752
FXAK68 PAFC 130028
AFDAFC
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
428 PM AKDT Tue Aug 12 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...
A ridge of high pressure over Southcentral Alaska to continue
shifting eastward tonight, allowing for a front incoming from
Southwest Alaska to return to a cooler, more wet pattern. The
front will approach in the form of several shortwaves, each
bringing a chance for showers over areas of Southcentral beginning
first for Kodiak early Wednesday morning. By late Wednesday
morning, the front will shift over the Kenai Peninsula, initiating
showers largely across the mountains, Homer, and Seward. The
impact of this front over interior Southcentral has been a point
of focus for the forecast the last few days, however confidence is
growing towards a slightly drier push. As such, there is a chance
for light rain showers to develop for Anchorage Wednesday
afternoon and evening, peaking Wednesday night into Thursday
morning, however prolonged rainfall is not expected for the
Anchorage area with this system. The Susitna Valley will likely
see a more organized push of rain by Thursday morning. Chances for
rainfall from this system may persist into Thursday morning before
weakening and shifting eastward. Chances for rain in the Copper
River Basin to increase relatively by Thursday evening however
widespread showers are not expected.
-CL
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(Tuesday through Thursday)...
This afternoon, satellite imagery reveals an area of low pressure
near Gambell. Its attendant front is situated along the western
Alaska coastline, extending from Hooper Bay southward to the
Alaska Peninsula. Radar shows a swath of rain moving across
Southwest Alaska and the Alaska Peninsula. A High Surf Advisory is
in effect for the Kuskokwim Delta coast until 10PM AKDT tonight
for water levels 1 to 2 feet above the normal highest tide line
and waves upwards of 4 to 8 feet. Gap winds are still plaguing the
Eastern Aleutians with gusts up to 30-40 kts through favorable
bays and passes. The persistent onshore flow to the Kuskokwim
Delta and gap winds for the Eastern Aleutians will begin to relax
this evening as the front weakens and stalls over the area. Aloft,
there is a shortwave moving over the Pribilof Islands and a more
robust shortwave just off the Kamchatka coast embedded in a broad
longwave trough pattern.
Model guidance suggests that the combination of forcing from the
eastern most shortwave over the Pribilof Islands and an area of
disturbed weather tracking just south of the Eastern Aleutians
will lead to cyclogenesis Wednesday morning south of the Alaska
Peninsula and Kodiak Island. At the same time, a fast moving wave
of low pressure slides just south of the Central Aleutians with
some of the models showing the northern most area of its
precipitation shield clipping Adak and Atka. This feature exits
the region by Wednesday afternoon, with high pressure quickly
building in across the Bering with fog and low stratus in its
wake. Guidance diverges on timing of the next chance of
precipitation for the Western Aleutians. By Thursday or so, cold
air advection arrives from the northwest to Southwest Alaska,
keeping temperatures several degrees below average. Some models
like the GFS are showing a low pressure system arriving by
Thursday afternoon, and others like the Canadian-NH holding off
until some time on Saturday. The main forecast challenge looks to
be timing out the arrival of the aforementioned Kamchatka
shortwave that will move eastward over the short term. The airmass
over Southwest Alaska looks to modify some time this weekend,
returning the area to average temperatures.
-AM
&&
.LONG TERM FORECAST (Days 4 through 7: Saturday through
Tuesday)...
Saturday shows a ridge present in the Bering. This means more
fog/stratus for that region as well as calm winds and lower rain
chances. Northwest flow will allow for gap winds in the Eastern
Aleutians/Alaska Peninsula regions. These gap winds will last
until Sunday. Southcentral Alaska sees a col move in as an upper
level low exits to the southeast. This pattern continues through
next Tuesday. It is uncertain, but there may be some embedded
shortwaves passing through the ridge in the Bering which would
allow for some brief bursts of rainfall in the Aleutians. Even so,
weather should be mostly uneventful through Tuesday. Southcentral
will also be on the quieter side as slack flow remains in place
through Tuesday. Wednesday sees a longwave trough push in from the
west. This could mean higher rain chances as well as gusty winds
not only in the Bering, but also the Southwest mainland, and even
into Southcentral. Uncertainty remains high with this scenario,
which may change on a whim.
-JAR
&&
.AVIATION...
PANC...VFR conditions and light winds will persist. Some model
guidance brings in a brief period of gusty S-SE winds this
evening. However, based on the pattern, am discounting this and
sticking with a more traditional sea breeze direction and lighter
winds. A weak upper level short-wave will move up Cook Inlet on
Wednesday, but expect most (if not all of the rain) to remain to
the south. Even if rain does make it into the terminal, expect
ceilings to remain VFR.
-SEB
&&
$$
427
FXAK69 PAFG 130014
AFDAFG
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
414 PM AKDT Tue Aug 12 2025
.SYNOPSIS...A coastal storm continues along the West Coast with
heavy rain and high surf. Issued a Flood Watch for the southern
Seward Peninsula this shift for high water across rivers draining
the Bendeleben Mountains. Nearly 2 inches of rain has fallen north
of Nome in the last 24 hours, and up to 1.5" northeast of
Kivalina. Clouds and precipitation will move east through the
week, though rainfall amounts will be much less in the Interior.
By Friday, much needed rainfall is expected across the Upper
Tanana Valley.
&&
.KEY WEATHER MESSAGES...
Central and Eastern Interior...
- Temperatures warm Tuesday and Wednesday with highs in the upper
60s to low 70s.
- A brief period of gusty southerly winds through Alaska Range
passes expected Tuesday night into Wednesday morning with gusts
up to 30 mph possible. Stronger gusts expected further west.
- Additional rainfall expected later this week arriving from the
West late Wednesday and lasting into the weekend. The heaviest
rain is expected Thursday and Friday.
West Coast and Western Interior...
- Bering Sea Storm through Wednesday morning.
IMPACTS:
-2 to 4 feet water rises possible, highest in the Norton Sound.
-Wave run up and minor beach erosion possible.
-Heavy rain expected Monday through Wednesday with 1 to 2 inches
expected along the West Coast and 2 to 4 inches possible along
south facing slopes on the Seward Peninsula and the far Western
Brooks Range, heaviest west of Kiana.
-Rivers/streams expected to see notable rises in water level.
-Winds weakening overnight Tuesday night and turning northerly
through the Bering Strait.
TIMING:
-Highest water levels expected through Wednesday morning. Two
peaks are expected, the second higher peak will be Tuesday
evening.
-Heavy rain expected through Wednesday.
North Slope and Brooks Range..
- A coastal storm approaches Monday brings rain through Wednesday
night to the Western Brooks Range and Chukchi Sea Coast
IMPACTS:
-2.5 to 3.5 feet of water rise above the normal high tide at
Point Hope. Around 2 feet of water rise for Point Lay.
-Wave run up and minor beach erosion possible.
-Heavy rain in the far Western Brooks Range with estimated totals
of 2 to 4 inches, heaviest west of Kiana.
-Strong south winds through Brooks Range Passes with gusts up to
40 mph possible at Anaktuvuk Pass and up to 35 possible at
Atigun Pass.
TIMING:
-Highest water expected into Wednesday north of the Bering
Strait, with the peak having occurred Tuesday morning.
-Heavy rain in Western Brooks Range expected through Wednesday
-South winds increase peak Tuesday, and diminish Tuesday night.
- Cooler temperatures warm Tuesday with highs rising into the mid
to upper 50s Monday and into the 60s Tuesday. Temperatures cool
back into the upper 40s to lower 50s in the latter half of the
week.
&&
.FORECAST ANALYSIS AND DISCUSSION...
The upper-level flow pattern continues to exhibit a dipole across
Alaska, with ridging and high pressure over the eastern portions of
the state, and troughing with general storminess and low pressure
across the western part of the state. Embedded in southwesterly flow
downstream from the trough axis, a stream of moisture and embedded
mid-level disturbances will continue their onslaught on the West
Coast bringing periods of heavy rain, and gusty winds of 25-35 mph
today and tonight. Widespread rainfall amounts of half an inch to an
inch are likely across an area from the Yukon Delta, northward into
the western North slope. Local terrain enhancements in southern
portions of the Seward and Lisburne Peninsulas may result in
rainfall totals as high as 2 inches by tonight. This will bring the
potential for minor flooding along small creeks and streams through
Friday morning.
Across the eastern two-thirds of Alaska, high pressure today will
keep conditions warm and sunny, with highs ranging from the upper
60s to the low 70s. Upper-level clouds will stream into this region
from the west today and tonight as the disturbance in the North
Bering Sea slowly moves onshore.
The storm system impacting West Alaska today will slowly move east
over the course of this week, periods of rain to most of Central and
Northern Alaska through Thursday. Increasing cloud cover after today
will also act to moderate temperatures, keeping highs starting
Thursday in the upper 50s/lower 60s. The one exception to this trend
will be the upper Tanana Valley and Yukon Flats, where temperatures
may reach into the low 70s again tomorrow before the arrival of the
aforementioned storm system. Given prevailing southerly flow at the
surface ahead of this system, subsidence downstream from the White
Mountains will also act to minimize the amount of precipitation in
the Yukon Flats, keeping this area substantially drier than
surrounding areas.
&&
.FIRE WEATHER...Very wet conditions continue across the west coast
as a strong frontal system pushes east. This system will weaken
quickly as it moves inland, but will still bring showers to the
Interior on Thursday. The system will stall over the eastern
Interior as a low moves into the eastern Gulf of Alaska and looks
to finally provide much needed wetting rains to the Upper Tanana
Valley Friday and Saturday. Until then, RHs will remain down near
30% for minimums east of Delta Junction, with Wednesday being the
driest day. Thunderstorms are not expected over the next week.
Brief periods of southerly gap winds gusting to 30 mph expected
through Wednesday night.
&&
.HYDROLOGY...Periods of heavy rainfall through Wednesday in Western Alaska
will cause notable rises to water levels, especially along the
southern Seward Peninsula and far Western Brooks Range where 2 to
4 inches of rain is expected throughout the event. Rivers sourced
in the far Western Brooks Range are expected to rise
significantly to near bankfull with a chance for minor flooding.
Impacts will be limited by lower water levels ahead of the event.
A Flood Watch is in effect for the southern Seward Peninsula.
The main river of concern is the Niukluk River. A Hydrologic
Outlook also provides more details on heavy rain in the Western
Brooks Range.
&&
.EXTENDED FORECAST DAYS 4-7...
...Friday and Saturday...
Upper-level troughing is expected to generally prevail across much
of the state for the beginning of this weekend. This pattern will
bring widespread cloudiness with isolated (20-30%) light rain
showers. However, there will be two areas of enhanced precipitation
chances.
The first area will extend from the Eastern Interior northwards to
the Eastern North Slope. A meridional-oriented filament of mid-level
vorticity will act to bring enhanced lift into this region,
resulting in more widespread (50% chance) light rain. With
temperatures Friday night into Saturday potentially dropping into
the lower-30s and upper-20s, light snow is possible in the higher
elevations of the Brooks Range and the far Eastern North Slope,
including the Dalton Highway through Atigun Pass.
The second area will primarily encompass the Seward Peninsula,
Lisburne Peninsula, and adjacent areas in the Western Interior and
North Slope respectively. Medium range guidance is in general
agreement of a shortwave trough ejecting out of far Northeast Russia
and quickly moving east across the North Bering Sea/South Chukchi
Sea. Forcing for ascent ahead of this disturbance will bring a
rather large area of scattered rain showers (50% chance) into this
region Saturday into Saturday night. Low-level flow looks to become
southerly in advance of this disturbance, supporting locally
enhanced rainfall rates/amounts along any southward facing slopes.
High temperatures during this time should range from the upper 50s
to the low 60s, with lows in the upper 30s and low 40s, slightly
below climatological average.
...Sunday and Monday...
By the second half of the weekend and into early next week, upper-
level ridging and southwest flow builds into much of Southern and
Central Alaska, with troughing over the Chukchi and Beaufort Seas
bringing west flow across the Brooks Range and North Slope. This
flow regime will help bring moisture into the interior, with general
cloudiness and isolated rain showers. Conditions on the North Slope
will be more harsh, with gusty winds out of the west/northwest and
overcast, with periods of fog and/or drizzle. Model solutions begin
to diverge with the timing of the northern system during this time
frame, with the GFS more progressive than the Euro. Regardless, the
weather pattern should generally be unsettled across much of Central
and North Alaska, with periods of rain and slightly below normal
temperatures (highs primarily in the 50s and low 60s in the lower
elevations).
Coastal Hazard Potential Days 3 and 4...High surf receed Wednesday as
winds shift north along the West Coast. Expected impacts days 1
and 2, please see Key Weather Messages.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
AK...High Surf Advisory for AKZ821-822-824-825.
Flood Watch for AKZ822.
PK...Small Craft Advisory for PKZ801-802-804-808-811-855-858-859.
Small Craft Advisory for PKZ803-809.
Small Craft Advisory for PKZ805-807-810-853-856.
Small Craft Advisory for PKZ806-854.
Small Craft Advisory for PKZ816.
Small Craft Advisory for PKZ817.
Small Craft Advisory for PKZ850.
Small Craft Advisory for PKZ852.
&&
$$
Chriest
Analysis/Extended: Darrah
937
FXAK67 PAJK 130632
AFDAJK
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
1032 PM AKDT Tue Aug 12 2025
.UPDATE...to update both the aviation & hydrology sections...
&&
.SHORT TERM...As of Tuesday afternoon the precipitation and majority
of upper level cloud cover has departed the panhandle. Aside from
some orographic induced clouds from the now predominantly
northwesterly flow aloft, skies will remain relatively clear of
significant cloud cover through the evening hours. Overnight
Tuesday into Wednesday, a marine layer is expected to reform along
the gulf coast. Similar to Monday night, some of this is expected
to filter in around Cross Sound once more with drops in
visibility through the morning hours and subsequent clearing with
daytime heating and turbulent mixing. For communities in the inner
channels, clearing will allow for radiational fog to develop.
Heading into Wednesday, the panhandle will continue to see
overall clearer conditions once any marine layer stratus or
radiational fog dissipates by mid to late morning. As a result,
daytime maximum temperatures will be a bit warmer across the
region, with many areas reaching the low to mid 70s. This will
also allow for more localized afternoon sea breezes to develop,
however these are not expected to be particularly strong.
For information on ongoing flooding in Juneau, check out the
Hydrology section below and check out the latest flood statement
at weather.gov/juneau.
.LONG TERM.../ Thursday to Sunday / The ridge aloft is moving east
and closed low is forming in the bottom of the trough headed to the
Southeast gulf and eventually be Southwest of the Haida Gwaii by
Friday evening. The track of the low will likely keep any of the
rain showers to the southern half. As the low becomes more
vertically stacked, more showers will be moving from BC into the
southern and then central panhandle Friday and Saturday.
The afternoon and evening showers Friday and Saturday and possibly
summer doesn`t not include the stronger convection which would mean
the mention of thunder. Will watch this to see if it will be needed
to be added.
Temperatures Thursday overall at or warmer than normal, and the
southern panhandle cooling a bit as the clouds and rain spread in.
Northern section may be close to 70 degrees Friday. Weekend highs
around normal highs.
&&
.AVIATION.../Until 06Z Thursday/...From light winds & clearing
skies giving good conditions for radiational cooling over a good
portion of the Panhandle in addition to plenty of SFC moisture
in place over the region from recent heavy rainfall, areas of FG
are anticipated, late tonight into Wednesday morning. As for SFC
winds, they generally look to remain on the lighter side as the
pressure gradient remains relatively relaxed through the TAF
period under the area of high pressure that is building into the
region. As we have clearing skies over SE Alaska through the
period, some relatively enhanced afternoon sea breeze winds are
anticipated for areas prone to those. LLWS will remain benign
through the period.
&&
.MARINE...
Outside: With rising pressures in the northern and central gulf,
winds in the eastern gulf have shifted out of the NW and increased
to moderate to fresh breeze (11 - 21 knots). With very light SW
swell, expecting wave heights continue a downward trend Tuesday
night and through most of Wednesday. Tonight will see a marine
layer develop, bringing low clouds and dropping visibilities down
to one mile, particularly near Cape Spencer.
Inside: With the trough digging south to southeast and a ridge
building north and west of the panhandle, this has lead to a
mostly light to northerly wind pattern for the inside waters for
Tuesday. Several locations look to be impacted with increased
winds as the trough digs, mainly east west channels. Icy Strait
and Cross Sound, in particular, will continue to have increased winds
from a tightening gradient to 15 to 20 knots through Tuesday
evening before relaxing later Tuesday night. Similarly, eastern
Frederick Sound zone just north of Petersburg and Sumner Strait
look to see a brief increase in westerly winds to a moderate
breeze (11 to 16 knots).
&&
.HYDROLOGY...SUICIDE BASIN IS RELEASING. CREST HEIGHT IS EXPECTED
BETWEEN 8 AM TO 12 PM WEDNESDAY.
A Flood Warning for the release of Suicide Basin remains in
effect. USGS laser gauge data from Suicide Basin and Mendenhall
Lake levels indicate a sub-glacial release from the basin is
continuing. As of 10 PM AKDT, Mendenhall Lake is currently in
Moderate Flood stage at 13.0 ft & is approaching Major Flood
Stage. It is forecast to cross 14 feet (Major Flood Stage) at
around 1 AM. The crest height is still expected on Wednesday
morning between 8 AM & Noon, reaching near-record levels between
16.3 and 16.8 ft. The reporting gauge is at Mendenhall Lake. So
expect the crest to make it downstream 15 to 45 minutes after the
lake crests, with respect to how far you are located downstream.
Be aware that some riverbank erosion, trees, & other debris
floating down the river have already been reported. Review the
published Flood Warning for more information, as that will be
continuously updated.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...None.
&&
$$
SHORT TERM...STJ
LONG TERM...Bezenek
AVIATION...JLC
MARINE...STJ
HYDROLOGY...JLC
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