Graphical Hydro Meteorological Discussion

278
FXAK68 PAFC 101343
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
543 AM AKDT Sun Aug 10 2025

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

Discussion:

Early morning satellite imagery shows that the trough progged to
drop southwards across west-central AK is steadily moving inland.
Models are still in good agreement that it will track towards the
northern Susitna Valley by this evening before dropping towards
Prince William Sound and onwards towards the Panhandle. Scattered
showers have redeveloped this morning from the western Kenai
Peninsula north into the Mat-Su Valley as lift increases ahead of
the front that is just off to the west. Showers will be maximized
over the northern Susitna Valley and along the Alaska and Talkeetna
Mountains this morning as the front moves in. A secondary round of
more showery precipitation will accompany the upper low as it moves
through the Susitna Valley later this evening. While an isolated
thunderstorm can`t be completely ruled out, skinny CAPE profiles
in Bufkit suggest limited instability and it is doubtful that we
will see enough of a break in cloud cover this morning to bump up
instability. Elsewhere, intermittent, light showers will be
possible this morning and again this afternoon and evening.

Precipitation will push eastwards into the Copper River Basin by
Monday morning. While much of the basin will see scattered showers,
lightning chances look best over the northern half of the basin.
Precipitation will move out of the Basin by Monday evening with
shortwave ridging building in behind. This will allow for a rather
nice day for much of Southcentral on Tuesday and into Wednesday.

- PP

&&


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

A weak surface low with a strong upper-level component centered
along the west coast of Alaska continues to spread a cooler
airmass across Southwest Alaska, bringing low temperatures in the
mid to low 40s this morning. An embedded shortwave rotating around
the upper low is producing a band of light rain which is dipping
south into the Lower Kuskokwim Valley this morning. This band of
precipitation will sweep eastward and lift into the Upper
Kuskokwim Valley by midday, returning dry conditions with mostly
sunny skies to Southwest Alaska. Another cool day is forecast with
high temperatures in the mid 50s to low 60s, and clear skies
tonight will likely bring some locations down into the 30s.
Temperatures rebound somewhat as transient high pressure builds
into Southwest Alaska on Monday, keeping the dry regime in place.

High pressure in the eastern Bering Sea today promotes continued
stratus, though the colder air mass aloft has lifted ceilings
somewhat and alleviated the region from fog. Later today, much of
this stratus looks to mix out along the Alaska Peninsula and in
the eastern Aleutians, which should allow for a mostly sunny day.
Where the colder air aloft`s influence does not extend, along the
central Aleutians, areas of fog are present. However, a Kamchatka
low extending a front across the western Bering Sea and across the
western Aleutians tracks eastward today, pushing the front into
the central Aleutians, which will scour out the fog and replace it
with light to moderate rain, gusty southerly winds, and the
potential for an isolated thunderstorm. A corridor of gales
develops further north in the western Bering Sea, which shifts
into the north-central Bering tonight.

The Bering front progresses eastward across the Pribilof Islands
Monday morning and reaches the Kuskokwim Delta coast by Monday
afternoon. Roughly around the same time, it appears likely that a
North Pacific low tracks to near the central Aleutians and
reinvigorates the southern portion of the front. This has the
potential to extend gale force winds across the length of the
front from the central Aleutians, across the Pribilof Islands, to
the Kuskokwim Delta coast. However, the evolution of this low has
shifted to keep more of the energy focused further south, along
the Aleutians, which should prevent a prolonged push of gale
force winds onshore of the Kuskokwim Delta.

The coastal flooding concern remains low, but non-zero, for the
communities of Kipnuk and Kwigillingok. Water levels are not
likely to exceed 2 feet above the normal highest tide line during
the Monday or Tuesday afternoon high tides. However, the prolonged
southerly wind could lead to localized erosion due to rough seas
along the coast.

The front pushes inland over Southwest Alaska Tuesday night,
leading to fairly widespread rain showers. Meanwhile, gusty
westerly winds and relatively cooler air begin to overspread the
Bering Sea.

CQ/TM

&&


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

Upper- level troughing across the Bering Sea and western Alaska
stretches from the Arctic down to the Alaska Peninsula at the
start of the long term forecast period. The wave of moisture
moving across western Alaska will get pushed into Southcentral on
Wednesday as a triple point low forms south of the Kenai
Peninsula, bringing moderate precipitation to the southern half of
the state. Cool temperatures aloft could result in some of the
high peaks of the Talkeetna and Chugach mountains receiving their
first termination dust of the season. Model guidance deteriorates
greatly as this feature progresses into the eastern Gulf on
Friday, but a generally quieter weather pattern should settle in
across most of the state by the end of the week. Expect near
normal temperatures with highs forecast to be generally in the
60`s.


&&

.AVIATION...

PANC...VFR conditions expected to persist through the TAF period.
There is a chance for ceilings to dip into MVFR Sunday morning
with scattered showers. Up-inlet and Turnagain Arm wind will
increase through 00Z then subside. Peak gusts up to 27 knots
expected.


&&


$$

400
FXAK69 PAFG 092103
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
103 PM AKDT Sat Aug 9 2025

.SYNOPSIS...
Showery conditions move from the Western Coast east across the
state through Sunday. Pressure briefly builds behind the showers
from the west before another system reaches the West Coast Monday.
This next system will be stronger and wetter bringing strong
southerly winds, high surf, and heavy rain to large portions of
the West Coast and Western Interior through Wednesday.

&&

.KEY WEATHER MESSAGES...
Central and Eastern Interior...

- Moderate to heavy rain showers move east into the Central
Interior today and into the Eastern Interior Sunday.
-Rainfall Total estimates through Sunday
-Central Interior: 0.25 to 0.75 inches
-Western Alaska Range: 0.75 to 1.25 inches
-Eastern Interior above 1500 feet: 0.25 to 0.50 inches
-Eastern Interior below 1500 feet: 0.10 to 0.30 inches
-Upper Tanana Valley: Up to 0.10 inches.
-Due to showery nature of this rain some small areas could see
more or less than these amounts, but these are the most likely
amounts.

- Isolated thunderstorms possible across the Interior on Saturday
and along the AlCan on Sunday.

- Cool temperatures expected briefly behind this rain Sunday and
Monday with highs in the mid 50s to low 60s. Slight chance of
frost in cooler Interior Valleys Monday morning, but only in
areas where skies clear.

- Additional rainfall expected later this week most likely
Thursday and Friday.

West Coast and Western Interior...

- Widespread rain today, heavy at times. Strong north winds to 40
mph along the coast that diminish this evening through tonight.
-Saturday Rainfall Totals:
-Western Interior: 0.10 to 0.25 inches, increasing further east.
-Seward Peninsula: 0.10 to 0.25 increasing further west. Higher
amounts up to an inch possible along northwest facing slopes.

- Relatively dry Sunday with lighter scattered showers.

- Bering Sea storm Monday into Tuesday.
-IMPACTS: 2 to 4 feet water rises possible, highest in the Norton
Sound. Wave run up and minor beach erosion possible. Heavy rain
at times Monday through Wednesday with 1 to 2 inches expected
along the West Coast.
-TIMING: Highest water levels expected Monday afternoon through
Wednesday morning south of the Bering Strait.

North Slope and Brooks Range..

- Heavy rain in Western Brooks Range with lighter rain across the
Western North Slope and Arctic Coast today through Sunday.
-Estimated rainfall totals of 0.10 to 0.25 inches expected for
the North Slope with 0.25 to 0.75 inches expected for the
Brooks Range.

- A coastal storm approaches Monday bringing southerly winds and
additional rain Monday night through Wednesday night to the
Western Brooks Range and Chukchi Sea Coast
-IMPACTS: 2 to 4 foot water rises possible. Wave run up and minor
beach erosion possible.
-TIMING: Highest water expected Tuesday morning into Wednesday
north of the Bering Strait.

- Near normal temperatures with widespread highs in the 40s and
50s this weekend, warmer next week, in the 50s and 60s.

&&

.FORECAST ANALYSIS AND DISCUSSION...
As of Saturday morning a 530 dam upper level low sits over the
high Arctic north of Utqiagvik with a 539 dam low over the Norton
Sound. Beneath this upper level low sits a 998mb surface low over
the Baldwin Peninsula providing widespread showers to the West
Coast and Western Interior today. The upper level low will slowly
move through the pattern and drag the more widespread showery
conditions east into the Central Interior this afternoon and
evening along with cooler temperatures aloft. 850mb temperatures
fall as the low moves east down to -3F on the West Coast and
Western Interior with the strongest part of the low and to near 0
in the Central Interior. Fairbanks east remains above freezing,
bottoming out Monday morning near 1F. Calm winds are expected in
valleys overnight, but clouds and recent rainfall should prevent
strong inversions from forming. Should clouds begin to clear the
first frost of the season is possible in cooler valleys Monday
morning. Otherwise lows in the lower 40s expected Monday morning.

A slight ridge builds in the Eastern Bering Sea tonight and into
Sunday ahead of the next low moving through the pattern. The
ridging will mostly serve to push the showery conditions from this
first system east and provide a relatively dry day Sunday to the
West Coast ahead of an even wetter storm. This next storm is not
very strong ranging from 992mb to 998mb at the surface as it
approaches the West Coast, but it is very wet and fairly well
organized. Steady southerly winds are expected Sunday night
through Wednesday for most of the West Coast with High Surf
expected Monday through Wednesday along the West Coast south of
the Seward Peninsula. Heavy rains are expected during this time as
well due to another low moving along the Aleutians helping to pull
additional moisture from the Northern Pacific into this system. 1
to 2 inches is currently expected for most of the West Coast with
this event with the heaviest rainfall expected along the south
facing slopes on the Seward Peninsula and Western Brooks Range.


&&

.FIRE WEATHER...
No major concerns for the foreseeable future.

Showery conditions in the Western Interior today move east into
the Central Interior this afternoon and evening and reach the
Eastern Interior Sunday morning. Isolated thunderstorms are
possible amongst these showers on the east side of the low fueling
them. This would be in the Central and Eastern Interior today and
in the Eastern Interior Sunday. Behind these showers will be a
brief period of increasing pressure and drying Monday before the
next system in the overall pattern moves into the West Coast
bringing heavy rain and southerly winds to the West Coast and
Western Interior Monday afternoon through Wednesday. The Central
and Eastern Interior will see another round of strong southerly
flow ahead of the increased rainfall pushing areas just north of
the Alaska Range warmer and drier Tuesday and Wednesday before the
rain reaches Wednesday afternoon through at least early Friday.

&&

.HYDROLOGY...
Periods of moderate to heavy rain in Western Alaska will cause
notable rises to water levels through Wednesday, especially in the
Western Brooks Range and Southern Seward Peninsula, but due to
currently low levels no flooding is expected.

&&

.EXTENDED FORECAST DAYS 4-7...
Another push of cool and wet weather returns Monday afternoon,
bringing large amounts of rain into the West Coast once again. A low
pressure system out in the Bering Sea, coupled with a prolonged
period of southwesterly flow from a ridge situated over the
central/eastern Interior, will be the driving forces behind this new
pattern. This particular set up is known for presenting coastal
storm hazards along the southern Seward Peninsula and Norton
Sound, so we are monitoring conditions closely over the next
couple of days (more details below). Looking further into next
week, the large swath of precipitation is expected to reach the
central/eastern Interior beginning Wednesday, and continuing into
next Friday. The heaviest precipitation amounts are mainly for
the West Coast and western Interior, with the surrounding areas
experiencing mostly lighter stratiform precipitation.
Thunderstorms are not likely to occur with this system. During
this time, high temperatures will cool across the state into the
low 60s/upper 50s, with lows in the low 40s. A drier pattern looks
to creep back in by next weekend as another ridge tries to build
in from the southwest, however model agreement isn`t too strong as
of right now. For the time being, conditions look to bring us
closer to the Fall season.
- Santiago

Coastal Hazard Potential Days 3 and 4...
A coastal storm is expected Monday through Wednesday. Impacts
will begin on Monday south of the Seward Peninsula with water
rising around 2 to 4 feet above the normal high tide line Monday
afternoon through Wednesday morning. North of the Seward
Peninsula, impacts will begin Tuesday morning with water levels
also 2 to 4 feet above the normal high tide line. Winds will be
from the south/southwest with gusts potentially as high as 40 to
50 mph. Wave run up and minor beach erosion is expected from this.
Impacts persist into early Wednesday before winds shift northerly
as the storm moves east into the Western Interior late Wednesday.
These northerly winds do not last as long and impacts are expected
to be minimal.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...High Surf Advisory for AKZ821-822-824-825.
PK...Small Craft Advisory for PKZ802-803-853.
Small Craft Advisory for PKZ805>807-810-852-854-856.
Small Craft Advisory for PKZ808-855.
Small Craft Advisory for PKZ811-850-857.
&&

$$

Stokes
Extended- Santiago

750
FXAK67 PAJK 101408
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
608 AM AKDT Sun Aug 10 2025

.SHORT TERM...

Downward trend through this afternoon as the surface low has both
weakened into an open wave trough and has begun to push into
British Columbia. Behind the wave, ridging aloft is causing
pressure rises of around 1 mb per hour with predominantly westerly
wind aloft. This westerly wind is key to areas expected to have
the highest chances at rain this morning and afternoon. Looking
for west facing mountains to have the highest rain chances from
orographic lifting processes. However, looking at satellite, a big
swath of dry air is pushing in from the west as well, which will
erode away precipitation chances today. Therefore, highest chances
of precipitation are this morning, with accumulations less than an
inch.

Looking towards tonight, another surge of moisture looks to push
over the panhandle, primarily aimed between Port Alexander and
Elfin Cove to begin with, then sliding south through Monday
morning. For more information, see the Hydrology section.

.LONG TERM...
Key messages:
- Lingering light rain into Tuesday from a quick moving system to
start the week.
- Winds on a downward swing across the inner channels Tuesday/Wednesday.
- Ridge builds in the gulf through midweek with drier conditions
across the panhandle Tuesday and Wednesday.
- Rain to

Details: Continuing from the short term, the path of the fast moving
system on Monday will lead to increased winds in the inner channels
once more before gradually decreasing. Winds in the gulf will
pick up out of the southwest once more reaching up to strong
breeze (23 - 27 knots) before gradually dropping to fresh breeze
(17 - 21 knots) as a ridge builds over the gulf and flow along the
outer coast turns northwesterly.

This surface ridge coupled with an upper level ridge will bring
drier weather for Tuesday and Wednesday across the panhandle, along
with less cloud cover and warmer daytime highs up to around 70,
particularly for the southern panhandle. Model spread reigns
supreme for late next week, but as of this discussion, sometime
Thursday looks like when we can expect rain and cloud cover to
make their presence know again with a potential low forming in
the gulf.

&&

.AVIATION...Another Less than ideal flying weather day is
in store for SE AK, though conditions will at least marginally
improve in the afternoon across many locations. MVFR to IFR
conditions across the panhandle will experience some improvement
through the day in the wake of a system which departs in the
morning, and much of the panhandle will even experience a lull in
the rainfall through the afternoon. LLWS will generally drop off
through Sunday morning as well.

Starting late Sunday morning, winds will pick up and become gusty
for northern Lynn Canal, including PAGY & PAHN as a low moves
northeastward into the southern Yukon territory of Canada. This
will last through the end of the TAF period.

By late Sunday night though, another system will arrive, bringing
with it more moderate to heavy rainfall, as well as deteriorating
VIS and CIGS.

&&

.MARINE...
Outside: Downward trend in westerlies will continue through the
morning hours, sustained by the rising pressures in the wake of
the passing low pressure. As ridging aloft fully builds the
surface pressure, winds will diminish down to 10 knots. A warm
front will begin to push in from the SW tonight, increasing winds
back to a fresh to strong breeze from Sitka south. Fortunately,
the westerly swell which has been present will have subsided, with
wave heights becoming less swell dependent. Therefore, wave
heights will cap at around 9 ft coinciding with the westerly
winds, counter to the 13-14 ft seas currently on the coastline of
Prince of Wales Island.

Inside: Southerly winds continue to inundate the inner channels
from rising pressures. Widespread fresh southerly breezes will
continue through the morning hours before relaxing slightly and
shifting slightly westward. As the surface wave pushes into
Canada this afternoon, a shift in winds is expected in Icy Strait
to 20 knots from the SW. Only expect this to stick around for
around 6 hours as the warm front pushes in from the SW. Then,
stronger wind placement will shift to Chatham Strait, Stephens
Passage, Frederick Sound, and western Sumner Strait back up to 20
knots.

&&

.HYDROLOGY...

Rainfall will continue across the area as multiple systems move
into the panhandle through the weekend. As of Sunday morning,
heaviest rainfall rates are focused around west facing areas. In
particular, Sitka, Juneau, Petersburg, and areas near Wrangell
are the big winners, with 12 hour accumulations between 1.25 -
2.00 inches. Once more, the panhandle is on the downward trend;
however, Sunday night into Monday will see another plume of
moisture associated with a warm front move over the central
panhandle, then slowly shift southward. What is particularly
impressive about this moisture are freezing levels, which look to
exceed 12000 ft from Sitka southward. This combined with incoming
PW of 1.8 in, or about 180% of normal, will lead to heavy rain for
west facing mountains yet again. Fortunately for these areas,
ridging aloft will limit the amount of dynamic lift for areas over
the panhandle, which will limit overall rainfall. Unfortunately,
however, between the saturated air and very warm temperatures,
still looking at rising rivers and heavy rain. 1.5 - 2.25 inches
are expected, with higher amounts in west facing areas such as
Sitka. No changes with flooding -- no flooding is expected at this
time.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012-022-053-641>644-651-652-661>664-
671-672.

&&

$$

SHORT TERM...NC
LONG TERM....STJ
AVIATION...GFS
MARINE...NC
HYDROLOGY...NM

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