Graphical Hydro Meteorological Discussion

586
FXAK68 PAFC 311323
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
523 AM AKDT Sun Aug 31 2025

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

Key Messages:

- Flood Warnings and Advisories remain in effect across Susitna
Valley. Most rivers have, or are currently cresting, and are
expected to fall over the next several days.

- Labor Day Weekend: Mild with a chance of light rain Sunday and
Monday afternoons for western portions of Southcentral. Localized
breezy areas in the afternoon and evening.

Discussion:

This mornings water vapor imagery shows a broad ridge stationed over
the Gulf with a shortwave trough moving through interior Alaska and
another shortwave lifting towards Nunivak Island and the Southwest
coast. Several more shortwaves can be picked out rotating around the
large low spinning over the Bering Sea. A nice fetch of tropical
moisture is being drawn up between the Gulf ridge and the Bering
low...funneling towards the eastern Aleutians, AKPen, and Bristol
Bay. A shortwave trough is starting to organize near Unalaska and
will be the next system to lift north towards Nunivak Island through
early afternoon. Widespread rain will move into Bristol Bay then
along the southern Alaska Range, spilling over into the Susitna
Valley by this evening. Models still have some disagreement with the
exact position of the rain axis. The NAM moves the rain in slightly
faster with rain moves in further east. The GFS is a bit slower and
keeps the main precip axis along and just west of the Alaska Range
due to having the trough digging deeper over the AKPen on Monday.
Light rain will spread into the Susitna Valley Monday night into
Tuesday as this next trough lifts north. Most of the rivers have
crested as of this morning, but could tick back up with additional
rainfall.

In addition to the light rain, there will be some areas that will
experience breezy conditions as each of these shortwaves moves
through the region. While the Copper Basin should remain generally
dry the next few days, the northern part of the basin could see some
scattered light rain showers work in from the west tonight and again
Monday night. The southern half of the Basin should see some of the
cloud cover scour out today. Bufkit model soundings do indicate more
of a inverted-V sounding profile late this afternoon resulting in
dryer low levels and breezy south winds.

- PP

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA / BERING SEA / ALEUTIANS
(Sunday to Tuesday)...

The forecasted atmospheric river event is in progress across
Southwest Alaska this morning. The culprit, a south-to-north
oriented front draped over the Alaska Peninsula, sits nearly
stationary between a deep occluded low over the Bering and high
pressure situated over the Gulf of Alaska. Rainfall has been
steady from the Alaska Peninsula up into the Kuskokwim Delta and
Kuskokwim Valley, and this should persist into Monday.

Very little has changed with the overall forecast and a
hydrologic outlook for the region covers expected rainfall totals
well through Monday afternoon:

* Togiak/Twin Hills: 2.5 to 4.0 inches.

* Dillingham: 2.0 to 3.0 inches.

* Manokotak: 2.5 to 4.0 inches.

* Clarks Point: 2.0 to 3.0 inches.

The main concerns with expected rainfall will be for higher than
normal river and stream levels, as well as water inundation and
ponding of water for low-lying areas.

Otherwise, widespread small craft winds will persist across the
Bering on Sunday, eventually tapering off later this evening.
Gales have been noted through the bays and passes around Cold Bay
with gusts up to and over 50 knots possible. This should hold true
through noon today, with the stronger gusts also diminishing over
the latter half of the day today. Winds for Bristol Bay should
become offshore and gusty as the low approaches from the south,
with northerly gap winds increasing through the Alaska Peninsula.

Conditions take a temporary reprieve on Tuesday morning as the
Bering front finally pushes into interior Alaska and the deep low
over the Bering lifts into the Bering Strait as an open-wave
trough. This should allow for rain to come to a halt over
Southwest Alaska for much of the day on Tuesday. A new system,
however, is forecast to lift into the Aleutians and Alaska
Peninsula from the North Pacific midday Tuesday. This will see
rain chances quickly return to Southwest Alaska Tuesday night and
Wednesday. Additionally, gusty offshore winds are anticipated over
Bristol Bay with northerly gap flow developing through the Alaska
Peninsula as the low approaches from the south.

BL

&&

.LONG TERM FORECAST (Days 4 through 7 - Tuesday through
Saturday)...

The long term forecast is similar to before. A longwave trough
sets up over the Bering while a stout ridge extends from the Gulf
of Alaska through the Alcan Border. This pattern will linger
until next weekend, when the ridge flattens out and allows the
trough to progress eastward.

Tuesday has a front from a north Pacific low move up into the
Alaska Peninsula. This steers the moisture flow from an
atmospheric river directly into the Alaska Peninsula and results
in heavy rain for the region as well as gusty gap winds.
Settlements such as Cold Bay and False Pass could see multiple
inches of rain through Saturday as this area continues to receive
rainfall and gusty winds as multiple fronts and lows move in from
the west. There is some uncertainty with the exact orientation of
the atmospheric river, so drier or wetter scenarios are possible.
Meanwhile, inland areas of Southwest Alaska will initially be dry
before the moisture plume pushes inland on Wednesday. Just like
the Alaska Peninsula, multiple fronts will push inland, bringing
multiple rounds of rainfall all the way through Saturday.

Southcentral is a completely different story. Apart from a front
that may bring rainfall to Kodiak Island and the Alaska Range on
Tuesday, the ridge will be present over the Gulf of Alaska at the
start of the long term on Tuesday. This means that drier
conditions as well as calmer winds will be prevalent. This
pattern will continue through Thursday. Friday is where things get
uncertain. Some guidance has a low move up the Gulf, bringing
heavy rains along the Southcentral coast and Kodiak Island where
as others don`t have this happening. There is some more agreement
on Saturday when the ridge flattens out and the trough out west is
able to move eastward. Heavy rains and gusty winds will follow
with some uncertainty on their exact placement.

-JAR

&&

.AVIATION...

PANC...VFR conditions will persist through the TAF period with
high clouds preventing fog formation this morning. Winds will
remain light and variable, with a southerly component at times,
today and less then 10 kts. Winds turn southeasterly this evening
but remain at 10 kts or less. The best chance for a few southeast
gusts to work in over the terminal looks to be tonight into
Monday morning. The core of strongest southeast winds and gusts
will remain over Turnagain Arm.

&&


$$

384
FXAK69 PAFG 312019
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
1219 PM AKDT Sun Aug 31 2025

.SYNOPSIS...
Continued wet weather for much of Northern Alaska for the next
week as the pattern keeps giving us southwest to west flow and
rounds of rain. Rivers are still the main concern moving through
the week as the rain does not stop. Fortunately the rain won`t be
as heavy as it was last week, but we are not anticipating any
major improvements for at least the next week. Otherwise, no
significantly impactful weather is expected for Northern Alaska.

&&

.KEY WEATHER MESSAGES...
Central and Eastern Interior...
- A few showers Monday morning, Tuesday morning and Wednesday
morning, especially from the Middle Tanana Valley north, but
light accumulations around 0.25" or less.

- AK Range gap winds up to 50 mph tonight through Tuesday morning.

- Warm and dry in the Upper Tanana Valley and Fortymile Country
with highs in the upper 60s and low 70s and minimal rain.

- Temperatures in the low to mid 60s elsewhere.

West Coast and Western Interior...
- Some sun this afternoon in the northern Interior, otherwise,
rain to the south moves over the Interior through the day.
- Periods of rain continue through Tuesday.
- 0.50 to 1.00 inches of rain through Tuesday with up to 2 inches
in the southern Seward Peninsula and higher terrain.

- Another round of rain possible Wednesday into Thursday.

- Temperatures remain cooler than normal.

North Slope and Brooks Range..
- Heavy rain in the southern slopes of the Central and Western
Brooks Range with up to 2" of rain today through Tuesday.

- Snow possible on the north side of Atigun Pass and up to Toolik
Lake tonight into tomorrow morning before changing to rain. An
inch or less of accumulation possible.

- Persistent periods of rain and rain showers for most of the
Brooks Range and North Slope through mid week.

&&

.FORECAST ANALYSIS AND DISCUSSION...
The pattern remains the same with a 590 decameter high in the Gulf
of Alaska and a trough from the Arctic to the NPAC. South to
southwest is expected to continue for Northern Alaska through the
week with numerous shortwaves and lows expected to provide rain
to the West Coast, Western Interior, Brooks Range and North Slope.
Isolated to scattered rain showers for the Central Interior and
nearly nothing for the Eastern Interior. Southerly flow over the
AK Range will provide mostly dry, chinook flow for much of the
Central and Eastern Interior but there will be periods of weaker
chinook flow where rain is possible.

&&

.FIRE WEATHER...
The Upper Tanana Valley and Fortymile remains warm and dry this
week with highs into low 70s. Min RHs may be as low as the upper
20s this afternoon, then largely increase into the 30s and 40s as
the week progresses. Winds will be breezy through Isabel Pass and
Delta Junction tonight through Tuesday morning with gusts as high
as 50 mph. Other than a couple of light showers in the Fortymile
on Tuesday, no rain is expected until Thursday night at the
earliest.

&&

.HYDROLOGY...
A variety of flood products exist across the Interior and Brooks
Range. Additional rainfall is likely through Tuesday with up to 2
inches possible in the Brooks Range, and generally 0.50 to 1.50
inches across Western Alaska. There will be very slow improvement
to the current river statuses this week and we expect them to
remain high. Additional waves of rain look likely during the
middle and end of the week as there is no end in site. For the
most updated forecasts and warnings, visit:

weather.gov/afg and weather.gov/aprfc

&&

.EXTENDED FORECAST DAYS 4-7...
A low in the Bering Sea will provide more rain to Western Alaska
through the week, especially in the Western Interior. From Monday to
Friday, there will be an additional 0.50 to 1.50 inches of rain,
widespread across Western Alaska, with the greatest amount on the
Southern slopes of the Brooks Range. A low traveling North across
the Aleutian Islands will begin to impact the West Coast as early
as Wednesday morning. The Brooks Range keeps chances for rain
each day, especially on the southern slopes. Scattered rain
showers with some mixed snow possible all next week on the North
Slope. Another low will begin to approach the West Coast of Alaska
and the YK Delta will be the first to see rain as early as Friday
evening.

Coastal Hazard Potential Days 3 and 4...None

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Flood Watch for AKZ813-814-819-828-831.
PK...Small Craft Advisory for PKZ801-804-805-810-816-852.
Small Craft Advisory for PKZ802-807-809-817-853-856.
Small Craft Advisory for PKZ803-855.
Small Craft Advisory for PKZ806-811-850-851-854.
Small Craft Advisory for PKZ808.
Small Craft Advisory for PKZ857.
Small Craft Advisory for PKZ859.
Small Craft Advisory for PKZ860.
Small Craft Advisory for PKZ861.
&&

$$

Bianco
Lewis - Extended

958
FXAK67 PAJK 312303
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
303 PM AKDT Sun Aug 31 2025

.SHORT TERM...
The panhandle remains largely dry and warm through the holiday
weekend and will continue to do so to start the week thanks to
persistent high pressure over the gulf. The one exception to this
otherwise benign pattern is marine stratus that formed over far
southern Clarence Strait and into Hecate Strait. While increasing
northerly winds Sunday night should scour out a decent amount of
it along the main channel, an eddy is expected to form east of
Annette and Duke Island, allowing for this stratus to accumulate
and rebound northward once more into SE Clarence and up into Misty
Fjords. Some of this low stratus, potentially low enough to
impact surface visibilities reaching Ketchikan and Metlakatla,
cannot be ruled out for Monday morning. Some isolated fog forming
and filtering down from interior valleys is also likely, with
highest confidence for Klawock. Similar to Sunday morning, the fog
and marine layer should diminish quickly with daytime heating.

Primary message to start the week is warming temperatures Monday
and continuing into Tuesday with highs reaching the mid to upper
70s Monday and isolated inland areas potentially reaching up to
80. Sea breeze circulations will be the dominant driver of winds
in the inner channels through the afternoon and evening hours
Sunday and Monday, though Clarence Strait will see pressure driven
sustained northerly winds due to thermal troughing extending into
Hecate Strait. For more information on this warming trend and the
heat advisory that was issued for parts of the southern
panhandle, see the long range discussion below.

.LONG TERM.../Tuesday into the weekend/...

Key Messages:
- High pressure over the gulf continues the warm, dry weather.
- Temperatures will be above normal through most of the week.
- Low rain chances (20-40%) return late this week and last into the
weekend.

Details:

Little changes to the inherited forecast for the upcoming week. The
broad upper level ridge and resilient surface level high will keep
the panhandle dry and warm, prolonging the clear skies and above
normal temperatures.

Max temperatures in the panhandle are expected to reach well into
the 70s up to around 80 on Tuesday and potentially Wednesday. Inland
areas will be the warmest as they won`t be impacted by sea breezes.
Confidence is high for well above normal temps with forecasted 850
mb temperatures aloft around 16 to 20 degrees Celsius with the
southern panhandle at the higher end of that range. When 850mb temps
get that warm, temps in the 70s are likely.

The second half of the weekend looks like a potential pattern
change. The high pressure looks to break down as a low pressure
approaches. The will bring increasing clouds Thursday with low
chances (20 to 40%) for rain Thursday night for Yakutat. Friday,
these low chances for rain spread into the rest of the panhandle.
These low rain chances last into the weekend. When these rain
chances actually move in will be highly dependent on when the high
pressure breaks down. If the ridge looks like it will linger,
then these rain chances will be delayed. Stay tuned.

&&

.AVIATION...
Widespread VFR flight conditions prevail as marine layer
continues to dissipate with CIGs generally AOA 5000ft with
isolated spots around 3000ft. By Sunday night, expecting
redevelopment of MVFR marine layer CIGS with IFR to LIFR visbys in
patchy fog, particularly across S panhandle TAF sites which has
persistently fogged out under this pattern. Any fog and marine
layer development should be similar to previous days, dissipating
and elevating through early afternoon.

Strongest winds through the rest of the afternoon up to and
around 15kts and gusts up to possible 25kts under any sea breeze
interactions. Winds largely return near 5kts or less and variable
overnight into Monday. No LLWS concerns through the TAF period.

&&

.MARINE...

Inner Channels: Local wind patterns from valley drainage winds at
night and sea breezes in the afternoons and evenings are still
the main forecast drivers. Some sea breezes could reach up to 20
kt in Icy Strait, and near Skagway. Otherwise lighter winds and
seas of 3 ft or less are expected into early next week. An
exception to this is Clarence Strait where NW winds of 15 kt are
expected to continue blowing, and ocean entrances where any NW or
W exposures will allow stronger NW winds up to 20 kt from the near
coastal water of the gulf to invade.

Outside Waters: The area of high pressure in the central gulf
will be rather persistent and is expected to last into the coming
week. Increased NW winds in the near coastal waters of the eastern
gulf have been observed and are expected to continue as pressure
gradients strengthen between the gulf high and the thermal low in
British Columbia. Currently seeing winds up to 20 kt gusting to 25
kt from Cape Fairweather southeastward and seas of around 5 to 8
ft (with a 3 ft swell from the W at around 10 sec). Highest seas
will be west of Dixon Entrance and off of Haida Gwaii. Winds are
likely to increase through Sunday night from Cape Ommaney
southward as the gulf high strengthens and will persist into
Monday.

&&

.FIRE WEATHER...
High pressure will keep much of the panhandle dry through the
holiday weekend and through the middle of the upcoming week. Low
risk for fire weather concerns remain, but fine fuels are being
watched. Lowest inland relative humidity expected around 30 to 50%
each afternoon where skies are clear mainly for early next week.
Warm temperatures expected through mid next week but somewhat
cooler for this weekend compared to this past Thursday and Friday
(60s and low 70s for highs expected) before another warm period
expected (70s or higher for highs) for the first half of next
week. Winds remain low except for localized sea breezes up to 15
kt in the afternoons.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Heat Advisory from noon to 7 PM AKDT Tuesday for AKZ319-325-328-
330-332.
MARINE...Small Craft Advisory for PKZ641-642-644-661-662-664.

&&

$$

SHORT TERM...STJ
LONG TERM...GJS
AVIATION...NM
MARINE...STJ

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