Graphical Hydro Meteorological Discussion

951
FXAK68 PAFC 210055
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
455 PM AKDT Sat Sep 20 2025

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

Weak ridging building from Kodiak Island into Cook Inlet in the
wake of the low in the Gulf has allowed the cloud cover across
much of Southcentral to thin out this afternoon, with a few
locations enjoying periods of sunshine. Any remaining radar
returns lingering along the coast or in higher terrain has
diminished this afternoon, although more prominent cloud cover
continues to blanket coastal areas.

The partly sunny skies and dry weather will be short-lived as
conditions revert back to wet, cloudy, and cool as the next upper
level trough digs down through the AK Peninsula tonight. Cloud
cover will be quick to return this evening amid weak flow and a
surface trough in the northern Gulf beginning to develop
downstream of the upper level trough. Return flow on the north
side of this trough coincident with increasing divergence ahead of
the next shortwave will result in rain overspreading much of the
Gulf of Alaska coast to inland areas again tonight into and
through the day Sunday. Rain will generally continue through
Monday morning before becoming more scattered and diminishing
throughout Monday afternoon and evening. A trough dropping in from
the Arctic and Northern Bering will interact with the low in the
Gulf of Alaska and should continue to provide rain chances through
the early part of the week. Active weather looks to continue
through the middle of the week as moist, southwesterly flow
resumes ahead of a large low and frontal system in the Bering as
it approaches the Gulf.

&&

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

A shortwave trough currently passing over the Pribilofs will
continue south across the AKPen by Sunday morning. The strongest
winds will be focused where flow channels through gaps and passes
along and south of the AKPen, with False Pass and King Cove
likely to see gusts around 40 to 50 mph from Sunday morning
through Monday afternoon. In the wake of the trough passage, cold
air advection will bring overnight lows from the low 40s to low
30s as cool, dry air settles into place. This northerly flow
regime will also begin to advect cooler air south from the Arctic,
initiating a steady cooling trend across Southwest through early
next week.

Monday morning, weak ridging is expected to bring a brief period
of clearing skies across the eastern Bering and Southwest
mainland. Attention then shifts to a much more potent low
pressure system expected to bring both strong winds and moderate
rainfall to much of the Aleutian Chain and western Bering. Good
model consensus supports this system becoming a high-end gale
force low as it enters the western Bering Sea from the North
Pacific late Monday, with surface pressure likely to bottom out
in the 970s mb range by Monday night. Strong gale force
southeasterly winds and rain will initially progress northwest
along the low`s occluded front, shifting from the western
Aleutians Monday afternoon to the eastern Aleutians and Pribilofs
by early Tuesday.

Tuesday morning, gusty southeasterly winds will switch to
westerly behind the front. A corridor of intense gusty wind with
the highest gusts of 50 mph up to 60 mph expected to impact an
area including Shemya, Adak, and Atka through the day. Sustained
winds could reach Storm force across portions of the marine areas
surrounding western parts of the Chain, depending on the peak
strength of the low.

&&

.LONG TERM FORECAST (Days 4 through 7: Wednesday through
Saturday)...

Forecast models are in good agreement at the beginning of the
long term forecast period on Wednesday with a deep occluded low
over the Bering and its front sweeping through the Aleutians. A
shortwave trough moving along the front should help with the
development of a triple point low as the front tracks from the
Alaska Peninsula to over Kodiak Island. The pattern will favor a
threat of winds gusting up to 50 knots across the Aleutian Chain
late Tuesday into Wednesday. As the front makes its way into the
Gulf of Alaska, widespread showers are favored with onshore flow
into the Gulf Coast and Southwest Alaska from Wednesday through
Thursday.

Friday into Saturday forecast confidence decreases significantly.
Models want to bring an upper trough from Northeast Russia into
Alaska, though the track of the low differs significantly
depending on preferred forecast model. The GFS has a more vigorous
wave digging southward along the west coast while both the
Canadian and EC keep the trough on a west-to-east trajectory,
bypassing Southwest and Southcentral Alaska entirely. Regardless,
colder temperatures are likely to filter into Southwest Alaska
behind the trough with a return of northerly gap winds through the
Alaska Peninsula and Eastern Aleutians possible by Friday.

BL

&&

.AVIATION...

PANC...VFR conditions are expected this evening and through
tomorrow morning. Weak flow and precipitation will likely yield
IFR ceilings and vis tomorrow morning, continuing through at least
midday. Winds will generally be light through the period, with
up-inlet flow prevailing by this afternoon.

&&
$$

927
FXAK69 PAFG 202215
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
215 PM AKDT Sat Sep 20 2025

.SYNOPSIS...
A mostly quiet, fall like weather pattern will continue across
much of Northern Alaska this weekend as isolated to scattered
showers persist. Temperatures will see a gradual cooling trend
through the start of the work week as an upper level trough works
southeast from the Arctic. With a low situated in the Gulf of
Alaska, this series of systems will continue to bring rain and
snow showers chances to much of the area through early next week.
As an Arctic trough axis works east across the state Monday into
Tuesday, snow levels will drop and support chances for snow across
higher elevations of the Interior as snow showers continue across
the Alaska Range, Brooks Range, and North Slope. A more active
pattern may develop thereafter, with the potential for a more
organized system moving in later next week. More on that below.

&&

.KEY WEATHER MESSAGES...
Central and Eastern Interior...
- Isolated to scattered rain showers through the weekend across
the Interior as temperatures see a gradual cooling trend.

- Rain continues in the Alaska Range, with snow above 4000 feet.

- Arctic trough passage later in the day Monday into Tuesday
will support more robust precipitation chances as snow levels
drop to 1000 feet or less around and west of Fairbanks, and
1000-2500 feet from Fairbanks south and east.

- Light snow possible in the White Mountains and hills
around Fairbanks, more likely in the Alaska Range passes.

- Highs in the 40s/50s this weekend, dropping to the mid to upper
40s Monday and Tuesday. Widespread frost/freeze conditions more
likely starting Monday and Tuesday nights.

West Coast and Western Interior...
- Isolated showers across Western Alaska into early next week.

- Arctic trough arriving Monday will drop temperatures for much
of next week as precipitation chances continue.

- Highs will be warmest today in the 40s/50s, dropping to the low
to mid 40s for Monday and Tuesday.

North Slope and Brooks Range...
- Onshore flow keeps stratus and areas of fog across the North
Slope and Brooks Range.

- Arctic trough arriving Monday will bring light snow to the
Western Arctic Coast, with snowfall amounts around a T-2".

- Light snow will continue its progression east Monday through
the Brooks Range, shifting east Tuesday, with amounts around
1-3".

- Snow showers persist across the North Slope and Brooks Range
for Tuesday.

- Highs in the mid to upper 30s along the Arctic Coast, 20s to low
30s in the Brooks Range.

&&

.FORECAST ANALYSIS AND DISCUSSION...Today through Tuesday.
Early afternoon satellite imagery over Northern Alaska shows a
mix of sun and clouds as a broad upper level troughing pattern
continues across the state this weekend. In this regime, we are
tracking three lows: one in the Gulf of Alaska, another further
north over the Beaufort Sea, and a third in the Bering Sea.
Moisture transport into the Interior from that Bering Sea low will
keep isolated showers going through the weekend with more
organized precipitation chances expected in the Alaska Range, as
snow generally stays above 4000 feet. Early next week, the Arctic
low further north will strengthen and send an arctic trough
southward across the North Slope and West Coast, leading to
noticeably cooler temperatures as colder air continues to build
into the Interior throughout the day Monday. This trough passage
Monday into Tuesday will support higher rain chances across much
of the Interior, with higher elevations seeing snowfall. Snow
levels will drop to 1000 feet or less around and west of
Fairbanks, 1000-2500 feet from Fairbanks south and east. Best
chances for accumulating snowfall will remain confined to the
White Mountains and potentially the hills around Fairbanks, with
any minor impacts likely centered around any light accumulation
along the Parks and Richardson Highways through the Alaska Range.

Heading into Tuesday, that arctic trough will continue its
progression east through the Eastern Interior, Brooks Range, and
Eastern Arctic Coast as isolated to scattered rain and high
elevation snow showers persist. Snow totals overall with this
system will continue to remain light overall, around a T-3" where
expected.

The most noticeable change with this arctic trough will be the
coldest temperatures across the Interior we have seen so far this
fall, with widespread frost/freeze conditions expected beginning
Monday and Tuesday nights. Fairbanks is currently in the running
for seeing a top 10 latest ever first freeze date, with records
dating back to 1905. Stay tuned next week to see which day it ends
up being.

&&

.HYDROLOGY...
No concerns at this time.

&&

.EXTENDED FORECAST DAYS 4-7...Wednesday through next Sunday.
Cooler and unsettled weather will continue through the extended
forecast, with a low working east through the Bering Sea into the
Gulf of Alaska for Wednesday into Thursday and Friday, supporting
isolated to scattered precipitation chances across Northern
Alaska. Persistent onshore flow across the North Slope should keep
snow showers going through the end of next week. On Friday,
models continue honing in on a strong low in Eastern Russia which
has the potential for a few different tracks as it works over into
Alaska. The ECMWF, GFS, and CMC ensemble members are all showing
the potential for an Interior Alaska track, which would
subsequently support widespread accumulating snowfall region wide.
The main caveat to this is the uncertainty in the strength and
position of this system, leading to low confidence this far out.
The latest operational runs of the ECMWF continue to favor that
track through the Interior, while the GFS in sharp contrast takes
the system southeast from Russia across Southwest Alaska, keeping
the bulk of rain and snow away from the Interior. The biggest
thing we will continue to watch for is how strong a ridge of high
pressure ends up being behind that low in the Gulf of Alaska late
next week, as that will be the main driving factor for where this
systems end up going. We will continue to monitor this evolving
pattern through the week as we track the latest.

Coastal Hazard Potential Days 3 and 4...None

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...None.
PK...Small Craft Advisory for PKZ801.
Small Craft Advisory for PKZ802.
Small Craft Advisory for PKZ805.
Small Craft Advisory for PKZ806.
Small Craft Advisory for PKZ807-856.
Small Craft Advisory for PKZ810.
Small Craft Advisory for PKZ811-857.
Small Craft Advisory for PKZ815-861.
Small Craft Advisory for PKZ816.
Small Craft Advisory for PKZ817.
Small Craft Advisory for PKZ850.
Small Craft Advisory for PKZ853.
Small Craft Advisory for PKZ854.
&&

$$

293
FXAK67 PAJK 210651
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
1051 PM AKDT Sat Sep 20 2025

.UPDATE...Area forecast discussion updated for 06z TAF issuance
and to reflect ongoing flooding in parts of the panhandle as well
as a High Wind Watch. Made changes to the marine section to
highlight the changes.

&&

.SHORT TERM.../ Through Sunday night / System has moved through and
region of showers and heavy showers area rotating into and
through the panhandle this evening and tonight. On Sunday another,
low moving northeast out of the north Pacific will bring a
980-ish mb low northward through the eastern gulf starting Sunday
afternoon/evening. This will bring a band of gale force, with
possibly storm gusts into the SE gulf Sunday night. Winds have
diminished and should be mainly less that 25 mph, but near some of
the stronger cells, gusts should be reaching 35 to near 40 mph.



.LONG TERM.../Monday through Thursday/...
Key Messages:
- Fast moving gale force system to move northward into the eastern
gulf Sunday night into Monday
- Heavy rain again for far southern panhandle
- Light to moderate showers continue across the panhandle through
midweek

An active fall pattern will continue early next week across
southeast AK as a strong gale force system moves up along the
outer coast through the day Monday. While another plume of
moisture will be aimed just south of the panhandle, this system
will tap into it and bring a burst of heavy rain to the far
southern panhandle late Sunday night into early Monday morning
before spreading moderate rain over a majority of the panhandle.
The primary impacts from this early week system however are
expected to be from strong winds due to the already saturated
ground across the area from rain experienced through the weekend.
Therefore

Ensemble guidance continues to give up to a 60% chance of upwards
of 3 inches in 24 hours for Metlakatla and Ketchikan for this
system. For the central outer coast including Sitka, guidance
gives a 60% chance of up to 2.5 inches over 24 hrs. These 24 hour
totals are for Sunday at 4pm through Monday at 4pm, with locally
higher amounts likely in steep terrain. Contingent upon the speed
and track of this feature, the timing of heaviest rainfall is
still expected early Monday morning as of this discussion.
Moderate rain, heavy at times, will then spread over the rest of
the panhandle from south to north as the low moves northward along
the outer coast.

While there is still some model discrepancy on the track of this
system, there has been a trend for it tracking further east over
the past few model cycles, giving increased confidence in the low
pushing inland somewhere along the northeast coast in the vicinity
of Cross Sound or further south along Baranof Island. Before the
primary track deviation point, there is model agreement on strong
gale force winds for the southeast gulf and Dixon Entrance area as
the low approaches, with gusts to 50 kt possible for far southern
Clarence Strait as well as southern Chatham Strait early Monday
morning and around the low center itself as it reaches peak
intensity Monday morning. Sustained winds up to around 25 kt with
frequent gusts to gale force are expected to spread northward
through the inner channels as the gradient tightens with the low
racing up along the outer coast. Seas in the southeast gulf will
also build to upwards of 18 ft with a southerly swell becoming
southwesterly on the backside as the system moves northward
through Monday afternoon.

Once the system moves inland, there will be persistent onshore
flow with light to moderate showers across the panhandle through
midweek. Late Tuesday and into Wednesday looks like the best
chance for increased breaks between showers, particularly for the
southern panhandle. Active pattern will continue however Thursday
as another low moves into the gulf bringing more enhanced rain to
the entirety of the panhandle. Throughout the forecast period,
maximum temperatures look to remain mild between the mid 50s in
the north ranging to around 60 in the southern panhandle as cloud
cover and rain showers reign supreme.

&&

.AVIATION...Lower CIGs and varying VIS prevail as showers pass
through the panhandle in the wake of an earlier frontal band. A
few fairly sheltered areas will see IFR CIGS through the overnight
hours. As these showers pass over, CIGs elsewhere will drop to
AoB 2000ft and winds will pick up. This will last until early
Sunday morning when a weaker frontal band reaches the panhandle
and drops CIGs and VIS with it. Greatest impacts for the southern
panhandle will be mid morning on Sunday, whereas the northern
panhandle may have a moment to break out before showers push north
later in the day. LLWS is still present at a majority of sites
through the overnight and early morning will be the most
impactful when showers pass through. Conditions will continue to
fluctuate through the period, often improving after showers pass
through and then dropping back down when more reach the panhandle.

It should be noted that beginning ~06z the 22nd a near storm
force low will advance from the south and bear down on the
panhandle. By ~06z, LLWS and strengthening wind speeds will
already be present in the far southern panhandle TAF sites. These
winds will race northward, and anticipate strong LLWS reaching at
least as far as the Icy Strait Corridor, with somewhat less
intense LLWS reaching into the northern panhandle. Further up, the
possibility of stronger turbulence will be present, especially for
areas south of Angoon (PAGN), for additional details, please refer
to the Alaska Aviation weather Unit.

&&

.MARINE...
Outside Waters: Post frontal winds primarily SW at 15 to 20 kt for
the outer waters and A Southwest swell headed to the panhandle
has Small craft seas of 8 or more feet, with a region of 13 to 16
ft seas headed towards the southern panhandle.

Inside Waters: Winds under 20 kt for inner channels tonight and into
Sunday. Localized gustiness near the showers as the move through
may abruptly shift wind directions and change speeds.

Update:

For Sunday night into Monday, a developing strong gale force low
will move up into the eastern gulf. An associated front will move
up Clarence Strait and into Sumner Strait early Monday morning.
With this front, strong gale force winds with storm force gusts
will push up over the marine areas. What is problematic with this
upcoming system is the string jet on the SE side of the low as it
moves closer to Baranof Island. While there are some questions,
with the current long term section still accurate for low
placement likelihoods, what is known is very strong gusts will be
associated with this low pressure. At this time, we are looking at
around a 50% chance for violent storm force gusts from the SW,
approximately 10 NM off the coast of Baranof Island.

&&

.HYDROLOGY...Moderate to heavy rains moved through the panhandle
on Saturday. An additional band of heavy rain will move through on
Sunday morning, followed by a more robust system Sunday night
through Monday Reports are the minor flooding is or will be
impacting Ward Creek Recreational area. Given reports of flooding
along Montana Creek impacting residents, an advisory has been
issued this afternoon. With the amount of rain incoming, a Watch
into early next week for the Juneau area has been issued.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...High Wind Watch from late Sunday night through Monday afternoon
for AKZ323-325-327-328-330-332.
Flood Watch through late Monday night for AKZ325.
MARINE...Small Craft Advisory for PKZ022-036-053-641>644-651-652-661>664-
671-672.

&&

$$

SHORT TERM...Bezenek
LONG TERM...STJ
AVIATION...GFS
MARINE...Bezenek
HYDROLOGY...Bezenek

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