Graphical Hydro Meteorological Discussion

424
FXAK68 PAFC 291401
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
601 AM AKDT Sat Aug 29 2026

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

Key Messages:

- Despite drier conditions today, rivers in Susitna Valley may
still be high this weekend as water level trends lag behind rainfall.

- This weekend`s gusty northerly to westerly offshore winds will
be strongest along the coast and in marine waters. Areas to watch
include Resurrection Bay, Prince William Sound (including Passage
Canal), Kachemak Bay, Kamishak Bay, and bays and passes along
Shelikof Strait.

- Colder conditions Saturday night through early next week,
including the potential for snow in mountain passes early Monday
morning and near freezing temperatures for lower valleys Tuesday
morning.


Discussion:

Last night`s system is quickly pushing east this morning with skies
trying to clear behind the trough as drier northwesterly flow takes
over. As the trough continues to move through the Copper Basin this
morning a compact surface low has developed near the Copper River
Delta with a moderate rain band wrapping around the low. The low is
currently moving inland and will weaken some as it moves into the
southeast corner of the Copper Basin and lower Copper River Valley.
While chances are low given lack of instability, there is still a
chance that this low is dynamic enough to squeeze out a lightning
strike of two as it moves inland. This system is moving out faster
than models are forecasting so have cut down on rain chances much
quicker today over the Copper Basin.

For the rest of Southcentral, today will some drier weather and
clearing skies as drier westerly to northwesterly flow takes hold
leading to gusty offshore winds, mostly along the coast and
extending into the Gulf. Inland areas will see light winds and with
minimal cloud cover later tonight, good radiational cooling will
allow temperatures to drop into the 40s for most inland locations
with the exception of the Copper River Valley where lows are
expected to drop into the 30s. Sunday will see another day starting
out dry but increasing cloud cover as the next system drops south
from the Seward Peninsula. This system will bring another round of
more widespread rainfall for Southcentral and a cooler airmass. This
will likely lead to higher elevation snow/termination dust, and
perhaps even snow at higher elevation mountain passes, like Broad,
Tahneta, and Thompson Passes. Whether the snow will stick will
depend on road surface temperatures - this early in the season,
probably not. For lower elevations, expect widespread rain and a
resurgence of gusty offshore winds. This system will move through
rather quickly and depending on how quickly we can clear out cloud
cover we could see temperatures drop into the 30s and frost
developing Tuesday morning for many lower elevations across
inland Southcentral.

- PP

&&


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

Weather across Southwest Alaska is less active as ridging builds
over the Bering. Mostly clear skies and cooler temperatures are
expected as northwesterly flow prevails. Low stratus and fog are
setting up over the coastal areas of Southwest Alaska. There are
also some areas of low stratus in the Bering. Due to this cold air
advection, elevated gap winds are expected in the Alaska
Peninsula today.

Shortwaves will ride over the strong ridge and will bring
rainfall and gusty winds to the Pribilof Islands by Sunday
morning. By early Sunday afternoon, the shortwave will move
inland, bringing widespread rain to the Southwest Mainland. For
the area under the ridge (from the Adak to Unalaska regions),
winds can still be gusty, but rain chances will be minimal. Gusty
winds will return to the Alaska Peninsula Sunday afternoon, but
winds will be more southwesterly, so gusty gap winds are less
likely. This pattern of shortwaves riding over the ridge will
continue through Monday and likely trough mid-week, leading to
repeated bursts of rain and gusty winds from the Adak and Atka
region, through the Pribilof Islands, and into the Alaska
Peninsula. Fog and low stratus will be possible over the area of
ridging and in-between shortwaves elsewhere. A strong upper low
will drop over the Southwest Mainland on Monday, drying things out
and potentially leading to low temperatures dropping into the 30s
for far inland areas due to cold air advection.

-JAR

&&


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

The overall upper-level pattern through Wednesday will be
dominated by a ridge of high pressure extending from the
North Pacific across the Aleutian Islands and southern Bering Sea
with a negatively tilted trough with axis extending from the
Chukchi Sea southeast to the eastern Gulf of Alaska.

Multiple shortwaves and vorticity maxima with move from northwest
Alaska into the Gulf, embedded in the northwesterly flow aloft.
For Tuesday, the first of these features will help maintain gusty
gap winds from Alaska Peninsula east across the immediate
Southcentral coast to Prince William Sound. A transient ridge in
the wake of this wave will provide some warm air advection,
allowing snow level to rise from an expected minimum around 3,000
ft on Monday. A second, weaker wave moves through on Wednesday,
allowing for a return of scattered showers across the Alaska Range
and the higher terrain surrounding the Copper River Basin.

By late Wednesday, the upper-level pattern looks to become more
amplified, with the North Pacific Ridge moving east and lifting
across the Southern Mainland Thursday morning. The eastward
progression of this ridge will allow a trough over the western
Bering to deepen, resulting in a stout southerly wind flow between
the two features. A strong shortwave will move north along a
stalled frontal boundary, leading to the development of a surface
low somewhere between the Pribilofs and Kuskokwim Delta coast.
This feature, along with its surface front, will drive into
Southwest Alaska with another round of heavy rain and gusty
southwesterly winds along the coast for Thursday.

By late Thursday, model agreement begins to break down more
significantly, particularly with regard to the eastward
progression of the upper-level ridge. The GFS and Canadian models
are favored for the long term forecast, both of which slide the
ridge axis over the Alaska Panhandle by Friday. The resultant flow
aloft becomes more southwesterly across the Alaska Peninsula and
Southern Mainland as the trough also slides east. Multiple
shortwave then looks to lift from the North Pacific to the Alaska
Peninsula by the end of the week, with more rain and gusty winds
for much of Southwest and western half of Southcentral Alaska as
yet another storm system drives north across western Alaska.

- TM

&&


.AVIATION...

PANC...VFR conditions and light winds anticipated through the
period.


&&


$$

954
FXAK69 PAFG 292318
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
318 PM AKDT Sat Aug 29 2026

.KEY MESSAGES...
Central and Eastern Interior...
- Drier conditions expected for the rest of Saturday as higher
pressure builds in from the southwest behind the rain.

- Breezy west/southwest winds are expected across much of the
Interior Saturday, with gusts peaking around 25-35 mph for
most locations.

- Another low moves southeast from the Chukchi Sea across the
Interior Sunday into Monday.

- Rainfall accumulations Sunday into Monday are expected to be
around 0.10-0.50", with higher amounts along the northern
Alaska Range around 0.50-1.00". Snow levels around 3-4,000
feet will support snow across higher elevations of the
Interior, with heaviest totals in the Alaska Range.

- Highs are expected to remain in the 40s and 50s through early
next week, with overnight lows in the 30s to low 40s. Clearing
skies Monday night may allow for some isolated valley
locations to reach near freezing early Tuesday morning.

West Coast and Western Interior...
- Another low approaches the West Coast from the Chukchi Sea
late Saturday into Sunday. This system will bring another
round of rain, high elevation snow, and breezy winds through
early Monday.

- Rainfall accumulations tonight through Monday are expected to
be around 0.10-0.50", with dry conditions favored out at St.
Lawrence Island. Snow levels around 1,000-2,000 feet will
support light snow across higher elevations of the Seward
Peninsula, Western Interior, and Brooks Range.

- Southwest winds gust around 20-30 mph across the West Coast
through Saturday. Winds will increase on Sunday, shifting to
the northwest with gusts up to around 25-45 mph.

- Highs in the 50s to low 60s Saturday, drop to the the 40s/50s
early next week, with overnight lows in the 30s and 40s.

North Slope and Brooks Range...
- Winds, rain, and snow from the previous low exit the region to
the east late Saturday.

- Another low moves through the Chukchi Sea Sunday. It spins up
a broader area of low pressure that will keep most of the
North Slope breezy and showery through much of the upcoming
week.

- Rainfall accumulations late Saturday through Monday are
expected to be around 0.10-0.50" (highest farther west), with
drier conditions expected around Deadhorse to Kaktovik with a
T-0.10". Snow levels around 1-2,000 feet will support light
snow across higher elevations of the Brooks Range, with around
a T-2" expected.

- An uptick in winds will accompany this system, with gusts
peaking around 15-30 mph, strongest across the Arctic Coast
and higher elevations of the Brooks Range.

- High temperatures today will be warmest farther west in the
50s to around 60, as locations farther east stay in the
30s/40s. That warmer airmass will shift east Sunday as highs
stabilize starting Monday in the 30s/40s. Overnight lows will
be in the 30s/40s, locally cooler in the Brooks Range in the
20s/30s.

&&

.SYNOPSIS...
The previous low departs the region to the east. The next system
move into the Chukchi Sea late Saturday and then shifts
southeast through Sunday and early Monday. It will bring cooler
temperatures, breezy winds, and widespread light to moderate
rainfall across most of Northern Alaska Sunday into early
Monday. A brief period of calmer weather follows Tuesday before
another strong low in the Western Bering extends a front to the
West Coast Wednesday and Thursday which brings more wind and
rain to the area.

&&

.SHORT TERM /THROUGH TUESDAY/...
At the start of the forecast period, Saturday, the last remnants
of the previous low pressure system exits the region to the
east. Higher pressure builds in from the southwest, sourced from
a large and strong high pressure over the North Pacific. Up
until now this high has been the main driver of our weather by
forcing low pressure systems in the Western Pacific into the
Bering Sea. Our next low pressure system is not coming from the
Bering Sea though. A strong upper level low moves east out of
Siberia Saturday morning into the Chukchi Sea. This upper level
low quickly spawns a surface low over the water that peaks in
strength around 995 millibars. The upper level feature moves
southeast across the Interior late Saturday through Sunday
reaching the Gulf of Alaska by Monday morning. The surface low
beneath it is pulled apart trying to chase it southeast and ends
up rapidly weakening. A weaker surface low does follow the upper
level low south east which helps to support another round of
rain that sweeps across the Interior. This low, being sourced
from the Arctic rather than the Pacific, is significantly less
wet than previous storms with rainfall totals in the 0.10 to
0.50 inch range. The exception will be the northern slopes of
the Alaska Range where upslope flow will significantly enhance
precipitation. Due to the unseasonably cold nature of the
supporting upper level low snow accumulations will be possible
at higher elevations across the Interior.

After this low moves through the region, troughing remains over
much of Northern Alaska. A surface low remained over the Arctic
Ocean north of the North Slope from what was sheared off of the
surface low from earlier. Another upper level low moves
south from near the North Pole towards this area and settles.
This reinforces the troughing over the northernmost portions of
the state and allows for smaller features like shortwaves to
move over the North Slope in waves through much of the upcoming
week. The high pressure over the North Pacific attempts to push
against this troughing pattern which allows for some higher
surface pressure to build into the Interior following the rain
early next week. This allows temperatures to recover and warm
Tuesday through much of next week.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
At the start of the extended forecast period, late Tuesday, low
pressure remains over the North Slope, but higher pressure
builds into the West Coast and Interior to moderate the cooler
and more showery conditions of the early week. The next system
of note moves into the Western Bering Sea late Tuesday into
early Wednesday. This low absorbs another low into it and
rapidly strengthens into the 970 millibar range Wednesday. A
front spins off of this low Wednesday and moves towards the West
Coast late Wednesday into Thursday. The low remains in the
Western Bering Sea which will keep the impacts lower, but the
front itself will bring another round of moderate to heavy
rainfall and gusty winds to the West Coast and Western Interior
Wednesday into Thursday. The low itself meanders about in the
Western Bering Sea through the end of the week, potentially
getting close enough to affect the West Coast again Friday into
Saturday, although it will likely have significantly weakened by
then.

Coastal Hazard Potential...
No major concerns. A low moving southeast from the Chukchi Sea
towards the Western Interior Sunday will cause winds to shift to
the west/northwest around 25 to 40 mph. These winds will
increase water levels by around 1 to 2 feet above the normal
high tide line along the Chukchi Sea and Norton Sound Coast. The
far eastern Norton Sound and the Kotzebue Sound will see the
higher end of this range with the high tides Sunday into Monday.
Late next week another large low pressure system in the Western
Bering Sea may start to push towards the West Coast which could
cause some coastal impacts, but there is too much uncertainty in
its track to determine the strength and location of any impacts.

&&

.FIRE WEATHER...
Fire weather concerns remain low through early next week as
conditions stay well outside of threshold values. Upper level
ridging shifts eastward into Canada Saturday night, with remaining
showers east of Fairbanks tapering off near the Alcan Border by
midnight. South to southwest winds with gusts of 25 to 35 mph will
diminish through the evening, allowing relative humidity values to
make an overnight recovery to above 80 percent. A 995 mb surface low
drops southeast out of the Chukchi Sea, triggering widespread
wetting rain across the Interior Sunday into Monday. General
rainfall totals of 0.10 to 0.50 inches are expected, with 0.50 to
1.00 inches favored along the northern slopes of the Alaska Range.
West to northwest winds will increase Sunday night into Monday, with
gusts peaking between 20 and 40 mph, strongest across higher
elevations and the Upper Tanana Valley. Minimum relative humidity
values drop back to 40 to 50 percent in the Eastern Interior Tuesday
and Wednesday.

&&

.HYDROLOGY...
Following several rounds of rain across the West Coast and the
Western and Central Interior, rivers and streams have risen
above normal. Another low is expected to move from the Chukchi
Sea southeast across the Interior Sunday into Monday which will
bring another 0.10 to 0.50 inches of rain to much of the
Interior. Higher amounts are possible along the northern slopes
of the Alaska Range. This will help keep water levels high, but
no flooding is currently expected.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...None.
MARINE...Small Craft Advisory from 10 PM this evening to 7 AM AKDT
Sunday for PKZ801.
Small Craft Advisory from 1 AM to 7 AM AKDT Sunday for PKZ802-
803.
Small Craft Advisory from 1 PM to 6 PM AKDT Sunday for
PKZ802>804.
Small Craft Advisory from 1 AM to 10 AM AKDT Sunday for PKZ804.
Small Craft Advisory from 10 PM this evening to 6 PM AKDT
Sunday for PKZ805-852.
Small Craft Advisory from 1 AM to 6 PM AKDT Sunday for PKZ806-
807-817-854.
Small Craft Advisory until 7 PM AKDT this evening for PKZ807-
811.
Small Craft Advisory from 7 AM to 10 AM AKDT Sunday for PKZ808.
Small Craft Advisory from 7 AM to 1 PM AKDT Sunday for PKZ809-
855.
Small Craft Advisory from 7 AM to 6 PM AKDT Sunday for PKZ816-
856.
Small Craft Advisory from 4 PM to 6 PM AKDT Sunday for PKZ850.
Small Craft Advisory until 4 PM AKDT this afternoon for PKZ851.
Small Craft Advisory from 10 AM to 6 PM AKDT Sunday for PKZ851-
853.
Small Craft Advisory from 7 PM to 10 PM AKDT this evening for
PKZ856.
&&

$$

KEY MESSAGES...Stokes
SYNOPSIS...Stokes
SHORT TERM...Stokes
LONG TERM...Stokes
COASTAL HAZARD POTENTIAL...Stokes
FIRE WEATHER...Satcher
HYDROLOGY...Stokes

123
FXAK67 PAJK 292259
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
259 PM AKDT Sat Aug 29 2026

.SYNOPSIS...

Key Messages:

- An active weather pattern will persist through the weekend as
several fronts move over the panhandle.

- A brief lull in heavier rain showers is expected Sunday before a
stronger low moves into the Gulf, bringing another round of
precipitation through Monday.

&&

.SHORT TERM.../through Monday/...Several upper level troughs
passing over the region are driving this active weekend pattern,
with a weaker digging trough currently moving precipitation
through tonight before a stronger low associated with an upper
level jet enhances the system on Monday and Tuesday. Organized
bands of precipitation should begin to clear out this evening with
mainly lighter spotty showers expected tomorrow with daily totals
around 0.1 to 0.6. Activity will pick back up overnight Sunday
initially near Yakutat, bringing heavier rain rates of 0.1 to
0.2 per hour by early Monday morning. As the front moves south on
Monday, expect lower totals for the southern regions,
specifically over Prince of Wales Island as most precipitation
will be enhanced by higher elevations. 24 hour accumulations from
Monday into Tuesday morning are expected around 1.5 to 2.5 over
the north and 0.75 to 1.25 over the south. Additionally, while
winds will diminish on Sunday, they will increase again Monday
morning in Lynn Canal and Stephens Passage, with higher gusts
possible over northern land zones.

Across the panhandle today, temperatures remain in the 50s to low
60s. Breaks in rain tomorrow could drive a slight warming trend
with highs reaching the upper 50s to mid 60s. The greatest chance
for clearing skies tomorrow will be in northern areas. As the next
system moves through on Monday, temperatures will cool back down,
with most locations remaining in the 50s.

.LONG TERM...

Largely uneventful long term in terms of impact, but several
interesting features and tidbits. The first being Tuesday morning,
as the stronger low moves down from the NE gulf coast towards
Dixon Entrance. Rather strong surge of cold air looks to be
associated with this low; and with some leeside troughing from
northwesterly winds, it could be as low as 990 mb near Yakutat
with 850 mb temperatures dropping below 0 C. As a result,
expecting lapse rates around the low center to be stronger. With
strong vorticity advection, expecting plenty of lift with the
possibility of thunderstorms in the outer coast. Most of the rain
accumulations look to be on the outer coast with persistent
onshore flow, but since this low looks relatively transient, not
expecting any one area to have extended periods of moderate to
possibly heavy rainfall.

As it moves towards the southern panhandle, another shortwave
trough looks to come across the gulf waters, merging with the
existing low near the panhandle, strengthening it again. There is
some uncertainty on exactly how this shortwave will merge with the
ongoing system, but definitely trending towards impacting the
Canadian areas.

Going into the mid to late week, high amplitude ridging returns
with northwesterly flow, drier conditions, and warmer
temperatures.

&&

.AVIATION...Difficult day for aviation concerns. Many areas of
the panhandle are observing vis around 3 to 5 miles and ceilings
down to 1500 ft or less. A few locations are even down to 1 mile
vis (Sitka and Yakutat) and a few hundred feet ceilings (also
Sitka and Yakutat). This is due to the second of two fronts that
are moving through the area today. This front moved onshore early
this afternoon and is just reinforcing the already low conditions
that many areas were seeing this morning mainly from Cape
Fairweather S and E. The low conditions and rain is expected to
last into the evening with rain gradually diminishing afterwards
with some improvement in vis. However, ceilings will likely stay
low for many areas through the night and will not see significant
improvement until Sunday morning and even then will likely stay
with MVFR conditions.

Surface winds have been somewhat gusty in some areas, but only
gusting to around 25 kt today. With the front moving through this
evening these winds will likely not diminish until late this
evening. Aloft, winds have not been much higher than what is seen
at the surface and pilot reports have only had some isolated
areas of light turbulence at low altitudes today (and little to no
low level wind shear reports). These wind conditions will likely
remain consistent through the evening and will likely improve
later tonight as the fronts move out of the area and winds
lighten.

&&

.MARINE...Inner Channels: Inner channel winds today have not been
that strong. Highest winds have been on the backside of Douglas
Island (E wind 25 kt most of the day), Northern Lynn, and Clarence
Strait (20 kt in both places at various points today) so far. At
least for this system, right now is about as high as inner
channels winds are going to get. The second front that is moving
through right now is not as strong as the first one last night was
and winds are expected to gradually diminish into Sunday.
Likewise seas are around 4 ft or so for most areas and will
gradually subside as the winds do. Of greater concern has been the
reductions in visibility due to rain and fog. Some areas have
been as low as 1 mile and more areas that low will likely be
encountered through the evening and overnight before improving
Sunday. There is another period of higher winds and seas expected
for Monday as a new front moves in at that time. Wide spread
southerly winds of 20 kt expected across the northern 2/3rd of the
inner channels starting late Sunday night and continuing through
Monday night before diminishing. Highest winds will be in Lynn
Canal where 30 kt winds could be observed Monday morning.

Gulf Waters: Somewhat active gulf of Alaska over the next few
days. At least two lows will be moving SE through the eastern gulf
from the Prince William Sound area. Overall the wind pattern over
the gulf favors W to NW winds over the offshore marine zones,
while the winds directions will be more variable near the coast
switching from S and SW ahead of each low, becoming more easterly
as the low passes, and finally becoming more N and NW in the wake
of the lows. Highest winds will be with the second low that will
be moving through Monday into Tuesday with near gale expected for
the central gulf waters. Near coastal waters will feature weaker
winds of around 20 kt or so even with the second stronger low.
Seas will be going up and down as well with up to 8 ft seas for
the current system and up to 13 ft seas out in the central gulf
for the second system. In between systems on Sunday, seas will be
as low as 6 ft. predominate swell will be around 3 to 5 ft out of
the W for most of the next few days.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ661>664-671-672.

&&

$$

SHORT TERM...BAS
LONG TERM...NC
AVIATION...EAL
MARINE...EAL

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