Kenai, Alaska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

898
FXAK68 PAFC 061252
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
452 AM AKDT Sun Oct 6 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Today
through Tuesday night)...

A large upper level low circulation continues to be the dominant
feature affecting Alaska. However, a new low which developed
yesterday in the north-central Pacific has become the dominant
low. It is tracking into the southwestern Gulf this morning,
while the original low weakens as it drops south across the
Alaska Peninsula and gets absorbed into the circulation of the
newly developed low. An occluded front draped east-west across
the southern Gulf will rotate north and west across the Gulf
today, leading to increasing winds across the Gulf waters as well
as Cook Inlet and Shelikof Strait. Based on observations overnight
and the impressiveness of the low in satellite imagery, have
generally upped the marine wind forecasts by 5 to 10 kts across
the board.

Meanwhile, a host of short-waves continue to rotate around the
still very large cyclonic circulation aloft. One short-wave which
brought showers to Anchorage and parts of the Mat-Su yesterday is
now exiting across the Western Alaska Range to the Kuskokwim
Valley. However, additional short-waves continue to stream in
from the southeast, with widespread showers being observed across
the northern Gulf and Prince William Sound regions. To the east of
the low center, a jet streak is tracking northward across the
central to eastern Gulf, driving short-waves northward toward
eastern Prince William Sound and the Copper River Basin. The
heaviest rain will be shunted eastward toward the northeast Gulf
coast and Southeast Alaska. However, some rain will spread
northward into the Copper River Basin tonight through Monday. Snow
levels over Southcentral will gradually fall over the next couple
days. Thompson Pas, which has seen some falling wet snow, will
likely see some light accumulation on the roadway. Other passes
surrounding the Copper River Basin could also see periods of wet
snow, including Tahneta Pass/Eureka, Paxson to Isabel Pass, and
Mentasta Pass.

Model guidance displays a fairly large spread in the ultimate
track of the low across the Gulf tonight through Monday night,
leading to uncertainty in the wind and precipitation forecast.
However, the general trend will be for the low to exit eastward
with diminishing precipitation across Southcentral and Kodiak
Island. The upper level pattern becomes quite messy by Tuesday,
with the remnants of a trough, a short-wave ridge, and a new
weakening trough approaching from the west. This will likely
maintain significant cloudiness across the region (with some
breaks), but little in the way of precipitation by Tuesday. Cold
air advection will accompany the arrival of the short-wave trough
in the western Gulf Monday night through Tuesday, leading to
strengthening gap winds along the Alaska Peninsula and across
Kodiak Island and the western Gulf.

-SEB

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA, AND THE BERING
SEA/ALEUTIANS...

A large low, recently spanning the eastern Bering and coastal
Southwest Alaska, departs to the south from Cold Bay this
morning. In its wake, a swath of cold midlevel arctic air (minus
10 Celsius) will be drawn south across the Bering Sea. Northerly
winds will increase again across the eastern Bering Sea from
Nunivak Island and the Pribilofs south to the eastern Aleutians
and the Shumagin Islands. Locations such as Cold Bay can expect
northerly winds with gusts of 40 mph likely during the morning
hours on Sunday and Monday. There is moderately low confidence on
the exact peak magnitude of the wind gusts, however, cool, dense
air could become enhanced through gaps, bays, and passes.
Generally drier weather is expected for Southwest Alaska, as
precipitation will likely be limited to prominent terrain.

Meanwhile, over the western Bering, high pressure will continue
to build through Monday morning before dipping south of the
Aleutians ahead of two lows, one from Russia and one from Japan.
Monday afternoon, the low out of Russia will swing through the
northwestern Bering. Its front and associated precipitation will
weaken Tuesday morning between Saint Matthew and Nunivak Island.
Although there will be relatively warmer air advecting into the
area, a few snowflakes cannot be ruled out for the Pribilofs and
Saint Matthew Island. On Tuesday, the incoming system from Japan
to the western Aleutians will be much warmer at the midlevel (0 to
4 Celsius). Although there is some model spread concerning the
low`s center, the general track is expected to move west to east
across the southern Bering Sea with its triple point hovering
along the Aleutian Chain through midweek. Temperatures for the
Aleutians are expected to be in the mid 40s to lower 50s.

&&

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

The global and regional models are in fair agreement through
Friday with the persistent upper level trough over mainland
Alaska and the Gulf becoming less defined into Friday as it
begins to interact and merge with an upstream shortwave in the
Bering Sea. The Canadian model suggests the upper level closed
low remains over Central Alaska. However, preferred GFS/ECMWF
solution that has the upper level low remaining over the South
Central Alaska and the northern portion of the Gulf of Alaska.

The surface low and attached fronts will quickly move over the
Central Aleutians and Alaskan Peninsula Thursday and then stall
out over Gulf of Alaska through Saturday. Scattered coastal
precipitation and gale force northerly gap winds are likely as
this impactful system crosses from the Bering Sea and into the
Northern Gulf Friday and Saturday.

High pressure will ridge into the Western Bering Sea ahead of
another North Pacific system that approaches the area early next
week.


-DD

&&

.AVIATION...

PANC...VFR conditions and light winds will persist. Additional
upper level short-waves moving in from the southeast today will
likely bring showers back to the terminal. While exact timing is
challenging, the best opportunity for showers will be between
18Z and 00Z today. Ceilings could briefly lower to around or just
below 5000 feet in steadier showers. Ceilings will lift
considerably tonight as upper flow backs around toward the north,
bringing an end to the steady stream of short-waves from the Gulf.


&&


$$