Small Craft Advisory 355, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
456 PM AKDT Wed Apr 27 2022

.ANALYSIS AND UPPER LEVELS...

The upper level ridge over Southwest mainland Alaska is weakening
as an upper level low over northern Alaska rotates southward into
it and a stronger low moves in from the west. At the surface,
high pressure remains over mainland Alaska though the center of
the high is well into the Arctic. A front stretching from the
eastern Aleutians through the northwest Bering Sea is pushing into
the ridge and that is making it slow to advance.

There is still very little afternoon cumulus in Southcentral
Alaska even with some colder air aloft. It is a similar situation
in Southwest, though there is some cumulus building around the
western slopes of the Kuskokwim and Kilbuck Mountains, as well as
lower elevations around Bristol Bay.

&&

.MODEL DISCUSSION...

Models are again in good synoptic agreement with the main issues
being handling of the weak upper level waves over Southcentral.
Recently, these features have been shown a bit too strong, so
that is something to take into consideration when looking at the
light showers that models generally show developing over the Kenai
Mountains overnight and drifting northward to the Mat-Su tomorrow
morning. Basically almost every model shows some weak showers
moving through, but the exact track and timing differs so it will
remain just a slight chance for a shower at any given location.
Things settle down with the models as they are in good agreement
with the series of lows that will track through the Bering tonight
through the weekend. The strong front that will move into the
Gulf Friday and Saturday also seems to be handled well and the
strength of this system is bringing the models in better agreement
as there are no longer those weak short waves to deal with over
the area by Friday and into the weekend due to the strong low and
front.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.

&&

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

Increasing clouds are expected overnight as a weak shortwave is
expected to move into the area from the south. While there is
only a chance of showers with this shortwave, the current
satellite over the Gulf where it is originating does not show much
lift associated with it. So even though models are indicating it
could produce showers overnight into Thursday morning, it is hard
to get too excited about it at this time. It may just make it a
little more cloudy Thursday than the past few days.

The main change in the weather will be on Friday and into Saturday
for Kodiak as a front moves over the island Friday and then stalls
over the area through Saturday. This will bring gusty easterly
winds as well as rainfall. This low will then track south of
Kodiak with higher pressure over Southern mainland Alaska so most
of Southcentral will still just see some limited clouds with this
front with the north Gulf coast being about the only place other
than Kodiak that may see some rain with this system.

&&

 .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3/Tonight
through Saturday)...

Ridging weakens over the eastern Bering Sea this evening as
longwave troughing over the western Bering Sea pushes eastward
into the weekend. South to southeasterly winds increase through
the day Thursday and become gusty as a front moves east.
Initially, winds will be strongest along the coast and the AKPen;
however, once the front moves over land, winds further inland will
follow suit. Precip associated with the front will be confined to
the southern AKPen, from False Pass to King Cove beginning
tonight, before spreading east to Pilot Point Thursday. A second
front moving east Thursday night and Friday will bring another
round of strong southerly winds resulting in another round of gale
force winds for the eastern Bering Sea and along the coast
Friday. Precip spreads east and increases in coverage Friday with
the second frontal approach and passage.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3/Tonight
through Saturday)...

Longwave troughing remains over the central and western Bering
Sea through the weekend while ridging weakens over the eastern
Bering. Precip will diminish across the eastern Aleutians this
evening and tonight as a front pushes east to the AKPen. South to
southeasterly small craft winds prevail through Thursday evening.
A low dropping from the Kamchatka Peninsula to the western
Aleutians by Thursday night will push an associated front across
the western Aleutians Thursday morning. As this front pushes east
across the Aleutians, it will bring areas of southerly gale force
winds through the gaps and passes of the southern AKPen by early
Friday morning, while winds across the western Aleutians take on a
more westerly component. Gale force winds will become more
widespread across the eastern Bering Sea, including Bristol Bay,
and areas south of the AKPen throughout the day Friday. Widespread
precipitation spreads eastward Thursday into Friday with the
passage of the front.

&&

.MARINE (Days 3 through 5: Saturday through Monday)...

Gulf of Alaska: High pressure exits the Eastern Gulf for Sunday.
A low forms over the Southern Gulf early Sunday and remains nearly
stationary. Its front anchored by the low extends across the Gulf
through Monday. Forecast confidence is good. Increasing winds
with the front become widespread high end gales, wrapping the low
and diminishing Monday. Seas to 12 feet, subsiding.

Bering: A Central Bering low merges with the Gulf low on Sunday.
A strong North Pacific low and front tracks over the Aleutians
through Monday. Forecast confidence is fair, but decreases with
the track of the Western Low through Monday. Gusty Easterly winds
over the Northern Bering diminishes by Sunday. Seas to 12 feet,
subsiding. Gusty winds increase to high end gales wrapping the
Western low as it move to the Eastern Aleutians for Monday. Seas
to 16 feet on the Pacific side of the Western Aleutians subside
Saturday, then build to 22 feet along the Pacific side of the
Central Aleutians through Monday.

&&

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

Looking ahead in the extended forecast, the latest operational
model runs are in decent agreement with the evolution and
progression of the synoptic scale features, but begin to diverge
in the specific details towards the end of the period. For
Southcentral, a front extending ahead a Gulf low maintains
precipitation along the coast on Sunday, while inland valleys
remain relatively dry due to downslope flow. By Monday, another
front associated with a secondary low tracks along the north gulf
coast, keeping the wet pattern going through the middle of next
week. Out west, a North Pacific low approaches the Western
Aleutians late Saturday, with the attendant front bringing rain
and gusty winds across the Chain and Bering Sea through early Tue.
The strongest winds stays south of the forecast area as the main
center of the low exits out of the area. By the middle of next
week, benign conditions can be expected a weak ridge of high
pressure builds overhead.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AFG
MARINE/LONG TERM...MK/MF