041
FXAK68 PAFC 290012
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
412 PM AKDT Sun Apr 28 2024

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

An upper level ridge continues to promote sunny skies and a lack
of active weather for Southcentral. The strength of this ridge has
grown since yesterday, clearing out Kodiak Island as well. The
warmest temperatures so far this season are expected across
Southcentral today due to the clear skies, limited residual
snowpack in the lower elevations, and modest low-level thermal
ridging in place. While the ridge is still building this weekend,
cooler air remains aloft, and along with the clear skies, ample
surface heating would be conducive to localized convective showers
around Southcentral. However, given the strength of the ridge,
any showers produced this way would likely be isolated and short-
lived. Additionally, given the surface heating, a return of the
summer seabreeze is expected this weekend, predominantly Sunday,
in marine communities such as Seward, Valdez, and Whittier.

At time of writing, the Copper River Basin is seeing some showers
pop up along the northern edge of the area, as well as on the far
Eastern side of the Wrangell Mountains. Models have been over-
estimating the breadth of these showers, advertising higher
activity over much of the areas of elevation. In reality, much of
the surface heating in these areas needed for convective activity
is instead put into heating/melting the still decaying snowpack.
Therefore, isolated showers are expected to pop up along portions
of the Copper River Basin and along the mountain-side slopes,
however are not expected to be widespread nor long-lasting
systems. By Monday, will also see a general increase in
cloudiness across Southcentral as the weak upper level ridge
begins to breaks down. Southerly flow up Cook Inlet will work to
keep us slightly cooler than currently, and steadily fill the
skies.

-CL

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Wednesday morning)...

Ridging centered over Southwest this evening will breakdown and
push east as an upper level low currently over the Pribilofs
slides south over the Alaska Peninsula through tomorrow afternoon.
This will induce more cloudcover and onshore flow along the
coast, leading to cooler temperatures for much of the region.
Interior areas will remain warmer, but will still have a general
cool down as cloudcover increases. For Tuesday and Wednesday,
week upper level shortwaves will pivot north around the trough,
generating some isolated to scattered showers near the foothills
where snowpack no longer exists. Otherwise, temperatures near
average are expected with increasing cloudcover through Wednesday.

Over the Bering, a developing low in the north Pacific will move
north near Shemya by Monday afternoon, sending a gale force front
into the western Aleutians and Adak. The main forecast change is
that this front is slower to move east and the low stalls out
longer near Shemya due to stronger ridging over the central
Bering. As the front slides east around the base of the trough,
an elongated low will develop along the triple point reaching the
eastern Aleutians on Tuesday and the Alaska Peninsula Wednesday.
Winds will be marginal by this time.

&&


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

Low pressure moves into the western Bering Sea on Thursday, its
front extends over the Aleutians by Wednesday. Multiple low
centers track through the Gulf of Alaska through late week and the
weekend. High pressure may linger across inland portions of
Southcentral Alaska through the end of this week before the
pattern shifts this weekend with a front moving onshore. Areas
along the north Gulf coast, Prince William Sound and Kodiak Island
will likely see periods of rain, however, there is still some
uncertainty how far inland the precipitation will track.

&&

.AVIATION...

PANC...VFR conditions will persist. A weak Turnagain Arm jet will
develop this evening into the overnight hours as surface ridging
sets up along the north Gulf coast. The strongest winds should
remain south of the terminal, with only a light (less than 10 kt)
south to southeast wind moving into the terminal around or shortly
after 06Z.

&&


$$