Brisk Wind Advisory 38, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
520 PM AKST Mon Feb 24 2020

.ANALYSIS AND UPPER LEVELS...
There is an east to west oriented upper level ridge over southern
Alaska and the central to northern Bering Sea. An upper level
trough is generally to the south of this ridge, with the axis
stretching from just south of the Aleutians into the southern Gulf
of Alaska. Surface high pressure is generally over mainland
Alaska, with low pressure to the south. This is resulting in
generally offshore winds across Southern Alaska, and easterly
winds over most of the Bering and Aleutians. A strong surface low
is currently well south of Kodiak Island, and moving northward.
Several surface lows are south of the Aleutians.

&&

.MODEL DISCUSSION...
The numerical models are in good agreement through Wednesday
afternoon. There is still some minor disagreement on the location
of the surface low in the Gulf on Wednesday, but much less than in
previous model runs. This disagreement will make it challenging to
nail down some of the specific sensible weather details associated
with this storm.

&&

.AVIATION...
PANC...VFR conditions will persist. North winds will increase
through Tuesday morning, and may be gusty at times.

&&

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

The most impactful storm expected this week will bring gusty
winds, snow and rain to the Gulf and surrounding coasts starting
tonight. Inland areas will stay on the dry side with gusty winds
increasing for north to south oriented gaps channeled through
terrain. The associated front moves across Kodiak Island to the
Central Gulf waters this evening. Precipitation will start out as
snow then eventually mix with rain on Tuesday, although the
central Gulf waters should change over to all rain as soon as the
front pulls across. Kodiak Island is expected to receive moderate
to heavy snow as the frontal occlusion slowly sets up a boundary
which stretches along a line from Kodiak City to Middleton Island
Tuesday morning. There is some uncertainty on how quickly the
lowest levels will warm, but the change over to mixed
precipitation is currently expected to occur after the noon hour
Tue. Ongoing snow and rain continues across Kodiak Island through
Wednesday with this system.

The front drapes across the western Gulf to Prince William Sound
and Northeast Gulf Tuesday afternoon and stalls through Thursday. Storm
force winds across the Gulf taper down to gales by late Tuesday
afternoon. Storm force winds across the Barren Islands to Shelikof
Strait persist through late Tuesday evening before trending down.
Snow will mix with rain along the the coastal locations with the
highest accumulations along the eastern Kenai Peninsula and
western Prince William Sound. While the front remains over the
coastal locations, the associated surface low slowly tracks north
with the 980 mb center just east of Kodiak Island Wednesday
morning, weakening to 990 mb as it approaches Prince William Sound
Thursday morning.

Inland areas will see warming temperature trends and increasing
clouds Tuesday afternoon through Thursday. A few snow showers pull
inland across the Copper River Valley Tuesday night through
Wednesday with a better chance to see widespread showers across
Southcentral on Wednesday night.

&&

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

As a front in the North Pacific lifts northward, winds will begin
to increase across the Alaska Peninsula and Bristol Bay as the
pressure gradient tightens through Tuesday. Chances for snow and
blowing snow return to the eastern Alaska Peninsula, generally
from Sand Point east, late this evening and throughout the day
Tuesday, with little snow accumulation expected. Blowing snow does
not look to reach advisory criteria as visibilities should remain
above the half mile mark due to the warmer temperatures. The
remainder of southwest Alaska, from King Salmon northward, will
remain dry through Tuesday night. As winds move into the Kuskokwim
Delta region, expect wind chills to return to near 20 below zero.
As the front in the North Pacific continues its northward
propagation, it will also weaken. This will bring calmer and drier
conditions to the Southwest into Wednesday along with warmer
temperatures.

&&

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

A storm force low moves south of the eastern Aleutians with
another low just south of Kodiak Island tonight. A tightened
pressure gradient, between these two lows, will keep widespread
snowfall and blowing snow across the Aleutians through Tuesday
evening. Dutch Harbor is expected to see around 8 inches of snow
over the next 36 to 48 hours. Strong winds and snowfall will then
begin to taper off as this strong pressure gradient propagates
north. Looking ahead to Wednesday, the low over Kodiak will move
northeast and the low south of the eastern Aleutians will move
north. These will continue to weaken and lose their influence,
with calmer and drier conditions expected across the Aleutians and
the Bering through Wednesday.

&&

.MARINE (Days 3 through 5 Thu through Sat)...
Winds look to remain below gale force from Thursday through Friday
morning. Later Friday a strong system will move into the western
and central Aleutians, and into the Bering Friday night and
Saturday. This system will bring gale to possibly storm force
winds across the western and central Aleutians and most of the
Bering Sea. On Friday night there is also a chance of some
westerly gales through the Barren Islands area.

&&

.LONG TERM FORECAST (Days 4 through 7 Fri through Mon)...
On Friday morning the pattern will consist of an eastward moving
trough over western Alaska, an east to west oriented ridge across
the central Bering, and a deep trough southwest of the western
Aleutians. On Friday the western Alaska trough slide east across
the area and weaken. A deep upper low in the western trough will
move northeast into the western Aleutians Friday night then into
the Bering on Saturday. This will turn the flow aloft to southwest
over the eastern Bering through southern Alaska, with a fairly
consolidated jet pushing northward. This will result in a fairly
active pattern Sunday and Monday with the best chance for snow
for the southern mainland this week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory 171. Winter Storm Watch 131.
MARINE...Storm Warning 351 352 130-136 138 150
		 Gale Warning 119 120 127 128 137 138 411 412 155 160 165
					  178 185
		 Heavy Freezing Spray 139 414 179
FIRE WEATHER...NONE.

&&

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