Gale Warning 400, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
414 PM AKDT Thu Jun 8 2023

.ANALYSIS AND UPPER LEVELS...

A broad upper level low continues to rotate in place and weaken
over the Bering. This has been driving much of the unsettled
weather over the southern half of the state as several upper level
waves rotating around the low fuel persistent clouds and showers.
Radar imagery confirms widespread rain over the northern Gulf
coast, including Prince William Sound. Additionally, rain showers
are gradually filling in over the Alaska Peninsula and Bristol
Bay area.

&&

.MODEL DISCUSSION...

Model solutions are in generally good agreement through Friday
night. By Saturday, models are all suggesting a North Pacific low
lifting over the Alaska Peninsula/Kodiak Island area, however
there is a lot of disagreement regarding the low center position,
particularly on Saturday night. Currently the NAM solution is
weaker, and brings the low farther east while the GFS is the
strongest and farthest west solution. The EC is splitting the
difference between the two. This has led to lower confidence in
the forecast for the weekend, as the position of the low center
will impact the location of strongest winds, particularly over the
Gulf.

&&

.AVIATION...
PANC...VFR conditions with periods of light rain will persist.
With continued cloudy skies across the region, it is a marginal
situation for Turnagain winds to bend into the terminal. Weak
pressure rises along with a little bit of warming inland should be
enough to bring some gusty south to southeast winds in during the
evening hours. Friday afternoon/evening looks like a much better
set-up, with a short-wave moving into the southern Gulf and stronger
coastal ridge out ahead of it, so gusty winds will move in much
earlier.

&&

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

A persistent cool, cloudy, southeasterly flow pattern is set to
continue through the weekend for Southcentral Alaska. A weak front
remains hung up along the north Gulf coast and is set to slowly
track inland overnight. Weak shortwaves tracking north from the
Gulf along this front will enhance periods of light rain showers
for inland locations. Pressure rises behind a weak low crossing
the Aleutian Range into Southwest Alaska will help to increase the
typical southeasterly gap winds through Turnagain Arm, Knik River
Valley, and the Copper River Basin this evening.

Attempting to lock onto some of the weak shortwaves tracking
north, the first over the Gulf this afternoon will track over the
Copper River Basin this evening, with limited inland impact.
Coastal precipitation will diminish as this lifts the front
northward. Then, a second shortwave trough tracking up from the
western Gulf enhances precipitation along the southern Kenai
Peninsula Friday afternoon. This shortwave will be associated with
weaker cross-barrier flow compared to this morning's feature,
which may allow for more (light) precipitation to spread inland
over the western Kenai Peninsula and north into Anchorage and the
southern Susitna Valley by Friday night. Steady rain increases
along the north Gulf coast as well as the shortwave tracks north
on Friday night.

For Saturday, this shortwave will be of particular interest as it
looks to aid with increased instability over inland Southcentral.
It will be accompanied by cold air aloft which will, despite
generally cooling temperatures, increase mid-level lapse rates and
enhance the upper-level dynamic support. This will combine with
breaks of sun to trigger rain showers over inland locations, with
a chance for some of these showers to become thunderstorms in the
Susitna Valley and Copper River Basin.

This will be the only taste of summer through the short term as an
unseasonably strong low tracks into the Gulf on Saturday. Kodiak
Island will begin to see heavier rain Saturday evening, before
widespread gales and rain push to the north Gulf coast Sunday
morning.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days
1 through 3: Tonight through Sunday)...

The stubborn Bering low will continue to spin near the Central
Aleutians through Saturday, sending various embedded shortwaves
across most of the region and maintaining generally showery and
breezy conditions. There is increasing confidence for isolated
thunderstorms across the eastern Lower Kuskokwim Valley for
Saturday afternoon. Also on Saturday afternoon, a compact low
approaches the Alaska Peninsula from the North Pacific. Although
there are some model differences in the low track, this feature is
expected to bring steady rain and elevated winds mainly to
Southwest and the Eastern Bering through Sunday. Expect isolated
rain showers and lighter winds across the Bering and Aleutians
through the weekend.

&&

.LONG TERM FORECAST (Days 4 through 7/Monday through
Thursday)...

A persistent upper level low over the Bering is still the key
feature for the start of next week. This will keep widespread
cloud cover in place over the Bering with associated shortwaves
rotating around the low generating showers. By late Tuesday,
models hint at a weak ridge over the Gulf of Alaska, which may
bring a brief reprieve to Southcentral by midweek, however it's
not looking likely that this ridge will be strong enough to disrupt
the pattern. By the end of the workweek, models suggest another
North Pacific low lifting over the Alaska Peninsula and
introducing the possibility for continued clouds, rain, and gusty
winds.

&&

SYNOPSIS AND MODEL DISCUSSION...KO
SOUTHCENTRAL ALASKA...CQ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AF
LONG TERM...KO