Small Craft Advisory 234, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
441 AM AKDT Fri Mar 17 2017

.ANALYSIS AND UPPER LEVELS...

Little has appreciably changed in the last 24 hours, and the
overall weather pattern continues to feature a highly amplified
ridge of high pressure in the Bering Sea and a deep trough over
the Gulf of Alaska. This sets the southern mainland up under cold
and gusty northerly flow, though these gusty winds have subsided a
bit in the last 12 hours. This downturn has been in response to a
decrease in the active movement of more cold arctic air into the
area, as well as the fact that the series of surface lows moving
near the north gulf coast have moved off to the southeast which
has allowed pressure gradients to relax a bit. Of note, a gale-
force front and rain has moved into the western half of the
Aleutian Chain, and will be parked nearly stationary in that area
for the next few days.

&&

.MODEL DISCUSSION...

The models are in pretty good shape overall. While all models show
the front in the Bering stalling over the next day or so, the NAM
stalls this feature further south and west than virtually all the
other models. Thus the other global models (Canadian and ECMWF)
were the preferred tonight on the west domain. No significant
preference was noted on the eastern domain, and higher resolution
models were used when available to best capture wind patterns
through the highly complex terrain gaps.

&&

.AVIATION...
PANC...Clear skies and generally light northerly winds should
persist throughout the period. There is an outside chance the
north winds could get gusty again for a few hours around the
middle of the day, but at this point the most likely scenario is
that a steady 10 mph or so north wind prevails throughout the
period.

&&

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

Dry and unseasonably cold conditions will persist as a reinforcing
shot of cold air is moving into the area underneath a cold upper
level low. This will keep mostly clear skies over the inland areas
through at least Saturday night.

The gusty (but diminished compared to previous days) outflow
winds along the north Gulf Coast will persist into tomorrow and
the cold air in conjunction with the upper level low will develop
a surface low in the Gulf Saturday. The snow showers with this low
will mainly stay over the Gulf though a few may make it onshore
Saturday night into Sunday depending how this low actually
develops and tracks. It looks unlikely that any snow showers will
make it farther inland than the Gulf Coast mountains.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
At long last the persistent northerly winds are on the decline.
While the reduction in wind will be the continued story for the
Greater Bristol Bay area, a weak front and disturbance will impact
the Kuskokwim Delta. Light snow will continue from this system
through the day today, mainly along the coast. Snow will both move
south and taper off through the overnight hours with minor
accumulations. Otherwise expect well below average temperature,
light northerly winds, and cloud free skies.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
The main feature over the area is a stalling warm/occluded front
over the western/central Aleutians. The gale-force front will
quickly lose its punch as is moves slowly over the chain today.
Light rain will continue until the front passes overnight tonight.
High pressure will control the eastern Bering Sea, but gusty gap
winds will continue near the Alaska Peninsula with heavy freezing
spray for the next couple of days.

&&

.LONG TERM FORECAST (Days 3 through 7)...
The long term forecast will remain fairly unchanged and seemingly
no different than the present weather happening now. Persistent
low pressure across the Eastern Gulf, high pressure across the
interior and low pressure across the Western Bering will be the
key weather players through next week.

Midweek and later, the low pressure across the Gulf will allow
weak showers along the coast while the rest of the region will
remain dry with passing clouds. Far West, and just off the
Kamchatka coast, is a stacked low that will meander within the
Russian vicinity for some time. The main jet focus is far south
and will allow a few weak wiggles in the flow to work around the
stacked system following the weekend and in to the mid week. This
will reinforce a nearly stationary front and allow the occasional
weak maritime gale south of the Aleutian chain.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale 175 176 177 178
         Heavy Freezing Spray 130 138 139 150

&&

SYNOPSIS AND MODEL DISCUSSION...AMD
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MTL
LONG TERM...SS