Small Craft Advisory 362, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
431 AM AKDT Thu May 9 2019

.ANALYSIS AND UPPER LEVELS...
A low pressure trough over the Aleutians continues to be coupled
with a high amplitude ridge in the eastern Pacific. This is
providing sustained southerly flow in the Gulf of Alaska and
keeping an active weather pattern for our forecast area. The
latest low that pushed through this afternoon has left some
showery activity behind it in southcentral and southwest Alaska,
but weather is largely clearing out overnight tonight. This will
be short lived as the next area of low pressure can be seen on
satellite undergoing development in the southern Gulf of Alaska.

&&

.MODEL DISCUSSION...
Models are in good agreement through the short term. They are
handling the overall pattern well. They also appear to be doing a
better job of handling the incoming low pressure system into the
Gulf of Alaska on Friday. Therefore, we can increase forecast
confidence in this next system.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist with showers in
the area later in the day. Wind shear will become an issue
tomorrow night.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
A weather front over the northern Gulf will move rapidly northward
today. Rain from this front will reach the northern Gulf coast by
late morning and push inland during the afternoon. Most of the
rain will fall along and near the coast, with cross-barrier flow
limiting amounts inland. The low responsible for this front is
over the southwest Gulf this morning. This low will intensify and
move north during the day today through tonight, reaching Kodiak
Island early Friday morning and pushing into southwest Alaska
Friday afternoon. Gale to storm force winds are expected over the
Gulf with this system. On Friday winds over much of Southcentral
will become quite strong for this time of year as a tight pressure
gradient will exist between this low and high pressure over the
eastern Gulf. There will also be decent chances for rain over the
area with decent moisture and cyclonic flow aloft. Winds will
diminish Friday night as the low moves away to the northwest, but
precipitation chances will continue.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
A front associated with a surface low in the far southwestern
Gulf will rotate west over the Greater Bristol Bay area this
afternoon and evening and over the remainder of Southwest Alaska
tonight spreading clouds and widespread rain with it. The low will
become vertically stacked near Kodiak Island late tonight and
then turn more to the northwest slowly crossing Southwest Alaska
Friday and Friday night, continuing showers across the area.
Showers will diminish somewhat on Saturday before the next front
approaches from the south late Saturday night.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
The broad upper level low will continue to persist over the
Bering through Saturday with smaller circulations spinning around
it and bringing scattered to numerous showers as they rotate
through. One surface low currently north of the western Aleutians
will track east-southeast to the central Aleutians by Friday and
continue east to the eastern Aleutians through Saturday. A trough
associated with the low crossing Southwest Alaska Friday and
Friday night will form into a small surface low near Nunivak
Island on Saturday and rotate southwest towards the Pribilof
Islands through Saturday night. A north Pacific low will approach
the eastern Alaska Peninsula from the south Saturday night.

&&

.MARINE (Days 3 through 5: Saturday through Monday)...

Lingering southwesterly gale force winds in Shelikof Strait and
along the southwestern Gulf coast will subside to small craft by
Saturday morning as the Gulf low lifts northward over southwest
Alaska. By Saturday afternoon, model solutions indicate another
North Pacific low moving into the Gulf, though there is little
agreement on the exact track. This low may introduce the
possibility of another round of gale force winds over the same
area (Shelikof Strait and the southwestern Gulf) Sat night into
Sun morning, however confidence remains low due to uncertainty.
Across the Bering, there is high confidence there will be no
high winds or waves through Monday.

&&

.LONG TERM FORECAST (Days 4 through 7: Sunday through Wednesday)...

Two main features for the long term include a broad upper level
trough over the eastern Bering and a high amplitude ridge over
the Yukon. Although models quickly become inconsistent by Monday,
the general trend shows several upper level waves rotating around
the upper level trough. This will likely perpetuate unsettled
weather conditions over the southern half of the state through
early next week. A possible reprieve from the unsettled weather
may arrive midweek if the ridge over the Yukon maintains its
strength.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Storm: 351 352
         Gale: 119 120 130 131 132 138 139 150
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...BJB
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
MARINE/LONG TERM...PD