Small Craft Advisory 438, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
312 PM AKDT Tue May 26 2020

.ANALYSIS AND UPPER LEVELS...
The upper low over Saint Lawrence Island continues to track
north. Its associated short wave is moving slowly north across
Southwest Alaska. A weakening Easterly Wave which moved through
Southcentral overnight is weakening as it moves through the
western interior. Much of Southwest Alaska is under mostly cloudy
skies. Showers associated with a northward advancing wave are
moving north across the area. It is also getting rather convective
with some some breaks over the lower Kuskokwim Valley. The Bering
Sea and Aleutians are generally under mostly cloudy skies with
areas of rain and showers. A northward advancing upper wave
accompanied by some sunshine inland is starting to Kick off
showers across Southcentral Alaska. Temperatures which started in
the 30s across the Copper River Basin have started to rebound with
sunshine and cloud breaks. except for gusty southeast winds along
the Delta Coast, and sea breezes along Cook Inlet, winds are on
the light side.

&&

.MODEL DISCUSSION...
Models overall in in generally good agreement with synoptic
features through the short term. Local effect gap winds across
Southcentral will likely be handled best by higher resolution
models and hand edits.

&&

.AVIATION...
PANC...VFR and generally light winds will persist. Showers
developing this afternoon are expected to stay mainly to the east
of the airport complex. Occasional gusty southerly winds late
this afternoon into early evening are possible.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
An upper level trough is slowly moving through Southcentral
Alaska from south-to-north this evening and overnight. The colder
air aloft and some surface heating due to enough breaks in cloud
cover is creating an unstable enough environment for numerous
showers this evening. These showers should greatly diminish by
late in the evening as the surface heating diminishes.

Wednesday will see the beginning of a warming and drying trend for
the next few days. Some gusty northerly winds are likely to
develop through channeled terrain in the Alaska Range Wednesday
night and then models indicate they should diminish some during
the day Thursday. There is some uncertainty as to how much they
will diminish Thursday as they have a habit of persisting once
they get going. This is the biggest area of concern in the current
forecast.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...
Scattered showers and possible isolated thunderstorms will end
this evening as a low departs to the north. Skies will remain
mostly cloudy Wednesday, especially near the coast. While
scattered showers may redevelop near the mountains Wednesday
afternoon/evening, the lack of instability due to the cloud cover
should sufficiently inhibit any thunderstorms. An upper ridge will
begin to have more of an influence over the area by Thursday,
bringing partly cloudy skies and warmer temperatures through the
end of the week.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...
A series of fronts will track across the western Aleutians
through Friday bringing moderate rain and gusty southerly winds.
An upper ridge will prevent these fronts from moving farther east.
Thus, conditions east of and including Unalaska and the Pribilofs
will remain generally benign through the end of the week.

&&

.MARINE (Days 3-5: Friday through Sunday)...
Gulf of Alaska: No significant winds or seas are expected. A weak
low skirting the Gulf Friday however could briefly produce high
end easterly small craft winds over the southern Gulf through
Friday evening.

Bering Sea/Aleutians: A weather front will bring sub-gale
southerly winds to the eastern Bering Sea/east Aleutians Friday.
Winds will then diminish through Sunday.

&&

.LONG TERM FORECAST (Days 4-7: Saturday through Tuesday)...
The upper level Rex block over the mainland and the Gulf starts
to break down Saturday as the upper ridge retreats north and
splits. This allows the Upper low over the Gulf to track slowly
north through early next weak. The increased easterly flow aloft
will drive easterly waves west across Southcentral. This will
result in cloudy conditions, increased chances of rain/showers,
and cooler temperatures across much of Southcentral into early
next week.

For Southwest Alaska, an upper level trough will setup over the
southern mainland this weekend. This will generally bring
increasing clouds and chances of showers. Any stronger upper
waves could set off isolated thunderstorms in the afternoons,
depending on how much instability and sunshine can develop earlier
in the day.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning 177 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...RC
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AP
MARINE/LONG TERM...RC