Gale Warning 319, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
433 AM AKDT Sat Apr 27 2019

.ANALYSIS AND UPPER LEVELS...

Weak offshore flow and clear skies persist over most of
Southcentral and Southwest Alaska as upper ridging extends from
the Gulf of Alaska to the Arctic. An embedded mesoscale low is
centered over the Kenai Peninsula. Radar has picked up on virga,
and some high clouds rotating around the low towards Prince
William Sound can be observed on satellite. However, low and mid
levels are too dry for precipitation. Warm, moist air continues to
flow towards the AKPEN, ahead of a North Pacific low, bringing
clouds and light precipitation to the AKPEN and eastern Aleutians.
Farther west, a gale force low is approaching the western
Aleutians.

&&

.MODEL DISCUSSION...

Models remain in general good agreement for the short term. There
is uncertainty with the set up of a low in Southcentral late
Sunday into Monday. A farther west track as depicted in the EC,
would indicate higher precipitation chances for the Gulf coast.
The GFS solution on the other hand would keep most precipitation
offshore. A blend was used for precipitation fields for this
forecast package.

&&

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

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2/Today
through Sunday night)...

High pressure and a dry air mass will lead to continued warm and
sunny conditions across Southcentral through the weekend. Pressure
gradients and winds have slackened since yesterday. This will
allow sea breezes to form along the coast during the afternoon and
evening, serving to keep high temperatures a bit cooler than on
Friday. For inland areas expect similar or slightly higher high
temperatures.

Meanwhile, a warm front over the North Pacific will approach
Kodiak Island, with rain spreading northward across the island
this afternoon through tonight. Rain will continue through at
least Sunday night as the front makes slow northward progress
across the Gulf. With easterly low level flow, the east side of
Kodiak Island will see the most rain, while the southwest portion
of the island will see little or no rain.

&&

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

High pressure will slowly retreat from Southwest Alaska by Sunday
and Monday as a dying front gets hung up along the coast. The
primary effects from this will be gradually increasing clouds,
breezy, southeasterly winds, and warming temperatures. The main
impact will be another couple days where lots of sunshine results
in lower relative humidity levels. On Sunday, the higher winds
could result in increased fire weather concerns. On Monday, there
is considerable uncertainty as to the strength of an upper level
low that will drift westward somewhere over the area. The track
and strength of the upper level low will have a large impact on
where and when any rain develops over Bristol Bay. Either way,
Monday will be the cloudiest of the next three days, but with
warmer air moving it, may not necessarily be the coldest.
Southeasterly winds will remain breezy through the day.

&&

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

The pattern through Monday across the Bering will generally be the
storm track and unsettled weather across the western Bering, with
ridging and generally quieter weather across the eastern Bering. A
pair of lows will track north across the western Bering. The first
and weaker of the two lows is moving into the western Aleutians
this morning. It is forecast to produce gale force winds to the
north and east of the center. As it moves towards Kamchatka on
Sunday it will quickly weaken. The second stronger low will be
quick on its heels, moving into the western Aleutians by midday
Sunday. This second low will become vertically stacked and stall
out over the far western Bering by Monday afternoon, with its
leading front stalling out to the west of the Pribilofs and
between Atka and Dutch Harbor by Monday afternoon. This low will
also produce gale force southerly winds ahead of the center in
many of the same locations as the first low. Elsewhere, moisture
associated with a weak, disorganized disturbance will continue to produce
rain along the Pacific side of the Alaska Peninsula through
Sunday.

&&

.MARINE (Days 3 through 5)...
Monday through Wednesday look to see light winds for the Gulf
with the highest speeds no greater than 30 kt. Out west, gale
force winds are expected for the Bering that will be the strongest
on Monday and taper off through Wednesday. However, there is
uncertainty concerning the location of the gales. Most guidance
agrees on the central Bering but there is a chance the strongest
core of winds could be farther east.

&&

.LONG TERM FORECAST (Days 4 through 7)...
Beginning late Monday there is increased confidence of a low over
the western Bering and ridging over mainland Alaska. This setup
would keep warm air over the mainland and an active storm track
through the eastern Bering and west coast with multiple lows
moving through the pattern. By wednesday the models are struggling
to lock on to the main features resulting in lowered confidence
with the positioning of any lows moving through the area. However,
there is generally good agreement that any systems moving through
would be weak. With the lower confidence in the operational
models, the ensembles were preferred late in the week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gales: 177 178 411 412 413.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MM
SOUTHCENTRAL ALASKA...SB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JW
MARINE/LONG TERM...DK