474
FXAK68 PAFC 171433
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
533 AM AKST Fri Jan 17 2025

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

The next weather system is moving into Southcentral today with
rain already starting in Kodiak and Homer early this morning and
cloud cover elsewhere across the region. Satellite imagery shows
the main low in the northern Bering Sea and a very long front
extending from the low to near Kodiak Island and then southward to
just east of the Hawaiian Islands. While this is a very far
distance to advect warm southerly air, there are a number of
factors which will mitigate the amount of warm air it brings into
Southcentral. The first can be seen in satellite imagery where
there is more of a southeast direction to the front instead of
due south. There are also a number of places where there are
`bends` in the front which can act as places for a triple point to
develop and diminish the warm air advection to a degree. This is
what is expect to happen for Saturday when a triple point low
develops along this front and moves into the Gulf of Alaska. While
500 mb winds will still be south-southeast, as one works down the
air column it will turn southeast and then nearly east at the
surface along the north Gulf coast. The result is that while it
will warm up some, and warm above freezing in a number of
locations, there is more cold air available to keep areas of
Prince William Sound snow into Saturday. Inland areas will likely
not see any precipitation through Saturday as the cross- barrier
flow remains too strong. A mild weekend again, but not nearly as
warm as last weekend.

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA AND THE BERING
SEA/ALEUTIANS (Friday to Sunday)...

A 977mb low currently in the southern Bering Sea just north of
Adak, will merge with a second North Pacific low Friday morning
in the vicinity of the Pribilof Islands. These lows will bring
precipitation and strong winds to the Aleutians, Alaska
Peninsula, and Southwest Alaska. Coastal flooding will be
possible along the Kuskokwim Delta coast. Both a winter weather
advisory and a coastal flood advisory remain in effect.

The location and timing of the parent 977 mb low has been well-
handled by the models in comparison with surface and marine
observations. Gusts in the Alaska Peninsula and along the
Southwest coast have ranged from 20 to 30 knots. Wind gusts in
these areas ranged from 40 to 60 knots overnight but diminish
today. Snow will continue to change to all rain in Southwest
Alaska this morning as temperatures continue to increase.

The formation of a 987mb low south of Sand Point late Saturday will
cause a resurgence of southeasterly wind through the Aleutian
bays and passes then into the Southwest coast. Widespread gusts
for the weekend ranging from 35 to 45 knots though through bays
and passes while for the Kuskokwim Delta coast, gusts could reach
as high as 60 knots Saturday morning. These winds could increase
the likelihood of flooding.

Sunday morning will see the arrival of a front belonging to a 985
mb North Pacific low to the western Aleutians. Model consensus
has yet to determine if the front extends as far north as, and if
the strongest area of precipitation ascends on the east or west
side of, the Pribilof Islands. Cold air aloft between these
systems is drawn eastward across the Bering Sea, possibly changing
rain to snow for the Pribilofs.

&&


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

Starting off the long term is an unsettled pattern in the Gulf of
Alaska. Moderate precipitation will affect most of the Gulf coast
and the coastal mountains. Western Kenai and the Anchorage
regions, however, will remain mostly dry due to a lack of forcing
despite less downsloping. A surface low will track into the
northern Gulf by Monday afternoon, bringing another burst of
precipitation mostly into the Gulf coast and coastal mountains
once again. It is a bit uncertain if any precipitation will make
it into the Anchorage region and will depend on the track of the
low. Temperatures will be near or below freezing closer to the
coast so snowfall or rain/snow cannot be ruled out even at the
coast with areas further inland having better chances for snow.
Looking west, an upper low with a complex of surface lows moves
into the western and central Aleutians, bringing gusty winds up to
gale force and chances for snowfall or rain/snow as cold air
wraps around the back end of the complex from the north. The
complex will traverse eastward into the mainland late Monday into
Tuesday, increasing precipitation chances and winds there as well.
Warm air advection will keep temperatures above freezing in
Bristol Bay and The Kuskokwim Delta, but temperatures aloft should
stay cold enough to prevent freezing rain. The low complex will
elongate as it moves into the mainland, so precipitation chances
and winds will slowly diminish into Wednesday.

Ridging builds into Southcentral on Tuesday, which will drop off
precipitation chances all across the region. Come Wednesday,
a frontal boundary from the elongating low complex out west will
move into Southcentral. Winds speeds and precipitation chances
will increase in response. This will be further reinforced by an
upper low with associated surface low tracking up the Gulf by
Wednesday night into Thursday morning. However, other guidance
has a weaker surface low with just an upper level trough instead,
so depending on which guidance is correct, more or less
precipitation and winds will occur. Regardless of which scenario
is correct, expect increased winds and precipitation for the Wed-
Thu time period for Kodiak Island and the Gulf coast. For the
Anchorage region, again, precipitation chances will depend on the
track of the low. Out west, A period of riding will build in
Wednesday into Thursday, calming winds down and decreasing
precipitation chances until a shortwave drives into the western
and central Aleutians by Thursday morning, driving gusty winds and
increased precipitation chances which may or may not start off as
snow depending on how much cold air is still in place.

-JAR

&&.AVIATION...

PANC...Light north to northwesterly winds at the surface with
southeasterly winds aloft will contribute to continued low-level
wind shear through Saturday. Ceilings remain VFR with only a low
chance for ceilings to lower below 5000 ft at times.

Quesada

&&


$$