Small Craft Advisory 620, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
439 AM AKDT Sat Jul 19 2025

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

A rather stagnant pattern is beginning to take shape across the
southern Mainland this morning as a Pacific ridge now begins to
build into the Gulf of Alaska, as evidenced by upper level clouds
moving with an anticyclonically curved jet stretching from the
Aleutians to Southeast. To the north, very weak flow is now in
place across Southcentral, with calm winds and widely scattered
mid level clouds in place near the remnants of a dissipating
shortwave trough moving overhead.

The prevailing theme for the next few days continues to be a
general warming trend through Monday as the Pacific ridge steadily
builds into place from the south. However, despite the high
pressure developing aloft, only intermittent sunshine it
anticipated given a few factors. For one, the ridge axis is likely
to set up towards the Copper Basin and AlCan border, leaving much
of the rest of the region under the influence of southwesterly
flow on the upstream side of the longwave ridge. In addition,
multiple shortwave impulses are expected to move out of the base
of a large Bering low out west and ride over the top of the ridge,
bringing increased lift and periods of denser mid level cloud
cover moving across from west to east through the weekend into
early next week. There remains potential for light rain to reach
into the Cook Inlet up into the Mat-Su Valleys with the approach
of each disturbance, though the model handling of precipitation
potential continues to be rather poor. While far from a guarantee,
the best chance for measurable rainfall to reach up into western
half of Southcentral still looks to be Sunday into Sunday night as
a somewhat more defined trough and moisture plume cross over the
Alaska Peninsula and move up into the region.

Otherwise, apart from the lingering light rain chances, expect
continued mild high temperatures in the 60s and 70s across lower
elevations until the high pressure ridge finally begins to break
down later in the week.

-AS

&&

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

The overall synoptic surface and upper level flow pattern
continues to be comprised of a vertically stacked high pressure
system in the North Pacific and a vertically stacked low in the
Bering, which together is reinforcing a southwest flow across the
region. Satellite imagery this morning reveals a large low
pressure system across the Western Bering Sea that continues to
remain quasi-stationary. This feature has promoted low stratus
along with showery and foggy conditions across the Bering,
including the Pribilofs. Its front continues to move eastward with
precipitation overspreading Kuskokwim/Bristol Bay coastal areas
and points farther inland over interior Southwest AK. Meanwhile, a
wave of low pressure has formed south of the Central Aleutians as
it has aligned itself with a shortwave trough.

Models are really honing in on pressure gradient induced small
craft winds as the occluded Bering low continues to remain quasi-
stationary and the ridge of high pressure over the North Pacific
starts to nudge northward. This swath of wind begins just to the
west of the Pribilof Islands, expands in coverage, and gradually
moves northeastward starting Sunday afternoon. Also around this
time, the wave of low pressure begins to quickly move across the
Eastern Aleutians and into the AK Pen, giving these locations a
quick round of rainfall. Guidance shows that this system quickly
falls apart as it continues to skirt along the AK Pen late Sunday
into the early morning hours of Monday.

The Bering low finally gains momentum late Sunday as the North
Pacific high pressure system continues to push northward. Guidance
suggests another wave of low pressure forms late Sunday and
follows a similar track as the first wave. A pattern change looks
to start near the end of the short term or just thereafter as more
ridging builds across the Aleutians and Bering from the south.

-AM

&&

.LONG TERM FORECAST (Days 4 through 7: Tuesday through
Friday)...

By Tuesday, southern Alaska will be devoid of a significant low
pressure system, with the pattern largely driven by a strong ridge
of high pressure built over the northern Pacific. This pattern
may still work to keep showers across Southwest and Southcentral
Alaska with plenty of cloud cover as air continues to flow in from
the Bering Sea. Shortwaves coming up and over the ridge will
maintain the unsettled pattern along the Alaska Peninsula and into
Southwest/Southcentral mainland Alaska. Expect more widespread
stratus built across the Bering Sea given the influence from the
ridge.

-CL

&&

.AVIATION...

PANC... VFR conditions will persist, with a westerly sea breeze
in the afternoons. A trough brings a slight chance of rain for
the terminal from late this afternoon and into the evening.
Ceilings are forecast to rise to 5000 ft around mid-morning, then
drop below 5000 ft in the late afternoon as the trough moves
through.

&&