Small Craft Advisory 634, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion...CORRECTED
National Weather Service Anchorage AK
651 AM AKDT Sun Aug 27 2017

.ANALYSIS AND UPPER LEVELS...
The upper level pattern this morning continues to be
characterized by a rather diffuse longwave trough over mainland
Alaska, which is anchored by a pair of weak lows near the AK
Peninsula and over the northern Gulf. Broad cyclonic flow beneath
the trough is supporting scattered showers across the southern
mainland. Farther west, a weak frontal zone spans much of the
southern Bering Sea from the Kamchatka Peninsula all the way to
near Dutch Harbor, with a weak wave forming along the front
helping to enhance rainfall over portions of the Eastern
Aleutians. The rest of the Bering remains in a benign cloudy
regime on the southern periphery of a large closed high over
Eastern Russia.

&&

.MODEL DISCUSSION...
Models are in generally good agreement through the short term as
the trough lingers over the mainland and is eventually reinforced
by a shortwave tracking rapidly across the southern Bering. There
is also good agreement on the timing of the next front arriving
along the Gulf coast late Monday afternoon into Monday evening.
Spread starts to increase by Tuesday as a deep North Pacific low
tracks near Kodiak Island. Primarily utilized the GFS for its run
to run consistency with this feature, avoiding the NAM as it has
been a significant outlier.

&&

.AVIATION...
PANC...VFR conditions will persist through Monday morning.
Gusty southeast winds are expected to subside this morning, but
may return to the terminal during the afternoon as ridging builds
along the coast.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...

Similar weather pattern to yesterday over Southcentral Alaska
with some showers around, but also some brief breaks in the clouds
as well. The pattern will begin to change again Monday afternoon
as a strong front pushes into the northern Gulf of Alaska and
brings rain back to that region. Inland areas will see rain push
into those areas Monday night into Tuesday. Winds will also get
gusty around the north Gulf Coast and Kodiak with a northerly
gradient over Cook Inlet bringing Gale force winds to the lower
Inlet by Monday night. It is also looking increasingly likely that
there will be some Storm Force winds developing along the Gulf
coast side of the Kenai Peninsula and into the Barren Island
region by Monday night.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...

Rain showers have become quite sparse across Southwest Alaska this
morning as the orientation of the upper level trough is keeping
the bulk of the energy over the eastern Bering Sea. A few showers
have continued along the Alaska and Aleutian Ranges but those have
been diminishing through the morning hours and should continue to
do so throughout the day. Isolated thunderstorms could develop
near the Kilbuck Mountains this afternoon but instability looks
rather marginal. Through Monday, isolated to scattered showers
can be expected across the region but the lack of any large scale
features should really inhibit any significant rain chances.
Attention will turn to the low moving into the northern Gulf of
Alaska near Kodiak Island late Monday which will push a front into
Southwest Alaska and bring some pretty decent rainfall to the
Bristol Bay area and the Alaska Peninsula.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

A weakening front remains draped across the western half of the
Bering Sea this morning with a triple point low developing west of
Nikolski. This low will help bring some moderate to heavy rainfall
to parts of the eastern Aleutians this morning before it quickly
pushes into the North Pacific. The area of low pressure the
aforementioned front is attached to will begin to move across the
Bering Sea on Monday which will help increase rain chances once
again. Winds look to remain below 25 kts for most locations as
broad surface low pressure encompasses a vast majority of the
Bering Sea.

&&

.LONG TERM FORECAST (Days 3 through 7)...
The long term will begin mid week and will be characterized
primarily by a low south of Kodiak Island that will have moved
into the area from the south. It's front will push in over
Southcentral Alaska in the Monday night time frame. The low will
then slowly track north bringing continued southeast flow and rain
to southern Alaska, with the heaviest along the north Gulf coast.
On Friday the low will dissipate and a new low will push into the
Bering Sea from the west.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE
MARINE...GALE WARNING 119 131 132 150
FIRE WEATHER...NONE

&&

SYNOPSIS AND MODEL DISCUSSION...CB
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MMC
LONG TERM...DWK