884
FXAK68 PAFC 291557
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
757 AM AKDT Wed May 29 2024

.Update...

Decreased likelihood of precipitation across the Anchorage Bowl
this morning. Current conditions and trends are diminishing and
plan on seeing isolated to scattered showers only through the
early afternoon. All other aspects of the forecast remain
unchanged.

-ss

&&

.PREV DISCUSSION... /issued 526 AM AKDT Wed May 29 2024/

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

An upper-level trough extending from the central interior south to
the Kenai Peninsula this morning will continue to track west
throughout the day. A second, weaker wave over the eastern Copper
River Basin will also move west this morning, catching up with
the initial trough and helping to enhance shower activity from
the Anchorage Bowl north and west to the Mat-Su Valleys, including
the Chugach and Talkeetna Mountains. The showers will begin to
diminish in coverage across valley locations from south to north
by this evening as the trough moves over the Alaska Range. Gap
winds will also be on the increase later today, peaking in
intensity later this afternoon, as the trough lifts north and
ridging builds along the coast ahead of a slow moving frontal
system over the Gulf.

The aforementioned surface front over the Gulf will weaken and
stall over the northern Gulf for Thursday. The southeasterly flow
ahead of the front, coupled with an upper-level shortwave ahead of
the surface feature, will keep conditions unsettled with clouds
and showers persisting along the coast through Thursday night.
Scattered showers are also possible across the higher elevations
of interior Southcentral Thursday afternoon and evening as the
upper-level wave continues to move north to the Alaska Range. An
isolated thunderstorm is also possible along the eastern foothills
of the Talkeetnas. Gusty southerly gap winds will again increase
Thursday afternoon and evening as the trough lifts north.

By Friday, as conditions become more tranquil across the interior,
light rain showers linger from Kodiak Island northeast to the
southern Kenai Peninsula. A deepening surface low tracks into the
southern Gulf with easterly gales and widespread rain. Its
frontal system lifts north and west through the day, with winds
and rain spreading into in the northwest Gulf late Friday.

-TM

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

A weakening low centered north of Unalaska this morning extends a
front along the Southwest Alaska coast. Associated with this front
is light precipitation falling over the Western Capes and northern
Bristol Bay and gusty southeasterly winds across the northern
Alaska Peninsula and interior Bristol Bay zone. This front will
slowly lift northward through the day, bringing rain onto the
northern Bristol Bay coast, including Dillingham, and a chance of
rain (though it is mostly expected to be dry as a result of
downsloping) to areas closer to the Alaska Range, such as King
Salmon. The arrival of the front, bringing increased cloud cover
and a slightly cooler air mass, is expected to keep temperatures
closer to (or even slightly below) normal today. It will also
promote some instability for rain shower development along the
Kuskokwim Delta coast. Further inland, conditions are expected to
be mostly dry, with the exception of the Lower Kuskokwim Valley
near the Alaska Range, which is likely to see rain showers
enhanced by two separate upper-level shortwaves tracking into the
area from Southcentral Alaska this morning and later this evening.
The eastern Aleutians and Alaska Peninsula can expect periods of
rain showers today closer to the low center.

The front weakens heading into Thursday, but the remnant moisture
pervades much of Southwest Alaska, leading to conditions
conducive for scattered showers across much of the lower
elevations Thursday afternoon/evening. While the low in the
eastern Bering Sea dissipates, weak shortwave troughs continue to
lift across Southwest Alaska into the weekend, with conditions in
the lower-levels of the atmosphere remaining fairly static. This
will allow for continued periods of light rain showers
developing each afternoon through at least Saturday.

Out west, a strong Kamchatka low pushes a gale-force front into
the western Bering/Aleutians Wednesday night. This leads to a
period of light to moderate rain pushing through the western
Aleutians. The front reaches the central Aleutians on Thursday,
having weakened below gale force along much of its length. By
Thursday night, the front moves into the eastern Aleutians as the
low tracks into the western Bering. South of the low center, winds
gust out of the west to gale force, with rain showers wrapping
around the low bringing a second round of precipitation to the
Aleutian Chain. The low continues east, tracking just north of the
Aleutians through Saturday as it weakens. Its front approaches the
Southwest coast, but there is good model agreement that it remains
offshore before dissipating this weekend, only barely brushing
the coast.

- Quesada

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

An elongated area of upper level troughing continues across the
Bering into the Gulf of Alaska. The Gulf low weakens and becomes
absorbed by a second center moving across the Southern Bering and
Alaska Peninsula by Sunday. The jet stream energy maintains its
track to the South of the Aleutians through the beginning of the
week. A deterministic model blend hold good confidence through the
weekend before an ensemble blend takes over. Weak ridging sets up
over the Central and Northern Mainland, as well as over Siberia,
which will allow for lower level thermal troughs to form across
the Central Interior beginning in the new week.

Sustained Easterly to Southeasterly airflow over the Southcentral
areas spreads increased moisture as far North as the Alaska
Range, and brings showers with each Easterly wave. Potentially
larger amounts of rain over the Copper River Basin associated with
more convective events are expected. Transient lows, fronts and
troughs spread their precipitation over the Aleutians and Bering,
and into Southwest Alaska, and the AKPEN and Kodiak Island.

-Kutz

AVIATION...

PANC...VFR conditions to persist through the forecast period.
Lingering gusty southerly winds early this morning out of
Turnagain Arm will diminish slightly by mid-morning, becoming
light but remaining south to southeasterly. Gusty southerly winds
up to 30 mph to kick back up by this afternoon and are expected
to persist through the evening hours tonight, coming to an end
again by early Thursday morning. Occasional MVFR conditions are
possible with any shower activity this morning.


&&

$$