Small Craft Advisory 193, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
455 PM AKST Wed Feb 26 2020

.ANALYSIS AND UPPER LEVELS...
There is an upper level low in the northern Gulf. Moisture is
rotating around this low, bringing showers mainly to areas near
the Gulf with little precipitation making it inland. There is a
large low over the Aleutians and southern Bering Sea, bringing
some precipitation to that area. Northeast winds are over most of
the Bering, with high pressure over the northern Bering. Surface
high pressure is over much of mainland Alaska, bringing northerly
winds to most of southern Alaska.

&&

.MODEL DISCUSSION...
The numerical models are in good agreement through Friday
afternoon. After this,there just begins to be some differences in
the location of a low moving up from the south towards the
western and central Aleutians. Forecast confidence is higher than
normal.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.

&&

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

Low pressure centered over the Northeast Gulf this evening remains
nearly stationary through Thursday afternoon. Meanwhile, a ridge
resides over the interior keeping the inland locations dry and
clear. The weather across the interior tonight through Thursday
night stays relatively quiet. Increased gusty winds through
channeled terrain picks up late Thursday night as an upper level
short wave dives south out of the Arctic toward the Gulf. This
forces the cold pool from the interior into a drainage pattern
through the Alaska Range. Gusty flow along the northern Susitna
Valley, Matanuska Valley, western Prince William Sound, Kenai
Peninsula and Thompson Pass should peak during the day Friday
before tapering down overnight.

The next front is on tap to push across the western Gulf early
Saturday spreading precipitation across all of Southcentral
through Saturday night. The eastern Kenai, Prince William Sound
and northeast Gulf coast will see the highest precipitation with
this system, although the region could see significant snow
totals as the subtropical jet noses from the North Pacific to the
southern mainland. There is still some uncertainty on the timing
of the boundary with it expected to arrive at Kodiak Island mid
Saturday morning, moving across the Kenai during the afternoon
then advances across the rest of Southcentral during the evening.
Precipitation types will mainly be snow, however snow could change
over to rain across the Gulf with coastal locations along the Gulf
starting as snow possibly mixing with rain or changing over
completely late Saturday night.

&&

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

An area of elongated high pressure across the Northern Bering
continues to hover over southwestern Alaska. Arctic air will
continue to propagate into the southwest with light northerly
flow. Expect temperatures to be cool and dry through Friday
afternoon.

&&

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

There is a broad, decaying surface low southeast of Adak this
afternoon. The front associated with this has moved north past
Saint Paul. This leaves behind a showery pattern over most of the
Bering and the Aleutians. This low will continue to weaken as it
moves towards the Alaska Peninsula Thursday afternoon. A front
associated with a new low from the North Pacific, late Thursday
to early Friday morning, is expected to enter the Aleutian waters
south of Adak. This low will move quickly, as it has upper level
support, and rapidly strengthens. Expect high end gale force
winds, high seas and precipitation across the western and central
Aleutians and Bering through Fri afternoon.

&&

.MARINE (Days 3 through 5 Sat through Mon)...
A strong low in the Bering on Saturday will bring widespread gale
force winds across the Bering, Aleutians, and westward to near
Kodiak Island. Storm force winds are expected closer to the low
center, over the western Bering and central/western Aleutians.
There is an outside chance of hurricane force winds on the
backside of this system. By Sunday this system will weaken, with
gales confined to the central/western Aleutians and the western
Bering. For the Gulf, on Sunday and Monday westerly winds will be
near gale force.

&&

.LONG TERM FORECAST (Days 4 through 7 Sun through Wed)...
On Sunday there will be a low in the Bering, with a trough
extending northeast into northern Alaska. Southwesterly flow aloft
will be over all of southern Alaska, extending westward through
the eastern and central Aleutians. Through Monday the models are
in fairly good agreement that the Bering low will weaken and
slowly drift south, while the northern Alaska trough drops
southward into southern Alaska. By Tuesday the deterministic
models diverge significantly on where the Bering low goes, and
also on how the upper level pattern develops over Alaska in
general. Therefore for Tuesday and Wednesday ensemble mean
forecasts are preferred, and forecast confidence is somewhat low.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warnings 127
		 Heavy Freezing Spray Warning 179 185 412 414
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...BL
SOUTHCENTRAL ALASKA...KH
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CK
MARINE/LONG TERM...BL