Graphical Hydro Meteorological Discussion

400
FXAK68 PAFC 290010
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
410 PM AKDT Mon Sep 28 2026

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

This afternoon has been mostly quiet across Southcentral Alaska
with mostly to partly sunny skies and seasonable temperatures.
This will be short lived, however, as a shortwave trough is
progged to dig southeastward from the Interior tonight and into
Tuesday morning. Increased cloud cover ahead of this feature will
only allow temperatures to slowly cool tonight and most valley and
lower elevation areas outside of the Copper River Basin are on
track to see low temperatures 2 to 4 degrees F warmer than what
was observed this morning. Along with precipitation chances
increasing from Anchorage to the Susitna Valley, cold air
advection working in aloft with this wave will lower snow levels
to as low as 1800 to 2000 feet for the higher terrain of the
Matanuska and Susitna Valleys, which will support a quick round of
lower elevation rain showers and higher elevation snow before the
wave lifts over the Copper River Basin. Gap winds up to small
craft continue to gust around Kodiak Island as the remnants of
Dujuan move east through the Gulf. Winds slowly diminish through
mid-week as these final remnants dissipate.

For Wednesday, a longwave trough will move over the area with a
quasi-stationary surface low developing south of Seward. Weak lift
and weak winds aloft should help to bring steady precipitation to
the Sound and the population centers from the southern Matanuska
and Susitna Valleys and southward down into the Kenai Peninsula.
Even colder air will wrap in around the low bringing 850 mb
temperatures down to a range of -2 to -5 C depending on the
model. This would yield steady snow for areas like Thompson Pass
and even South Fork Eagle River and portions of the upper
Hillside. The NAM is a significant cold outlier and drops snow as
low as 800 ft, but we will continue to watch the progression of
temperatures aloft as we get closer in time. Overall confidence is
moderate (40-60%) that some of the upper elevations of Anchorage
and Eagle River will see some snow on Wednesday. Though winds
will remain sub-small craft, they will be elevated over gap
regions around Kodiak Island as this trough passes through.

-AM/JAR

&&


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

Key Messages:

* Colder temperatures move into Southwest Alaska throughout the
week.

* A front brings rain and small-force winds in the western
Aleutians starting Tuesday afternoon, spreading eastward on
Wednesday.

Discussion:

An active pattern continues across the Bering Sea and Southwest
Alaska as a series of upper-level lows and shortwaves move across
the region. A vertically stacked low is currently positioned over
the western Gulf. Cyclonic flow associated with this feature has
maintained showers across the Alaska Peninsula (AKPen), with much
of Southwest having cleared out. Some showers may linger in the
Kilbuck Mountains through this evening. Breezy northwest winds
continue in the eastern Bering and AKPen, especially through
favorable gaps. The vertically stacked low continues to move east
in the Gulf. With less support from cyclonic flow, any lingering
showers in the AKPen should taper off by tomorrow morning.

While the low in the Gulf continues to move away, another trough
digs southward across western Alaska and the Bering Sea on Tuesday.
This will allow a colder air mass to spread into Southwest
Alaska, with temperatures trending noticeable cooler compared with
recent days. Daytime temperatures will struggle to warm past the
low 40s for Southwest and the mid 40s for the AKPen, while
overnight temperatures become increasingly chilly throughout the
week, especially across the interior portions of Southwest
Alaska. Widespread low temperatures in the low 30s are expected
for Southwest tonight, dropping to the upper 20s by tomorrow
night. A weak surface low develops in the northern Bering tonight
and moves through the eastern Bering Tuesday. This looks to bring
some scattered showers across the Bering to the Pribilofs. Some
isolated showers may reach the Southwest Coast, otherwise Tuesday
looks to be dry for Southwest. This weak low moves towards the
AKPen and eastern Aleutians Tuesday evening. Chances for light
rain increase for places south of King Salmon. This system weakens
as it moves into the AKPen on Wednesday. Chances of precipitation
decrease throughout the day as showers become more isolated. The
trough with this system will allow the cooler pattern to persist
over western Alaska and the Bering, especially as more cold air is
pulled southward. Overnight lows Wednesday night look to be
cooler than earlier in the week, with high chances many locations
across Southwest drop to the upper 20s, with inland locations down
to the mid 20s. For the AKPen, cloud cover from the next Bering
system should help temperatures stay above freezing.

Farther west, the Aleutians currently sit underneath a weak ridge
which has resulted in relatively quiet conditions. A front from a
Kamchatka low moves into the western Aleutians Tuesday afternoon
and pushes this ridge east. This front looks to stall Wednesday
morning, though there is medium confidence on exact positioning
between the western Aleutian Chain and the Southwest Bering.
Nonetheless, showers and southeasterly to easterly small-craft
force winds are expected to accompany the front, especially in the
western Aleutians. The low eventually becomes elongated and
catches up to the front Wednesday night. Higher chances for
precipitation spread to the eastern Aleutians and eventually to
the Southern AKPen on Thursday as the low continues east. The area
of small- craft force winds also increases across the Aleutians
and Bering Wednesday- Thursday.

- PA

&&

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

An active weather pattern will continue as we make our way into
October. A cold upper level trough over the Interior on Friday
will begin to move out of the region for the weekend. The
departure of this low will bring a slight warming trend through
the weekend.

There are signs of slight ridging over Southcentral for Friday,
which will be the best chance to see some sun. This will be short
lived since a Gulf low is expected to bring rain and wind for the
weekend. Looking at integrated vapor transport from the GFS, the
values are low, so the low is not expected to generate a notable
amount of precipitation. Using the GEFS member spread, the pressure
gradient is nothing note worthy. No significant winds are expected
at this time Friday through Monday.

Another low from Kamchatka comes into the Bering Sea, then tracks
over the Aleutian Chain through the weekend. There is growing
model agreement of the low reaching peak intensity before going
through the Bering Sea. There is low confidence of where the
system goes after the weekend. Half of the members from the GEFS
have the centers of the low track into the Gulf, crossing over the
Alaska Peninsula. Other members have centers scattered around the
Bering.

&&

.AVIATION...

PANC...VFR conditions and light winds will persist for most of the
TAF period. There will be a potential for rain showers and lower
ceilings (possibly as low as MVFR) to return to the terminal late
Tuesday morning.

&&


$$

943
FXAK69 PAFG 282116
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
116 PM AKDT Mon Sep 28 2026

.KEY MESSAGES...
Central and Eastern Interior...
- Scattered rain showers in the valleys with snow showers
generally above 1000-2000ft through Wed AM. A flurry possible
in Fairbanks Tues night/Wed. Snow amounts 1 to 3 inches above
1000ft with a coating in Fairbanks.

- Snow likely in Isabel Pass tonight through Wed AM. 3 to 6
inches expected with another round of snow Wed eve into Thurs
with an additional 3 to 6 inches.

- More widespread light snow in the Interior Wed night into
Thurs with accumulating snow possible in Fairbanks.

- Temperatures drop significantly this week with highs for many
in the 30s by Tues/Wed and lows in the teens/20s.

West Coast and Western Interior...
- Remaining breezy for much of the Coast with max gusts up to 45
mph in the Bering Strait Region, weaker to the east. Winds
remain gusty this week, up to 30 mph Tues-Thurs.

- Light snow showers in the Bering Strait Region through Thurs,
totaling less than 2 inches, mainly near Shishmaref. Rain/snow
showers in the Interior with little to no accumulation.

- Temperatures continue to drop with highs mainly in the 30s
this week, lows in the teens and 20s, coldest in the Interior.

North Slope and Brooks Range...
- The main storyline for the next week will be chilly, cloudy
and periods of snow.

- Snow accumulations will range from 1 to 3 inches for most
spots through Thurs, heavier west of Anaktuvuk Pass with up to
6 inches. 1 inch or less near Wiseman.

- Temperatures cool into the mid/upper 20s for high in most
spots on Tues. Teens and 20s in the Brooks Range with a 1F to
3F temperature drop each day through Thurs. Warmest spots will
be from Kivalina to Point Hope, highs in the low/mid 30s.

&&

.SYNOPSIS...
A bit of active weather across the area as valley rain and
elevation snow showers persist through Wednesday in the
Interior. Another round of snow is likely Wednesday night and
Thursday with the first accumulating snow possible for many in
the Interior. Isabel Pass likely receives light to moderate snow
Monday night through Wednesday AM, with another round Wednesday
night into Thursday. Periods of light snow persist on the North
Slope through much of the week. The West Coast sees breezy
conditions through much of the week, strongest today while the
Interior has a few rain/snow showers. Otherwise, temperatures
will drop across Northern Alaska through the end of the week.

&&

.SHORT TERM /THROUGH THURSDAY/...
It`s a very messy pattern at 500mb with a weak upper low in the
Gulf, an open wave trough over the Interior and a closed trough
digging southeast from the Chukchi Sea. Starting in the
Interior, numerous lobes of vorticity will be meandering around
from northwest to southeast bringing valley rain showers and
elevation snow showers through Wednesday. For the most part,
snow showers across the Interior will be above 2000ft on Monday,
1000ft on Tuesday with a chance even in the valleys on
Wednesday as snow levels drop. Isabel Pass likely sees periods
of light snow this evening through Wednesday morning as well.
Snow accumulations remain light, around 1 to 3 inches in the
Interior terrain above 1000ft with 3 to 6 inches in Isabel Pass
during this time. Wednesday night and Thursday, a piece of
energy rounding the base of the trough will move northward from
the Gulf, towards the AK Range and Interior bringing another
round of snow. This will be running into a much colder airmass,
so snow is the most likely precipitation type across the
Interior. Additional snow accumulations will be 3 to 6 inches in
Isabel Pass with another 1 to 3 inches possible in the terrain
of the Interior and Fairbanks potentially getting its first
measurable snowfall this year. As you would infer, temperatures
are dropping this week. Monday will be the warmest day as
temperatures remain in the upper 40s to near 50 in the valleys,
but they will be dropping quickly in the low 40s tomorrow and
widespread low to mid 30s by midweek. This is driven by 850mb
temperatures plummeting from near 2C to -8C by the middle of the
week.

Elsewhere, Western Alaska is relatively quiet but we continue to
see gusty winds along the coast through much of the week. The
strongest winds come today, gusting 35 to 45 mph but these do
come down, with gusts of 20 to 30 mph through the rest of the
week. The gusty wind is mainly due to a surface high over
Russia running into a surface low in the Interior, allowing for
a semi-strong pressure gradient over the West Coast. There will
be a fairly weak Arctic trough dropping southeast as well, this
will provide enough support for snow showers from the Bering
Strait northward with light snow accumulations less than 2
inches in the Northern Seward Peninsula this week. Otherwise,
temperatures will be dropping through the week, with highs in
the mid/upper 30s for most spots by Tuesday, low/mid 30s on
Wednesday and continuous dropping by 1F to 3F each day
thereafter. Low temperatures likely drop into the teens and 20s,
especially away from the coast by Wednesday morning.

The North Slope remains active as periods of snow persist
through the end of the week. None of the snow looks particularly
heavy with accumulations around 1 to 3 inches through Thursday
across most of the Brooks Range, but there may be up to 6 inches
west of Anaktuvuk Pass. Winds will be gusty in the Brooks Range
through Tuesday afternoon, meaning there is a chance for some
blowing snow, mainly on top of Atigun Pass. Temperatures remain
chilly and do cool down this week widespread highs in the 20s by
Wednesday and even some teens on Thursday, especially in the
Brooks Range. Kivalina to Point Hope remains a bit warmer with
highs remaining in the low to mid 30s for most of the week.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Thursday through Saturday, a slow-moving arctic trough will
keep Northern Alaska locked into a pattern of below average
temperatures with periods of snow. The trough has several
smaller shortwave features embedded within it which make it
difficult to pin down the exact timing and amount of snow
expected. However, snow amounts through the entire 72-hour
period are expected to be less than inch across Central and
Eastern Interior Valleys, with 3 to 6 inches possible in higher
terrain. One caveat to this is the Eastern Alaska Range and in
particular Isabel Pass. This area will receive a greater amount
of moisture as the bottom of the trough passes over the Gulf of
Alaska and directs flow back north. As a result, Isabel Pass may
see between 6 and 10 inches of snow from Thursday until Sunday
morning, with the heaviest snow expected on Thursday. Areas
north of the Brooks Range will experience intermittent light
snow through the end of the week as well, which should shift
east through the period. The Western Interior and West Coast
should get hardly any snow as they remain under the influence of
drier northerly flow. Temperatures in the Interior should
bottom out between 20 and 30F with daily highs around 35 to 40F.
The coldest time for much of the Interior looks to be Friday or
Saturday morning, where locations with clear skies will likely
drop into the teens. Temperatures north of the Brooks Range will
remain below freezing, and may get as low as the single digits
along the Arctic Plains.

Attention turns to a low coming in from the Pacific as it
enters the Bering Sea on Saturday and approaches the southwest
Coast on Sunday. Ensemble low locations are mostly staying south
of St Lawrence Island, reducing potential coastal impact
concerns for areas north of Hooper Bay. There are still moderate
rain amounts and winds expected with this system, but impacts
appear minimal at this time. We will keep a close eye on it and
keep you up to date as the system approaches.

&&

Coastal Hazard Potential...
No great concern for coastal hazards over the next several days.

&&

.FIRE WEATHER...
Temperatures will be dropping with min RHs rising this week.
Expect highs in the upper 40s today, dropping to near 40 on
Tuesday with low 30s by the middle of the week. Min RHs will
largely be above 50% but may drop near 40% to 50% on Friday.
Winds will be a tad breezy beginning on Tuesday. Expect
northwest winds around 5 to 10 mph with an occasional gust to 20
mph. This continues into Wednesday, though shifting southeast
with a shift back to northwest on Thursday. A few gusts may be
up to 25 mph Thursday afternoon and evening. Some light snow is
also possible Wednesday night into Thursday, though
accumulations remain light and most likely less than 1 inch.

&&

.HYDROLOGY...
Interior rivers continue to drop to near normal values.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...None.
MARINE...Small Craft Advisory until 7 PM AKDT this evening for PKZ801-
805-810.
Small Craft Advisory until 4 PM AKDT this afternoon for PKZ802-
850.
Small Craft Advisory until 4 AM AKDT Tuesday for PKZ806-807.
Small Craft Advisory until 1 AM AKDT Tuesday for PKZ808-854.
Small Craft Advisory until 7 PM AKDT this evening for PKZ809.
Small Craft Advisory from 7 PM this evening to 4 AM AKDT
Tuesday for PKZ814.
Brisk Wind Advisory from 1 AM to 4 PM AKDT Tuesday for PKZ815.
Small Craft Advisory from 1 AM to 1 PM AKDT Tuesday for PKZ815.
Small Craft Advisory until 10 PM AKDT this evening for PKZ853-
855-856.
&&

$$

KEY MESSAGES...BIANCO
SYNOPSIS.......BIANCO
SHORT TERM.....BIANCO
LONG TERM......TROYKE
COASTAL........BIANCO
FIRE WEATHER...BIANCO
HYDROLOGY......BIANCO

372
FXAK67 PAJK 290607
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
1007 PM AKDT Mon Sep 28 2026

.UPDATE...Update after 06z TAF package and the Long term gridded
package done.

&&

.PREV DISCUSSION......ISSUED AT 343 pm Mon Sep 28 ...

SYNOPSIS...

Key Messages:

- Rain showers likely Monday night and through the day Tuesday.
Drying possible at times along the northern gulf coast on
Tuesday.

- Winds likely to remain gusty at times through early in the week.

- Temperatures mainly seasonable with highs averaging in the 50s.

SHORT TERM...A large upper level circulation over the gulf
continues to bring onshore flow Monday with showers scattered
across the entirety of the panhandle. A weak surface circulation
is expected to move into the northern gulf overnight into Tuesday
before gradually weakening and pushing inland in the vicinity of
Glacier Bay. This will lead to a weakening of the gradient over
the northern gulf and a brief transition to weak offshore flow
over the northeastern gulf coast. As this circulation progresses
into the northeast gulf on Tuesday, onshore flow and instability
aloft will become more conducive for thunderstorm potential to
shift to the southeastern gulf, to the coastal waters from Dixon
Entrance to southern Baranof Island. The primary impacts from
these would be erratic gusts and localized heavy rain quickly
reducing visibility.

Overall the pattern in the gulf remains unsettled through midweek,
as the low deteriorates and lifts inland, before another forms
near Cook Inlet and brings a fresh batch of moisture towards the
northern half of the panhandle. Temperatures will remain
relatively unchanged through the early week, though any areas that
see more clearing could see more overnight cooling, particularly
along the northeastern coast Tuesday night. With continued
saturation in the lower levels and persistent onshore flow, patchy
fog development is not out of the question tonight, though there
is higher forecast confidence for the northeast coast Tuesday
night.

LONG TERM.../Thursday through Sunday/...A series of small
disturbances and onshore flow will bring steady rain to the region
through the end of the week. A weak surface high building over
the southeastern Gulf will reinforce onshore flow and could
potentially tighten pressure gradients across the panhandle as the
next system approaches. A low pressure system originating near
Russia will move east, tracking south of the Aleutian Islands and
into the Gulf of Alaska by early weekend. There is a growing
likelihood of tropical moisture entraining into the system,
supported by an 850mb southerly jet, increased precipitable water,
and seasonably warmer temperatures aloft. Though this will likely
not affect the surface much due to consistent widespread cloud
cover and small diurnal trends.

Model spread is still significant, but guidance favors landfall
along the north-central coast late weekend. The system could bring
rounds of moderate to heavy rain across most of the panhandle, with
the highest totals currently expected along the northeast Gulf
coast, though this is dependent on the system`s exact track and
strength. There is also increasing potential for stronger winds and
building seas along the outer coast and northern inner channels
ahead of this low. While some guidance suggests a more aggressive
evolution, the system generally lacks upper level support beyond
a weak, negatively tilted trough and jet setup. We will continue
to monitor developments through the week.

AVIATION...After 06z TAF issuance.

Shower mode across nearly all of the panhandle area with areas of
the Southeast portion of the panhandle having the fewest showers,
and highest and strongest showers moving into Baranof and
Chichagof Islands and to the NE Gulf Southeast of Yakutat. A low
over the northern central gulf is drifting east slowly and but is
supporting a large area of enhanced looking showers from satellite
imagery.

Overall most of the panhandle is classified VFR but may drop to
the MVFR in the showers as the move into the area. A potential
concern near the showers may be gusty outflow winds, which could
have random directional shifts and speed shifts resulting in
potential wind shear at times.

MARINE...
Outside (Gulf and Coastal Waters): A 992mb low in the northern
Gulf of Alaska will shift eastward through Monday night, bringing
a swath of westerly fresh to strong breezes (17 to 27 kts) to the
southern gulf and easterly fresh to strong breezes (17 to 27 kts)
through the coastal waters of the northern gulf. Onshore flow will
continue to push developing showers into the northern panhandle,
spreading southward to envelop the rest of the panhandle by
tonight. A slight chance for thunderstorm development remains
today for the northeastern gulf coast, shifting southeastward
along the coast Tuesday to follow the showers.

The low center will continue to shift eastward through Tuesday
before falling apart as it makes landfall along the northeastern
Gulf Coast Wednesday. Winds in the northern gulf will become
relatively light and variable Tuesday before starting to increase
again from the southeast Wednesday. Winds in the southern gulf
will shift southwesterly and decrease to moderate to fresh breezes
(11 to 21 kts) through Wednesday. The gulf is currently
experiencing 8 to 10 ft wave heights with a 5 to 6 ft WSW swell at
a period of 10 to 12 seconds, which will decrease to around 5 to
6 ft with a 2 to 3 ft WSW swell at a period of 6 to 8 seconds
through Wednesday following the winds.

Inside (Inner Channels): Onshore flow from a system in the
northern gulf is bringing southerly moderate to fresh breezes (11
to 21 kts) through the inner channels and widespread shower
potential through Tuesday. Currently the strongest winds are being
observed through the northern and parts of the central inner
channels, but this swath will shift southeastward into the
southern panhandle as the system tracks eastward over the next 24
hours. Northern Lynn Canal is expected to continue blowing up to
20 kts through the rest of Monday before becoming light Tuesday
morning. Overnight, the central panhandle will feel the brunt of
the winds, with 15 to 20 kt southeasterly winds increasing through
Stephens Passage, Frederick Sound, and Southern Chatham Strait.
Through Tuesday morning, the strongest winds will be increasing
through Sumner and Clarence Straits. Winds will relatively
decrease Tuesday night before another system approaches from the
northern gulf, increasing winds back to fresh breezes (17 to 21
kts) through the N/S oriented inner channels up to 20 kts in
Northern Lynn Canal Wednesday. Wave heights of 3 to 4 ft are
expected in the areas of stronger winds through Tuesday,
decreasing to a widespread 1 to 2 ft overnight before increasing
to 2 to 3 ft again in windy areas Wednesday.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ641>644-651-652-661>664-671-672.

&&

$$

SHORT TERM...STJ
LONG TERM...BAS
AVIATION...Bezenek
MARINE...ZTK

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