank of this
system in the North Pacific with some gale-force gusts over the
Gulf waters; however, easterly gales are also looking more likely
along the front as it lifts into the northern and western Gulf.
This system moves to the eastern Gulf and Southeast Alaska by
Monday evening. Stay tuned to further forecast updates as details
become more clear regarding this next frontal system for Sunday
and Monday.

-TM/DAN

&&


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

As of this morning, a surface trough is situated from northwest-
southeast across Unalaska and King Cove as a surface ridge slides
eastward across Southwest Alaska. A compact low looks to develop
within the trough envelope and bring showery and breezy weather to
the Pribilof Islands through this afternoon. Meanwhile, farther
west, weak transient ridging across Adak and Amchitka is eroding
away as a 1007 mb occluded low and its front move eastward and
away from the Western Aleutians.

The global models have trended a bit northward with the
advertised deep North Pacific low, which in turn will nudge and
bring easterly/northeasterly small craft and gale force winds
closer to Atka, Nikolski, and Unalaska for this evening into early
Sunday morning. If the current guidance holds / or keeps trending
northward, these winds will expand in coverage Sunday morning.
Likewise, confidence has increased that rainfall begins this
afternoon for these areas through Sunday morning as the northern
most portion of the low`s precipitation shield sideswipes the
Central and Eastern Aleutians.

With high pressure taking center stage across Southwest Alaska
Sunday morning, clearing skies and decreasing winds will allow for
some coastal and interior valley locations to bottom out in the
low to mid 20s for overnight lows. As the aforementioned surface
low tracks south of the area and deepens, its upper level low
component will amplify the 500 mb pattern, allowing for upper
level ridging to build in from the southeast. At the surface, cold
air advection from the light northerly to northwesterly flow
looks to be roughly on par with some of the coldest air so far
this season for the region. As the surface low tracks just south
of the Aleutians and Alaska Peninsula through Sunday
afternoon/evening, northwesterly winds in its wake will act to
reinforce cooler temperatures across Southwest Alaska.

Meanwhile, a secondary low pressure system works across the
Western Aleutians Sunday afternoon, bringing another round of rain
and windy conditions. As the low moves eastward towards Adak and
Atka, the global models have the system weakening and evolving
into a complex low as the 500 mb pattern becomes increasingly de-
amplified and flatter through Monday morning.

The latest runs of the GFS, EURO, and Canadian all show a potent
upper level wave and closed low drifting southward from the Bering
Strait and over Southwest Alaska Tuesday morning. There are
subtle differences in timing and placement of this feature, and
the GFS currently wants to develop a surface low Tuesday evening.
This will be one to watch for potential precip chances mid week.

-AM

&&


.LONG TERM FORECAST (Days 4 through 7)...

Upper level troughing over Mainland Alaska and a broad surface
low in the western Gulf of Alaska early this week will progress
into the eastern Gulf of Alaska through midweek. While relatively
good model agreement indicates most energy and associated rainfall
with this system will be directed towards southeast Alaska,
periods of rain can still be expected along the immediate coast
for the eastern Kenai Peninsula and Prince William Sound as
several weak perturbations rotate north into the northern Gulf
Coast. Eastward progression of this storm in the Gulf will promote
gusty northwesterly winds across the AKPen for Wednesday into
Thursday, with a cooler airmass spreading across the Bering and
much of the Mainland.

Guidance points to the jet stream becoming more zonal in the
North Pacific and in the Gulf of Alaska late in the week. Multiple
areas of weak low pressure across the Bering Sea, North Pacific,
northern Gulf of Alaska will keep much of the region under a
generally showery regime. Exact placement of these lows remains
uncertain and inconsistent, but confidence remains moderate that
the pattern remains rather progressive in the zonal flow.

&&

.AVIATION...

PANC...Predominantly VFR conditions and light northerly winds are
expected through the TAF period. There is a chance for a brief
period of MVFR conditions and patchy vicinity fog are possible
early this morning.


&&


$$

243
FXAK69 PAFG 182144
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
144 PM AKDT Sat Oct 18 2025

.SYNOPSIS...
A fairly benign weather pattern will remain in place across the
region for the remainder of the weekend and into next week as the
main storm tracks stays well to our south. There is a chance for a
few heavier snow showers in the Bering Strait region through
tonight while elsewhere occasional passing disturbances will
result in periods of light snow at times over the next several
days. Meanwhile temps will continue to cool slowly on a daily
basis.

&&

.KEY WEATHER MESSAGES...
Central and Eastern Interior...
- Periods of light snow and snow showers diminish in coverage
tonight and end Sunday morning.

- Dry and cooler Sunday and Monday with light snow possible along
the AlCan Border Monday night and Tuesday.

- Potential for more mainly light snow across the interior late
next week.

- Temperatures continue to gradually cool on a daily basis. Highs
are expected to be in the mid to upper 20s by the end of the
week.

West Coast and Western Interior...
- Snow showers will continue overnight through the Bering Strait
region. Uncertainty lies with how far east the snow gets. The
most likely outcome is it stays west of Nome and resides from
St. Lawrence Island to Teller west, though Nome may see some
lighter snow showers through tonight.

- Snow showers and squalls likely move over the same locations
through Monday morning before dissipating.

Snowfall totals through Monday:
- St. Lawrence Island - 4 to 8 inches.
- Teller to Wales - 1 to 4 inches.
- Nome - An inch or less.

- Temperatures gradually cool this weekend and next week by nearly
a degree per day. Highs are expected to be in the 20s to near 30
by the end of the week with the coldest readings in the
Interior.

North Slope and Brooks Range..
- Stratus with areas of fog continue with chances for light snow
through the weekend.

- Generally quiet weather persists for the foreseeable future.

- Colder next week with highs in the low to mid 20s along the
coast and teens/single digits in the Brooks Range. Lows will be
in the teens to near 20 along the coast and around 0 or below 0
in the Brooks Range beginning Monday.

&&

.FORECAST ANALYSIS AND DISCUSSION...
Broad troughing remains in place stretching from eastern Siberia
into central Alaska which in turn is allowing for a continued
cooling trend across the region. As disturbances meander through
the trough, we expect to see occasional snow showers in various
locations but most likely resulting in little to no notable
impacts. The most prominent disturbance at the present time is
tracking north through the Bering Strait and will continue to
produce some convective snow bands through the night and into
parts of Sunday. Elsehwere, it looks like some drying will take
place over much of the interior Sunday and into Monday.

Meanwhile a steady stream of surface lows continues to track
along the southern periphery of the trough as they trek from near
the Aleutians into the northern Gulf of Alaska. One such surface
low is expected to do just that and wind up near Yakutat by
Monday. This will likely send a weak frontal boundary north into
the eastern interior which in turn should bring another spell of
light snow showers to the eastern interior Monday night and
Tuesday. A similar pattern could develop later in the week as yet
another strong surface low enters the Gulf (more details on this
below in the extended discussion).

&&

.EXTENDED FORECAST DAYS 4-7...
As mentioned earlier the weather pattern for much of next week is
expected to be rather quiet with the most noticeable aspect being
the continued cooling trend. There will likely be a few light
snow showers developing in various parts of the region due to the
presence of the broad upper trough and associated embedded weak
disturbances. But certainly no notable hazards are expected as
the primary storm track remains to our south. There will be
another pair of surface lows entering the Gulf around midweek.
Models are having a tough time figuring out what they will do when
they get there. Past runs have suggested the potential for
additional energy moving north from these later in the week which
would mean an additional chance for interior snow. But even the
most aggressive solutions are indicating only light snow amounts
should that come to pass.

Coastal Hazard Potential Days 3 and 4...None

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...None.
PK...Small Craft Advisory for PKZ805.
Small Craft Advisory for PKZ806-854.
Small Craft Advisory for PKZ807.
Small Craft Advisory for PKZ816-850-851.
Small Craft Advisory for PKZ817.
Small Craft Advisory for PKZ853.
Small Craft Advisory for PKZ856.
Small Craft Advisory for PKZ857.
Heavy Freezing Spray Warning for PKZ859.
&&

$$

Laney

097
FXAK67 PAJK 182335
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
335 PM AKDT Sat Oct 18 2025

.SHORT TERM...Multiple gale force lows impact the region through
the week. Next system Sunday into Tuesday, a prominent low
Wednesday into Thursday, with another low Friday.

As the sun rose over the Gulf of Alaska Saturday morning,
northwest winds were ramping up to storm force along the southeast
gulf, southeast strong gales thru Dixon Entrance, and gales in
Clarence Strait. Strong to fresh breezes were prevalent across the
inner channels along with northerly winds in Lynn Canal being
pulled out by the low pressure. Moderate to heavy rain associated
with an occluding front were present as well, especially across
the central/southern Panhandle. Moving into Saturday evening,
expecting winds/rain to diminish with skies slightly clearing,
allowing fog to settle in across many protected areas. Sunday
winds by-and-large are near gentle to moderate breezes with the
exception of Clarence Strait, which could hold on to moderate to
fresh breezes out of the north.

Biggest change in the forecast is our next system moving into the
region Sunday night, with guidance trends indicating a much
stronger low; our forecast now indicating southeasterly upper end
gales to strong-gales for most of the coast developing by early
Monday morning, persisting through Tuesday.

.LONG TERM.../Tuesday through Friday/...
An active week is expected as multiple gale force systems move
into the gulf, bringing elevated winds, heavy rainfall, and snow
to the Klondike Highway. After Sunday/Monday`s storm, winds once
again increase Tuesday night to gales along the coast, with heavy
rainfall anticipated. For the most part 24 hour rainfall amounts
should be within seasonal normals. The southern panhandle is the
most likely to see the heaviest rain during this system on
Wednesday. While we have had some light snow impact the upper
elevations of White Pass, mid week will see snow levels drop
below 3000 ft, increasing the chances of accumulating snow
impacting the road system. Snowfall totals do not look overly
impressive relative to Alaska standards, likely less than 3-5
inches in 24 hours. This light snow, along with relatively warm
sub surface temps, should limit impacts.

Thursday looks to be a break in between systems, with another
system moving into the Gulf by Friday. At this time ensembles are
highlighting greater than 60 percent for gale force winds.

&&

.AVIATION...A showery environment continues over the panhandle
allowing for VFR conditions with times of lowered visibilities
and ceilings during heavier showers. These showers are very likely
to continue into tonight especially over the southern panhandle.
Conditions will then begin to improve tonight into tomorrow
morning from north to south. Yakutat has already seen clearing
conditions. Along with clearing skies, winds will weaken
throughout the night. This in turn allows for fog development. The
central to southern panhandle, near Petersburg and Wrangell, are
the most likely to see reduced visibilities below 2 SM beginning
early Sunday morning. Along with diminishing winds, they will
also become northerly as the low moves farther to the south of the
panhandle. The strongest winds will remain near Skagway and Haines
around 10 kts with gusts up to 20 kts at times.

&&

.MARINE...
Marines:Outside (Gulf/Coastal waters):
As of late Saturday morning, a gale force front was lifting
across the southern waters, with buoys reporting building
southeasterly seas and underlying southwest swell; significant
heights of 11 to 15 ft below 10 seconds. Winds decrease overnight
Saturday as the parent storm tracks towards Vancouver Island
bringing a brief respite. Sunday afternoon a hurricane force low
will lift along the Aleutian Storm track weakening to storm force
as it enters the Gulf of Alaska. While the highest storm force
winds remain well in the offshore zone, we are likely to see
southeasterly gales, to strong-gales, along our coast (near 40
knots) by early Monday morning, with fresh seas building to 15 ft.
On the backside of this low extensive southwest flow will drive
stout waves into our coast Monday afternoon/evening, bringing with
it 20-27 ft southwest swell along most of our coast, highest
significant wave heights aimed at Prince of Wales Coast/Dixon
Entrance. Another gale force low is anticipated Wednesday into
Thursday.


Inside (Inner Channels):
As of Saturday morning, near 1130, winds are currently reaching
their peaks as a front moves across the region. Overnight the
parent storm will track to the southeast, driving continued
northerly flow, with winds decreasing. By-and-large most of the
inner channels will remain below 20 knots; highest wind speeds of
fresh breezes are likely in Clarence Strait Sunday morning. By the
afternoon the supporting pressure gradient slackens as another
strong low lifts into the gulf, bringing elevated southeasterly
winds to most of the inner channels. At this time our current
forecast reflects strong breezes to near-gale force conditions for
most of the inner channels by Monday morning, potentially gale
force for Clarence Strait.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale Warning for PKZ663.
Small Craft Advisory for PKZ022-053-641>644-651-652-661-662-664-
671-672.

&&

$$

SHORT TERM...AP
LONG TERM...EAB/AP
AVIATION...EAB
MARINE...AP

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