Storm Warning 26, NWS Anchorage, AK

106 
FZAK61 PAFC 251306
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
406 AM AKST Tue Feb 25 2020

Offshore waters forecast for the Gulf of Alaska West of 144W

Wind forecasts reflect the predominant speed and direction
expected. Sea forecasts represent an average of the highest
one-third of the combined wind wave and swell height.

PKZ399-260215-
406 AM AKST Tue Feb 25 2020
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...

A 973 mb storm force low at 53N 153W moves to 56N 148W at 983 mb
by Wed morning then moves to 59N 146W at 991 mb by Thu morning.

$$

PKZ351-260215-
Gulf of Alaska Offshore North of 57N and West of 144W-
406 AM AKST Tue Feb 25 2020

...GALE WARNING TODAY...

.TODAY...E wind 30 to 45 kt. Seas 22 to 27 ft. Rain.
.TONIGHT...SE wind 15 to 30 kt. Seas 15 to 27 ft. Rain.
.WED...S wind 10 to 25 kt. Seas 14 to 20 ft.
.WED NIGHT...SW wind 10 to 25 kt. Seas 8 to 16 ft.
.THU THROUGH SAT...SW wind 15 to 30 kt. Seas 6 to 11 ft.

$$

PKZ352-260215-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
406 AM AKST Tue Feb 25 2020

...GALE WARNING THROUGH WEDNESDAY...

.TODAY...SE wind 20 to 35 kt. Seas 19 to 27 ft. Rain.
.TONIGHT...S wind 20 to 35 kt. Seas 16 to 26 ft.
.WED...SW wind 20 to 35 kt. Seas 15 to 23 ft.
.WED NIGHT...SW wind 10 to 25 kt. Seas 8 to 16 ft.
.THU THROUGH FRI...W wind 10 to 25 kt. Seas 9 to 16 ft.
.SAT...SW wind 10 to 25 kt. Seas 8 to 13 ft.

$$

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

.ANALYSIS AND UPPER LEVELS...

A stacked low southwest of Dutch Harbor remains mostly stationary
with a persistent upper level ridge just to its east. Some upper
level clouds have managed to push northward under the ridge, as
well as some gusty winds in the Pribilofs. An upper level trough
is moving out of eastern Alaska and high pressure resides over
much of Southcentral Alaska.

&&

.MODEL DISCUSSION...

Models are still having challenges with placement of the low as it
moves into the Gulf of Alaska. Solutions are quite divergent as
early as Monday evening. However, by Wednesday morning a better
agreement seems to develop in placing the low off the southeast
corner of Kodiak Island.

&&

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

&&

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

Gusty winds continue this morning at Thompson Pass, with winds
reaching near 50 mph during the last few hours. That said, web cam
images from earlier today showed no blowing snow concerns.
Otherwise, the weather remains quiet for most of south central,
with cold air entrenched. That said, things will change for a few
locations. The first of which will be Kodiak, where a rapidly
deepening low will approach Kodiak Island from the south, with
winds rapidly increasing through today. Snow will also move into
the region, with blowing snow becoming a concern. Fairly decent
snowfall rates developing later tonight will allow visibilities to
be reduced to 1/2 mile or less at times, with 6 to 10 inches of
accumulation expected.

Then, as the low approaches a front will swing up towards the Gulf
coast on Tuesday. Overrunning precipitation will allow for
widespread snowfall to develop, reaching Thompson pass
by the late morning hours. Winds will funnel through the pass with
gusts in the 60 to 65 mph range possible, which will drop
visibilities significantly. As such, a winter storm watch for
potential blizzard conditions has been issued.

&&

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

Relatively cold and quiet conditions will persist across
Southwest Alaska, which remains under an upper level ridge today.
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 Alaska Peninsula late this evening and
throughout the day Tuesday as this front moves across the region.
Little snow accumulation is expected. The remainder of
Southwest Alaska, from King Salmon northward will remain dry
through Tuesday night as clouds move in across all of the Southwest
mainland through Wednesday. As winds begin to increase in the
Kuskokwim Delta region, cold wind chills near 20 below zero
return. However, without the frigid cold temperatures in place,
wind chill will stay well below advisory criteria.

&&

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

As one storm force low south of Dutch Harbor departs back into
the North Pacific this morning, another storm force low quickly
moves to south of the eastern Aleutians by this afternoon. This
will keep widespread snowfall and blowing snow along the eastern
Aleutians through Tuesday evening, when strong winds and snowfall
begins to taper off. Dutch Harbor can expect to see around 8+
inches of wet snow over the next 36 hours. Gusts of 45-55 mph will
likely cause periods of reduced visibility in blowing snow
conditions. The remainder of the Aleutians and Bering Sea south of
the Pribilofs will continue to see light rain and snow showers
through Wednesday.

&&

.MARINE (Days 3 through 5: Wednesday through Friday)...

Bering and Aleutians...

A relatively quiet period is expected for the second half of the
workweek. Northeasterly gales will be ongoing Wednesday morning
across the offshore waters of the Bering west of St Matthew Island
and the Pribilofs. The winds will rapidly diminish Wednesday
night. No gales are expected anywhere on Thursday. A strengthening
North Pacific low will approach the Central and Western Aleutians
Friday afternoon and evening. This will cause widespread easterly
gales across the islands. The gale force winds will spread north
and east over much of the rest of the Bering as the low continues
to strengthen Friday night. Large differences in the models on
where and how strong the low will be Friday night make going into
any detail beyond that imprudent.

Western Gulf of Alaska...

A weakening low over Kodiak Island Wednesday morning may be
continuing to produce a few isolated gales in the windier spots,
but winds will quickly diminish below gale force by noon. A North
Pacific low will move into the eastern Gulf Thursday morning, but
with the strongest winds expected south and east of the low
center, only very isolated gales west of the low center are
possible briefly Thursday morning. No gales are expected elsewhere
in the Western Gulf through Friday.

&&

.LONG TERM FORECAST (Days 3 through 7: Wednesday through Sunday)...

A relatively quiet start to the long-term forecast period will
turn much more active towards the weekend. A broad weak trough of
low pressure stretching from Southwest Alaska to west of Adak and
everywhere between will be in place Wednesday morning. This will
keep strong northeasterly winds bringing cold air southwestward
across the western Bering. Meanwhile southerly onshore flow across
the Gulf will keep the weather relatively warm and unsettled with
widespread snow shower activity, especially along the coast of
Southcentral.

The broad trough will shrink and shift eastward by Thursday,
allowing the winds across the Bering to relax. Clouds and
scattered snow showers will persist across the southern mainland,
but none of that activity will be organized or hazardous. The
surface low will shift to Prince William Sound on Friday, but once
again, with everything really weak, light winds and scattered snow
showers will persist in Southcentral. High pressure builds across
Southwest Alaska and the eastern Bering. That high will push east
into Southcentral by Saturday.

A strong North Pacific low will move into the western and central
Aleutians Friday afternoon and evening. This low will be the
catalyst for a return to strong winds, lots of clouds and
precipitation, and warmer temperatures by Sunday. The low will
track northeastward into the Bering on Saturday, with a lot of
disagreement on where it tracks on Sunday. There is much better
agreement that its leading front will spread north across all of
the southern mainland this weekend, reaching Southwest Alaska late
in the day on Saturday, then spreading eastward from there.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Storm Watch 131
         Winter Weather Advisory 171
MARINE...Storm Warning 131 132 136 138 150 352
         Gale Warning 119 120 127 128 130 137 139 155 160 165 170
                      171 172 173 178 351 414
         Heavy Freezing Spray Warning 119 139 179 185 414
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...LTB
SOUTHCENTRAL ALASKA...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AH
MARINE/LONG TERM...JW