Small Craft Advisory 238, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
439 PM AKDT Wed Mar 11 2020

.ANALYSIS AND UPPER LEVELS...
There is an upper level ridge over the central and eastern Bering
Sea. There is an upper level trough over northwest Canada, with
northwesterly flow aloft over most of mainland Alaska. A surface
high is centered over the far eastern Bering and Southwest
Alaska. Low level offshore flow is over most of southern Alaska
into the Gulf. A strong front associated with a low just to the
west of the Kamchatka Peninsula is over the far western Bering
just west of the western Aleutians. Conditions are dry over almost
all of southern Alaska and the Aleutians with almost no
precipitation.

&&

.MODEL DISCUSSION...
The numerical models continue to be in very good agreement. The
high resolution models are preferred due to the better handling of
gap winds. Forecast confidence is above normal.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Dry and cold persists through the end of the work week. Gusty
offshore flow through gap terrain increases overnight as an upper
level disturbance dives toward the northern Gulf from the
interior. Gusts should peak during the morning hours on Thursday,
then taper down during the afternoon. Marine areas near the coasts
are expected to experience heavy freezing spray with gusty winds
tonight through Thursday. Clear and calmer conditions are
expected to set up across the southern mainland on Friday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...
Dry and cold weather will continue for Southwest Alaska through
tomorrow morning before an upper level ridge begins to build into
the area during the day Thursday. This will lead to a moderation
in temperatures through Saturday with each day warmer than the
previous.

Upper level energy associated with a low pressure over the North
Pacific will be drawn northward on the west side of the upper
level ridge Thursday afternoon into Thursday night. As this
continues north, precipitation chances will increase for the
Kuskokwim Delta Coast beginning Friday afternoon through the
weekend.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
An upper level ridge currently across the western Bering will
continue moving eastward into the central and eastern Bering
tonight into Thursday keeping the weather across the area quiet.

A storm force low will move northward through the North Pacific
and into Russia overnight into Thursday. The front associated
with this low will move into the western Aleutians and western
Bering tonight bringing rain to Shemya and Attu Island. As this
front continues to move across the Aleutian Chain, it will
gradually slow down and even stall over the islands west of
Amchitka.

A low spinning over the North Pacific about 800 nm south of Dutch
Harbor will have some of the energy associated with it drawn
northward towards the central Aleutians and central to eastern
Bering Sea Thursday afternoon into Thursday night. A warm
southerly flow will bring in milder air on the backside of the
upper level ridge bringing mostly rain and widespread
precipitation to the region. This will cause the aforementioned
front moving east across the western Bering and western Aleutians
to slow down and stall. As it stalls the front will be stretched
and sheared apart as some weak upper level ridging tries to build
into the western Aleutians Saturday.

&&

.MARINE (Days 3 through 5)...

A storm force system over the northern Bering will keep an area
of storm force to high end gale force winds west of St Matthew
Island and north of 56N on Thursday. By Friday, this system will
have weakened, but enhanced winds and rough seas are still
anticipated into Saturday. Shifting to the North Pacific, a low
will approach the central and eastern Aleutians Thursday night,
bringing the next round of precipitation to the eastern Aleutians,
including Dutch Harbor, through Friday night. A ridge will set up
over the Gulf Of Alaska and mainland. Once this ridge gets
established, the active corridor for low tracks will be the NW
Pacific to the Western Bering.

&&

.LONG TERM FORECAST (Days 3 through 7)...

The global models continue to bring a high amplitude ridge into
the Gulf of Alaska and Southcentral. This will keep clear skies
and dry weather over most of Southcentral Alaska. However, the
weather will be active over the western/central Aleutians and
western/central Bering. With the block in place over
Southcentral, the lows will follow the path of least resistance.
The ridge remains steadfast through Tuesday.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...High wind warning 131.
MARINE...Storm 411 412. Gales 130-132 138 150 155 172 178 413.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...BL
SOUTHCENTRAL ALASKA...KH
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...SA/MV
MARINE/LONG TERM...PS