Sterling, Alaska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

919
FXAK68 PAFC 061535
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
635 AM AKST Mon Jan 6 2025

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

Discussion:

The forecast remains pretty much on track this morning with high
wind or winter weather headlines out for much of Southcentral
through Tuesday. The first of several systems this week have
moved through as of this morning. The latest of these quickly
lifted north across the western Gulf towards Kodiak overnight and
has now moved up into the northern Susitna Valley. This system
resulted in some gusty winds for the Cook Inlet, Kenai, and Homer.
Steady precipitation has been falling for most of the coastal
areas along the Gulf. Most of this has been falling as rain for
lower elevations, but for areas where the cold air has been more
difficult to scour out such as Valdez, precipitation has remained
all snow. However, temperatures has inched up to 32 degrees in
Valdez and expect a change-over to a wintry mix then possibly to
all rain at some point today.

We now turn our attention to a very strong system that is currently
lifting northwards out of the North Pacific. Strong lift associated
with this system is already resulting in the next round of moderate
to heavy precipitation to blossom over the northern Gulf. But that
isn`t the only thing this system will bring. As this system
approaches, it will bottom out around 960 mb just southeast of
Kodiak Island. The surface low is then progged to move up the Cook
Inlet and elongate, but still remaining quite strong at 967 mb.
Winds will start to to increase over much of Gulf with both the NAM
and GFS developing a swath of hurricane force winds from the SW
entrance of Prince William Sound to the Copper River Delta and
extending further back to the southeast. These winds will funnel
towards the western Sound by this evening. Cordova will see winds
starting to increase this morning with strongest winds of 40 to 55
mph with gusts up to 75 mph are expected during the afternoon and
evening hours before decreasing overnight. As such, a High Wind
Warning has been issued for Southeast Prince William Sound. Strong
winds will then work into Whittier later this afternoon and evening
with gusts up to 65 mph possible.

Strong winds will also work over the Kenai and Chugach Mountains
with very strong winds for higher elevations. Winds will funnel down
into Portage and the Turnagain Arm by this evening with gusts up to
75 mph along the Arm and higher gusts possible for Portage. A High
Wind Warning is also in effect for these areas. Lastly, winds are
expected to increase through the Mat Valley this afternoon as the
pressure gradient tightens. As the low lifts north out of the Inlet,
Mat winds will look to slacken as the Knik winds take over. As such,
a High Wind Warning is also in effect for the Mat Valley.

Lastly, this system will bring a mix of precipitation with it.
Precipitation will increase in coverage by this afternoon with
precipitation working up the inlet. The southern end of the Kenai
Peninsula will see rain working in this morning with temperatures
having warmed into the 40s. Further north temperatures are still in
the 30s and upper 20s resulting in  wintry mix. Precipitation will
continue to work up towards the Anchorage Bowl and Susitna Valley
this afternoon. Precipitation and strong winds will wind down
Tuesday as the system exits the region; however, another system
looks to follow a similar track by midweek though there are still a
lot of details to work out on that system.

- PP

&&


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

A cold airmass remains over the central and western Bering while
unsettled weather brings precipitation to Southwest Monday and
Tuesday.

This morning, a small occluded low will remain over Unalaska
through the afternoon with continued light rain for the eastern
Aleutians and AKPen. A second low over Cook Inlet weakens as it
encounters the Alaska Range, but retains enough energy to bring
periodic snow across Southwest Alaska through the morning.
Meanwhile a larger North Pacific low races up the western Gulf
through the day before pushing its front over Southwest Monday
afternoon. This system is expected to bring additional widespread
snow showers for most of interior Bristol Bay and the Lower
Kuskokwim Valley, with a focus on an area including Dillingham,
New Stuyahok, and Koliganek, which may see anywhere from 3 to 8
inches of snow and reduced visibility through Tuesday morning.

Warmer surface temperatures will generally reduce snow
accumulation south of King Salmon along the AKPen, however, Togiak
may see up to two inches of snow through late Monday night.

Finally, the cold airmass over the western and northern Bering
will continue to bring gusty northeasterly winds from Saint
Lawrence Island down the western half of the Bering. Gusts of 35
to 50 knots will be possible within this region with seas of 15
to 20 feet. Further east, the threat of freezing spray continues
for the Bering Sea north and west of the Pribilof Islands. Heavy
freezing spray will continue along the ice edge between Nunivak
Island and north to Saint Lawrence Island.


&&


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

A very active weather pattern will continue for much of southern
Alaska through the end of the week and into next weekend. The
longwave pattern features a strong upper level low dominating much
of the Bering Sea-western mainland Alaska and a steep ridge of high
pressure along the Canadian Coast and Eastern Alaska. The high
pressure ridge will weaken and retreat eastward slightly along the
Gulf of Alaska and Southern Alaska allowing a very strong North
Pacific low and its associated fronts to travel northward into the
Gulf and into the Alaskan Peninsula Thursday and into Friday before
being absorbed by the long wave trough of low pressure over the
Baring Sea. This pattern will bring unseasonable warmer temperatures
and mixed precipitation along the coastlines near the surface and
has the real potential for heavy snow accumulations in the higher
elevations.

The upper level low will gradually retreat back into Eastern Siberia
and the Chukchi Sea as the Ridge of high pressure reasserts its
dominance Friday and into Saturday. This will flatten out the
southern portion of the long wave trough allowing several compact
surface lows and their associated fronts to transit along the
Aleutians and coastal southern Alaska.

Confidence in the model guidance is moderate with a slight bias
between the GFS and European solutions through Thursday. The
European and Canadian better handle the synoptic features Friday and
into Saturday.

&&

.AVIATION...

PANC...Mainly VFR conditions are expected to persist through most
of the TAF period. Strong downslope southeasterly flow through
today will begin to turn more southerly tonight. This will allow
precipitation to fill in over the area with better chances of MVFR
conditions tonight into Tuesday morning. VFR conditions should
return by mid-morning Tuesday as precipitation becomes more
scattered in nature.

Meanwhile, there is a brief period for Turnagain Arm winds to
bend into the terminal this morning before down-inlet flow
strengthens again late morning and northerly winds resume late
morning to early afternoon through tonight. Winds aloft will stay
strong and out of the southeast which will promote low-level
windshear with winds at the surface remaining out of the north. As
flow throughout the atmosphere begins to turn more southerly
starting this afternoon, low-level windshear will diminish. Strong
gusty southeasterly winds return late tonight into early Tuesday
morning as low pressure moves up Cook Inlet and reorients the
pressure gradient to more of an east-west gradient.

&&


$$