Small Craft Advisory 791, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
342 AM AKDT Sun Oct 14 2018

.ANALYSIS AND UPPER LEVELS...
After several days of a Bering low dominating the pattern there
looks to be a change with a deep low south of the Aleutians
becoming the focus as the Bering low weakens. The front associated
with the deeper low is starting to push into the Alaska Peninsula
and is bringing rain with it. Further east, over Southcentral
Alaska, weak ridging has moved in which has helped clear out cloud
cover over some areas.

&&

.MODEL DISCUSSION...
The models remain in good agreement with the main synoptic
features through the mid term. However, there are some minor
differences tracking a front through the Gulf today. These
differences look to have little effect on impacts for southern
Alaska with the exception of how much rain Kodiak Island will see.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist. Even though
the setup is decent for fog development with light winds, abundant
low level moisture and ridging overhead, no fog is forecasted at
this time. This is in large part due to the cloud cover over the
area that is inhibiting temps from dropping.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
High pressure will be over the area today, for a period of benign
and dry weather. Southerly flow aloft will return tonight, and
strengthen on Monday. A weak front will approach the north Gulf
coast tonight as this southerly flow begins. This will bring
increasing winds to the Gulf waters, and a chance of precipitation
to the coast. A considerably stronger front will push north to the
coast Monday morning. This will spread rain over most of
Southcentral during the day. The flow aloft will be quite strong,
with a moist "atmospheric river" pointed at the area by afternoon.
Rain will continue over most of the area through Monday night.
Most of the precipitation will be over the coast and coastal
mountains from Prince William Sound eastward, where amounts of two
to five inches are possible Monday and Monday night.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
The frontal system approaching the coast is currently increasing
southeasterly flow across Southwest Alaska. The frontal system
will reach the coast this evening with precipitation spreading
onshore tonight through Monday. As the front nears and moves
onshore, winds will continue to increase, particularly the east-
southeasterly gap winds out of the passes in the Alaska/Aleutian
Range. As the upper level low moves north to become stationary
offshore of southwest Alaska, showery weather will persist through
mid week.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
The strong low south of the Aleutians has now become vertically
stacked near 50N 170W early this morning. The low will continue to
track gradually east northeast through this evening then turn more
northerly tonight, lifting north across the Alaska Peninsula on
Monday. The large low will then become established over the
eastern Bering, in between Bristol Bay and the Pribilof Islands
where it will remain through midweek. Troughs rotating around the
low will bring numerous showers to much of the Bering and
Aleutians, while closer to the center of the low more unstable
air will bring the potential for isolated thunderstorms.

&&

.LONG TERM FORECAST (Days 4 through 7)...

At the onset of the forecast period, the longwave pattern features
ridging over Copper River Basin, a trough over SW Alaska and the
AKPEN, ridging over the western Bering and a new low near Sapporo
Japan. Anticipate a very progressive pattern. By 00z Friday, the
model guidance starts to diverge with the low near Kodiak/AKPEN
and the cyclone near Kamchatka. Given the lack of run to run
continuity and the lack of model consensus, the track and the
timing of both lows is still uncertain. Generally expecting wet
and unsettled weather with both systems. Stay tuned for more
details.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gales...130 131 138 150 155 160 165 170 171 174 175 176
				 177 180 185 414.

&&

SYNOPSIS AND MODEL DISCUSSION...DK
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
LONG TERM...PS