Crow Pass Trail, Alaska Weather Forecast Discussion

249
FXAK68 PAFC 300047
AFDAFC
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
447 PM AKDT Mon Sep 29 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through
3)...
Southcentral Alaska continues to sit under an upper-level col, an
area of relatively weaker flow between a trough sliding over the
Alaska Range and a deeper upper-level low over the southern Gulf.
This pattern has given way to generally quiet weather conditions
for most of the region. One exception is added cloud cover from
the eastern Kenai Peninsula northeast to the Copper River Basin. A
few scattered showers are also occurring along the Denali
Highway, closer to the upper-level trough.
As this trough moves east, the mix of rain and snow showers will
become a bit more widespread, especially across the Tok Cutoff
Road, from Slana north through Mentasta Pass. Light snow
accumulations, on the order of around an inch, are possible in
this area through Tuesday morning.
With clear skies and ridging building in from the west, patchy fog
is again possible from Homer north across the Anchorage Bowl and
into the Mat-Su Valleys. Overnight low temperatures will be
dependent on the timing and extent of fog; however, in places
where conditions remain generally clear with light winds, expect
overnight lows to again drop below freezing.
While model uncertainty into midweek remains high, the overall
synoptic picture remains quite similar. A front arrives to the
western Gulf early Wednesday morning with a surface low forming
in the northern Gulf later in the day. While there is some model
difference in the timing of onset of precipitation, it does look
like most places west of Prince William Sound will see some
precipitation by early to mid-morning Wednesday. The exact amount,
especially in the lee of the mountains, will be dependent on the
orientation of the flow aloft and the extent of southerly gap
winds. While uncertainty grows into Thursday, it it does look like
another round of precipitation will spread north across most of
Southcentral as the surface low tracks into Prince William Sound.
-TM
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days
1 through 3/Tonight through Thursday)...
Weather across the Bering Sea, Aleutians, and Southwest AK is very
quiet today under the influence of a short-wave ridge over the
central and eastern Bering. Subsidence along the eastern edge of
the ridge is leading to clear skies over Southwest AK. It was a
chilly morning with temperatures bottoming out in the 20s across
much of the Kuskokwim Valley and Delta, while communities in
Bristol Bay saw temperatures a bit warmer in the upper 20s to
mid 30s. Despite abundant sunshine, the lower sun angle and
decreasing daylight hours is noticeable, with temperatures slowly
rising through the 40s this afternoon. Meanwhile, a very weak
short-wave rounding the top of the ridge and associated surface
low are producing clouds and areas of light rain along the southern
Alaska Peninsula. A mix of sun and clouds and localized fog can
be found across much of the rest of the Bering and Aleutians.
Looking upstream, a high amplitude trough with closed upper low is
spinning over the Kamchatka Peninsula and far western Bering Sea,
gradually flattening out the upper ridge as it progresses eastward.
The low will march eastward to mainland AK on Wednesday. What is
now a weak surface low and frontal system will strengthen a bit as
it progresses eastward across the central Bering tonight and
toward Southwest AK Tuesday thanks to slight amplification of the
trough as strong vort-maxes rotate around the mainly upper low
circulation. This will result in fairly small areas of gale force
winds, primarily over the offshore waters of the Bering Sea, but
also with a brief peak of winds as the front reaches the Kuskokwim
Delta coast midday Tuesday. The front will cross Southwest AK
Tuesday afternoon through Tuesday night, bringing a fairly short
period of steady light rain. A showery regime will settle in
behind the front through Wednesday night as the upper low and
colder air move in aloft.
Meanwhile, the weak low currently near the southern Alaska
Peninsula will dissipate tonight as it tracks toward Bristol Bay.
This could bring some low clouds onshore along the Bristol Bay
coast late tonight. The tail end of the cold front with the
aforementioned Bering low will elongate and weaken along or north
of the Aleutians on Tuesday, with very little impact in the form
of rain or wind for the Aleutians. A deep low over the west
Pacific will track south of the Aleutian chain Tuesday night
through Wednesday. There has been a slight northward trend in the
track based on latest model guidance, so it now looks likely for
rain and wind along the northern periphery of the low to reach
the western to central Aleutians (Adak/Atka).
A short-wave trailing the Bering low will dig southward Wednesday,
leading to amplification of the upper flow. This will push the
cold front southeastward across the Eastern Aleutians and Alaska
Peninsula, leading to strong northwesterly gap winds Wednesday
night through Thursday.
Attention will then shift to a developing North Pacific low on
Thursday. Model guidance indicates phasing of subtropical and
arctic troughs, leading to a large and deep low tracking toward
the Bering/Aleutians as we head into the extended forecast period
(Thursday night and beyond). This storm has a good likelihood to
bring much greater weather impacts to the entire region.
-SEB
&&
.LONG TERM FORECAST (Days 4 through 7: Friday through Tuesday)...
The end of the workweek starts out with a Chukotsk low broadening
out into a trough of low pressure over northern and central
Alaska by Friday, with multiple weak embedded lows. Additionally,
a strong system approaches the western Aleutians, evolving into a
dominate Bering Sea storm. This system intensifies by Saturday,
sprawling across the Bering and moves towards Nunivak Island by
Sunday, possibly causing some minor coastal issues along the
Kuskokwim Delta with steady southwesterly onshore winds as this
system continues on towards Norton Sound before weakening sightly
at the of the forecast period. A separate low near the Kenai and
Alaska Peninsula Thursday weakens into a broad trough by Saturday
before being absorbed into the bering storm`s wind field by Sunday
and fully merges with it by Sunday and pushes a frontal system
into the western Gulf of Alaska by monday afternoon.
The major models predict the Bering Sea system over the weekend.
The European and Canadian models continue to be in agreement
trough day 7, with the CMC slightly stronger and faster. The GFS,
however, is still the slight outlier with its earlier forecast
period moderately different than its counterparts but improves
towards the end of the forecast period but still is not in full
agreement with the other 2. The Canadian is currently favored as
it leads the trend of the system moving south and east, ending up
weaker and closer to the Yukon Delta towards the end of the
period.
-DD
&&
.AVIATION...
PANC...VFR conditions, and light and variable to light northerly
winds, will persist. Given light winds and mostly clear skies
overnight, there is potential for patchy fog to develop along the
Cook Inlet and nudge into the terminal Tuesday morning.
&&
$$

NWS AFC Office Area Forecast Discussion