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000
FXAK68 PAFC 180053
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
453 PM AKDT Fri Aug 17 2018

.ANALYSIS AND UPPER LEVELS...
A ridge building over the Gulf of Alaska and Southcentral is
bringing drying conditions with some breaks of sunshine across the
area. Meanwhile the eastern Aleutians and the AKPen are preparing
for a storm force low moving up from the North Pacific with rain
beginning to move into the area. The eastward progression of the
front is slowing as that low strengthens, and the Gulf ridge
builds ahead of it. Looking to the west, a gale force front is
starting to approach the western Aleutians.

&&

.MODEL DISCUSSION...
Models are in good agreement with the timing and placement of the
front associated with the North Pacific low that spreads across
the central Aleutians and AKPen starting this afternoon. Model
agreement has continued to improve over the past few runs.

&&

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

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Southcentral Alaska is in the break between systems, but in
August that does not necessarily mean that the weather will be
great. A short wave along the Alaska Range is keeping some showers
in that region. Those showers should slowly taper off as upper
level ridging moves in from the south. This ridging will bring
some partial clearing to parts of the area today, but the next
front is moving in from the Pacific and will bring more rain to
Kodiak Island beginning this evening.

The low associated with the front is moving slowly so its progression
was slowed up a little in the latest forecast. Gales will develop
in the marine areas along the Gulf side of the Kenai Peninsula as
well as around the Kodiak Island waters tonight into Saturday with
the tightening pressure gradient. While winds will also increase
through Turnagain Arm, they will mostly turn to the left and
down-Inlet Saturday and Sunday due to the low remaining well to
the southwest of Kodiak.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Tonight through Sunday)...
Fairly benign weather will remain over the area this evening
as a North Pacific low moves towards Bristol Bay for the weekend.
This low will bring strong winds to the Aleutian Range as well is
into Northern Bristol Bay into Sunday morning. As is normally the
case with strong easterly flow events, precipitation along the
lee of the Aleutian Range will be mostly limited from downsloping,
while areas west of King Salmon will see widespread rains. Rainfall
and gusty east winds will then spread northward into the Kuskokwim
Valley and Delta on Sunday as the low begins to weaken. This will
allow for continued cool and showery weather with diminishing
winds for most of the area to begin next week.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Tonight through
Sunday)...
The storm force low approaching the AKpen will spread strong
winds from the AKPen westward into the Eastern Aleutians. The
strongest of these winds will likely occur over the Dutch Harbor
area where gusts up to 60 mph are possible on Saturday. Along with
these strong winds, this low will bring rain to most of the
Aleutians and to the Bering Sea the east of the Pribilof Islands.
Areas further west on the other hand will remain fairly benign
into Saturday morning when another low skirting the Kamchatka
Coast will bring to spread rain and small craft winds to the
Western Aleutians that will persist for the remainder of the
weekend.

&&

.LONG TERM FORECAST (Days 3 through 7)...
The long term forecast beginning Tuesday features a high amplitude
ridge extending from the Western US coast north into the Yukon,
across far Eastern Alaska and up into the North Slope. A
negatively tilted upper level trough with associated surface low
will be swinging NE across the Gulf of Alaska and into
Southcentral, supported by a strong southerly jet stream. The
southerly jet will tap into a good moisture fetch bringing periods
of heavy rain to the Gulf Coast. The low weakens as it moves
ashore during the day on Tuesday though showers will linger across
most of the area through Wednesday morning.

The low will act to push the down stream ridge further east,
allowing the persistent upper level low that has been dominating
the area the past couple of weeks to move east. This will allow a
more progressive pattern to set up across the region next week
into the following weekend. A ridge will move over the southern
mainland by Wednesday bringing a brief break in the weather before
another broad low moves in from the Bering Thursday bringing
another round of typical wet August weather to the region. Models
begin to diverge after this point with the EC quickly moving the
low east while the GFS keeps it somewhat stationary over the
Eastern Bering/Western Alaska. There is some consensus that
another ridge builds in over the mainland by next weekend but
obviously a lot can change in 7 days. Regardless, the region will
continue to see periods of cloudy and wet weather though intermixed
with brief breaks.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Storm Warning 150 155 170 172 174
Gale Warning 130 131 132 137 138 160 165 171 173 176 180.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...AH
SOUTHCENTRAL ALASKA...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DEK
LONG TERM...KVP