Small Craft Advisory 35, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
447 PM AKST Thu Jan 9 2020

.ANALYSIS AND UPPER LEVELS...
A 1040 mb high is currently centered over the Yukon Territory
with the ridge-axis extending westward through the Alaska
Interior. GOES-17 Water Vapor imagery shows a negatively- tilted
trough extending southeastward from Bristol Bay to 40N 150W. Water
vapor imagery also shows a closed upper-level low drifting
northwestward across the central Bering Sea. ASCAT data shows gale
force winds associated with this low in the central Bering Sea. A
second area of low pressure at 44N 177E is currently moving
northeastward with an occluded front reaching the western
Aleutians. The King Salmon radar shows snow showers moving
southeastward across the Kuskokwim and Kvichak River Deltas.
Middleton Island radar imagery shows snow showers moving
northwestward towards Middleton Island and the northern Gulf of
Alaska. Gusty conditions have been occurring throughout the Valdez
areas with strongest gusts in the Valdez Narrows.

&&

.MODEL DISCUSSION...
Models are in good agreement with the overall synoptic pattern
across the area over the next few days. High resolution models
were favored with respect to the Valdez wind forecast due to them
having a better handle on the smaller-scale local effects compared
to the operational models. Operational models are in agreement
with the predominant storm track across the North Pacific to
remain across the southern Gulf.

&&

.AVIATION...
PANC...While there is some fog around, the northerly winds have
increased over Knik Arm and that is diminishing the extent of it.
This should continue and any fog cover overnight into tomorrow
should be brief.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...

The cold air will persist over Southcentral though the weekend.
Given the extremely cold temperatures to the north and a series of low
pressure systems tracking across the Gulf, gusty northeasterly
winds in terrain gaps will be likely into Saturday. Wind gusts of
60 mph are possible in Valdez Friday morning. Similar gusts are
also possible in Thompson Pass and thus a Wind Chill Advisory is
currently in effect for values near minus 50. Winds in the
Matanuska Valley will potentially cause very sharp temperature
gradients in the Palmer/Wasilla area overnight. Temperatures will
be relatively much higher where winds are stronger due to strong
inversions near the surface. The only notable chance for snow
over the next few days will be in Kodiak with around 1 to 2 inches
possible overnight Friday into Saturday as front tracks across the
Island.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...
(Tonight through Sunday Evening)

A weakening occluded front stretched from near Mekoryuk to Pilot
Point this afternoon, with over-running precipitation in the form
of snow having developed from just southeast of Bethel, to King
Salmon. This will continue through the morning hours, while slowly
diminishing in coverage along this axis, as the front continues to
weaken.

Our attention then turns to a warm front quickly moving into the
region on its heels for Friday afternoon. This front will maintain
its integrity longer, due to a stronger area of low pressure
across the western Bering, helping to provide better warm air
advection aloft. Like its predecessor, snow will break out once
again for the coastal locations, before pushing inland Friday
night, then reaching the central Kuskokwim Valley to Lake Iliamna
area by late Saturday morning. A few inches of snowfall will be
possible with this feature. By Saturday evening, snowfall will
decrease in coverage as the frontolysis (weakening or dissipation
of a front) takes hole, having outrun its better dynamics while
also bumping into a ridge further to the northeast.

These fronts will  help to advect warmer air into
the region, helping to moderate the temperatures a little bit each
day.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...
(Tonight through Sunday Evening)

A rapidly deepening area of low pressure was located just south of
Shemya this afternoon, with its attendant warm front almost on
top of the western Aleutians. This front will race north and east
through Friday, with widespread gale force winds, rain, and snow
accompanying it. This low will also bring storm force sustained
winds, with gusts just under hurricane force likely for the
western Bering and Aleutians, closer to the track of the low.
Here, seas building into the 35 to 40 feet range will just help
make the conditions that much more challenging. These winds and
waves will subside for the weekend, as the low and front lift away
from the region.

&&

.MARINE (Days 3 through 5)...

Sunday into Monday a weak surface low develops and tracks east
across the southern Bering. This will bring gusty northerly winds
across the western waters which may be gale force if the low
deepens more than currently progged. For the Bering on Sunday,
westerly gales start the forecast along the northern waters which
taper down Sunday night. The next North Pacific front moves to the
western and Central Aleutians Monday night bringing max gales
winds and rain across the western waters through Tuesday.

&&

.LONG TERM FORECAST (Days 3 through 7)...

Below normal temperatures and dry conditions continue for much of
the southern mainland in the forecast Sunday through next
Thursday. Gusty offshore flow along the gulf also persists as the
dominant ridge across the interior resides over the the Alcan.
The most active weather focuses over the Bering as new upper level
parent develops over the North Pacific moves to the Kamchatka
Peninsula Sunday night. This gale force systems front maintains
strength as additional energy propagates around the base of its
trough mid week. The southwestern areas of the state are expected
to trend slightly warmer at the beginning of next week as a
subtropical air mass advects northward...however, temperatures
will remain below normal.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Flood Warning 121.
		 Wind Chill Advisory 131.
MARINE...Heavy Freezing Spray Warning 119 121 126 127 129 130 139 141
		 185.
         Storm Warning 411 177 178
         Gale Warning 127 128 130 352 412 413 414 155 165 170 171 172
                      173 174 175 176 179-185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...AP
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD
MARINE/LONG TERM...KH