Gale Warning 796, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
449 AM AKST Tue Nov 5 2024

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

A strong front extending east off of a low in the eastern Bering
is currently over the Kenai Peninsula. Moderate to heavy
precipitation has been measured from Kodiak north to Whittier.
High winds have been observed through the Turnagain Arm already,
with Portage measuring a 70 mph gust and gusts ranging from 30 to
50 have been observed along the Seward Highway through Turnagain
Arm. Winds are just starting to tick up along the Anchorage
Hillside, where a brief but very strong period of wind is expected
around the time of frontal passage (8-10am). During this time
strong winds may also funnel through the gaps into Anchorage,
particularly along the weigh station of the Glenn Highway and into
south and west Anchorage. Additionally, winds have been steadily
increasing through the Mat and Knik Valleys with gusts in the 40
to 50 mph range expected. Despite the strong cross-barrier winds,
some precipitation has been successful at making down to sea
level. Soldotna and Anchorage have been observing some light
precipitation, snow in Anchorage and rain in Soldotna, as of 4am.
With the frontal passage, Anchorage will quickly warm into the 40s
and any remaining precipitation will change over to rain, however
amounts will a trace up to a few hundredths. Most areas are
expected to warm above freezing due to southerly winds and
cloud cover. Areas that still have snow-cover on the roadways may
have difficult driving conditions as things melt.

After the front moves through, showery and breezy conditions are
expected. Generally southerly flow will mean that areas like
Seward, Valdez and Cordova will get the brunt of the
precipitation, but a few errant rain showers can't be ruled out
for Cook Inlet communities and the southern Mat-Su. This will
persist through Wednesday before another storm moves south of
Kodiak on Thursday. This will reorient the wind field and may help
to bring most inland areas back below freezing for the overnight
period, or close to. This storm will be another mostly rain and
upper elevation snow event for Kodiak and the Gulf coast. Little
to no precipitation is expected in the lee of the mountains.

&&

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

A storm force low continues tracking north towards Cape Newenham
today, pulling strong winds and warmer air into interior Bristol
Bay. Transitions from rain to snow have been steadily working west
across Bristol Bay, with Dillingham and having switched overnight.
Cape Newenham and Platinum are entering into a rain/snow mix but
are expected to become all rain by early this morning. Further
inland areas near Koliganek are also expected to become all rain
by early this morning.

Blizzard conditions are expected to continue across the Kuskokwim
Delta coast this morning and begin to gradually wind down through
this afternoon.

&&

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

A low will be near Kodiak Island on Friday. This low will drive
near gale force winds for the waters around Kodiak island
especially in Shelikof Strait, the Barren Islands, and Kamishak
Bay. Kodiak Island will experience a short period of moderate
rainfall before the low exits the area. No snowfall is expected at
sea level with this low due to a warmer airmass from southerly
flow. Inland areas will likely remain calmer and drier due to
moisture remaining wrapped up in the compact low further south.
There is some uncertainty with the track of this low with some
models having it more to the east and others having it over west
over Kodiak Island. Impacts may be different depending on where
the low ends up tracking.

Looking to the west, another low will arrive in the North Pacific
on Friday. This low will track eastward south of the Aleutian
Islands. The low will bring gale force winds with some potential
for storm force winds to the Aleutians as it tracks eastward. It
will also cause moderate rainfall. This low will eventually
traverse to the Gulf of Alaska by Sunday. Here is where much
uncertainty arises. Most models disagree on its track and strength
with the GFS being the most bullish and the ECMWF being the
least. Ensembles are similar in disagreement with a very high
spread between the members. Looking at a middle ground solution
would allow for strong gale force winds with a potential for storm
force winds to have some impacts for the waters east of Kodiak
Island. However, the low may track too far south for any
significant impacts further north. The Southcentral coastline will
only experience moderate rains and small craft winds. Inland
areas including Anchorage will remain mostly dry with lighter
winds.

The end of the long range period on Monday reveals another low
passing through the North Pacific south of the Aleutian Islands.
Like the previous low, it will track eastward and allow for gale
force winds to affect the Aleutians. Colder air ahead of the front
allows for a potential for mixed precipitation in the Aleutians
as the front moves east. Looking at the Bering, a very cold air
mass exists near Russia. Some models are picking up on a
possibility of a polar low forming in the north Bering due to
baroclinicity between the two air masses.

-JR

&&

.AVIATION...

PANC...A major storm system will impact southern AK through today.
The main impact to the terminal will be winds and significant low
level wind shear. As the front nears Anchorage between 12Z and
18Z this morning, gusty northwest winds will develop at the
surface while southeasterly winds strengthen above the surface.
This will lead to a period of low level wind shear within 500 feet
of the ground, with the worst shear expected from about 15Z to
19Z. As the front then passes through around 20Z, surface winds
will shift to southeasterly and become gusty as a much weaker
Turnagain jet bends into west Anchorage. This will also cause
temperatures to shoot up into the lower 40s. After a brief lull
in the mid-afternoon, another round of gusty southeasterly winds
is expected from this evening through Wednesday morning as
pressure gradients tighten in response to the low center moving
towards 60N latitude.

As for precipitation, the strong flow across the mountains
typically leads to downslope drying and high ceilings. In this
case, the upper level dynamics are strong and moisture content of
the system is high, which will likely lead to a brief period of
light snow between 12Z and 18Z this morning. With a warming
airmass, a mix with rain is also possible. In any case, the most
likely scenario is that both ceiling and vis remain in the VFR
category, with lower conditions more likely for east
Anchorage/front range Chugach. Worst case scenario, there could be
a brief period of MVFR conditions.

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
112 PM AKST Tue Nov 5 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0830 AM     Snow             5 E Valdez              61.11N 146.22W
11/05/2024  M1.7 Inch        Chugach            AK   Public

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
144 PM AKST Tue Nov 5 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0132 PM     Snow             5 E Valdez              61.11N 146.22W
11/05/2024  M1.9 Inch        Chugach            AK   Public

            Calm wind and 32 degrees F. Snow flakes are
            becoming small and look like little hail
            stones. Wet snow.

&&

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