468
FXAK68 PAFC 261325
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
525 AM AKDT Wed Jun 26 2024

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

Discussion:

Water vapor imagery and H5 heights show a large occluded low moving
into the central Bering this morning with frontal boundary lifting
north across the southern AKPen and western Gulf. The upper ridge
that has been entrenched over much of Alaska this past week has
shifted slightly to the northeast with ridge axis now positioned
from east-central Alaska down into the southern Yukon. Enhanced
southerly flow between the ridge and Bering low has allowed for
increased low-level moisture (in the form of low stratus and patchy
fog) to advect up the Cook Inlet and is beginning to work up into
the Susitna Valley this morning. Low stratus and patchy fog have
also been noted on nighttime microphysics RGB satellite imagery
working northward through the valleys of the Kenai as well as
valleys across the southern Copper River Basin. Expect some of this
stratus to start mixing out by mid to late morning, but with surface
ridging still in place over the Gulf, Kenai Peninsula, and Prince
William Sound, it may linger into the afternoon for some areas.
Coastal areas along the Gulf will likely see little change from the
past several days.

With the upper ridge shifting eastwards, thunderstorms chances will
also shift slightly to the east. Isolated to scattered thunderstorms
are once again possible along the slopes of the Talkeetna Mountains,
the Alaska Range, and the Wrangells; as well as across much of the
Copper River Basin. Instability will increase through the day today
as temperatures warm back into the 70s for the Mat-Su Valley and
Copper River Basin. CAPE values of between 500 to 1000 J/kg look to
set up from the Talkeetna Mountains over to the Wrangells on the
southern side of the Alaska Range. While most of the convection will
be more pulse-type, diurnally driven...a weak wave rounding the
upper low combined with another weak easterly traversing wave
rounding the ridge may allow enough forcing to get more scattered
thunderstorms going over the Talkeetnas. As diurnal heating
decreases this evening, thunderstorms will quickly start to
dissipate. Thursday will again see the potential for isolated to
scattered storms, but again shifts eastwards into the Copper River
Basin.

- PP

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA/ALEUTIANS
(Days 1 through 3: Today through Friday evening)...

Weak disturbances will continue to tracking across interior
Southwest Alaska through today. As a result, scattered wet
thunderstorms are possible this afternoon and evening across
eastern portions of the Middle Kuskokwim Valley and along the
Western Alaska Range. More stable air works inland for Thursday
and Friday which should cease thunderstorm chances for the
interior.

Towards the coast, there is a gale-force front that is draped in
the eastern Bering Sea along the mainland Southwest coast this
morning. Winds continue to be elevated along Kuskokwim Bay this
morning where southeast gusts around 50 mph are and will continue
to be common around Kipnuk, Kwigillingok, and Kongiganak. With
this good fetch of southeasterly flow into the coast, there is a
High Surf Advisory in effect the Kuskokwim Delta through early
Thursday morning. Water levels are expected to rise during high
tide to 3 to 6 feet above the normal highest tide. The peak of
water level rise is expected this afternoon. Meanwhile, the front
that is causing all the weather on the coast will not make it far
inland before weakening completely this evening and overnight.
Therefore, the lion`s share of precipitation will remain on the
coast with little progression inland. The low`s trailing front
then comes to coastal Southwest Thursday morning with more rain
and wind expected. Winds will not be as strong with this second
round though. The low will eventually make a turn back to the
northwest Thursday evening toward the northwest Bering Sea by
Friday. However, subsequent waves will continue to lift into the
coast from the Bering through Friday. Thus, generally expect the
coast to remain unsettled the next few days with drier conditions
inland.

Out west, the same system that is battering the coast with rain
and winds is doing the same along the Aleutian Chain and the
Pribilof Islands. Expect continued rainy and gusty conditions
through Thursday evening. This is especially true for the central
Aleutians. As conditions ease Thursday evening, there is no rest
for the weary as another North Pacific low lifts toward the
western Aleutians during that time. This low will straddle the
Chain and make it to the eastern Aleutians southern Alaska
Peninsula Friday evening with another round of wind and rain in
store.

&&

.LONG TERM FORECAST (Days 4 through 7)...

A ridge will remain over the area for the weekend for
Southcentral and Copper River Basin. An isolated rain shower or
thunderstorm is possible though into the beginning of next week.
In the Southwest, a series of lows progress through the Bering Sea
into the Interior Southwest bringing cooler temperatures, clouds
and frequent rain showers to the area through the early next week.

-DJ

&&
.AVIATION...

PANC...VFR conditions will persist through the TAF period, with
calm southwesterly up-inlet flow prevailing into Friday. Building
high pressure over the area will also result in decreased
precipitation chances over the terminal. Fog and low stratus has
spread up Cook Inlet, but has stopped just shy of reaching the
terminal. If it makes it into the terminal could see ceilings
drop down to, or below, IFR until it is able to mix out later this
morning.

&&


$$