Heavy Freezing Spray Warning 1, NWS Anchorage, AK

289 
FZAK62 PAFC 041219
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
319 AM AKST Mon Jan 4 2021

Offshore Waters Forecast for the Bering Sea

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.

PKZ499-050230-
319 AM AKST Mon Jan 4 2021
.SYNOPSIS FOR CENTRAL BERING SEA...

A 968 mb low at 53N 178E moves to 48N 164W at 979 mb Tue morning
and becomes absorbed into a North Pacific low. A 976 mb low at 56N
169W Tue afternoon moves to 54N 170W at 978 mb by Tue night.

$$

PKZ411-050230-
Bering Sea Offshore West of 180 and East of the International
Dateline-
319 AM AKST Mon Jan 4 2021

.TODAY...NE wind 15 to 30 kt. Seas 11 to 18 ft. Snow showers.
.TONIGHT...NE wind 15 to 25 kt. Seas 13 ft. Freezing spray.
.TUE...N wind 15 to 25 kt. Seas 11 ft. Freezing spray.
.TUE NIGHT...N wind 10 to 25 kt. Seas 8 to 11 ft.
.WED THROUGH THU...W wind up to 15 kt. Seas 5 to 10 ft.
.FRI...E wind 20 to 35 kt. Seas 8 to 13 ft.

$$

PKZ412-050230-
Bering Sea Offshore 171W to 180 and North of 56N-
319 AM AKST Mon Jan 4 2021

.TODAY...NE wind 15 to 30 kt. Seas 11 to 14 ft. Freezing spray.
Snow showers.
.TONIGHT...NE wind 25 kt. Seas 12 ft. Freezing spray. Snow
showers.
.TUE...NE wind 30 kt. Seas 10 to 13 ft. Freezing spray. Snow
showers.
.TUE NIGHT...NE wind 20 to 30 kt. Seas 10 to 13 ft.
.WED...N wind 10 to 25 kt. Seas 6 to 11 ft.
.THU...W wind 10 kt. Seas 3 to 6 ft.
.FRI...SE wind 10 to 25 kt. Seas 3 to 7 ft.

$$

PKZ413-050230-
Bering Sea Offshore 171W to 180 and South of 56N-
319 AM AKST Mon Jan 4 2021

.TODAY...NW wind up to 10 kt becoming N in the afternoon. Seas 8
to 12 ft.
.TONIGHT...N wind 10 to 20 kt. Seas 8 to 12 ft.
.TUE...N wind 15 to 25 kt. Seas 8 to 11 ft.
.TUE NIGHT...N wind 10 to 25 kt. Seas 8 to 13 ft.
.WED...NW wind 10 to 25 kt. Seas 7 to 12 ft.
.THU...SW wind up to 15 kt. Seas 4 to 8 ft.
.FRI...SE wind 30 to 45 kt. Seas 8 to 13 ft.

$$

PKZ414-050230-
Bering Sea Offshore East of 171W-
319 AM AKST Mon Jan 4 2021

...HEAVY FREEZING SPRAY WARNING TODAY...

.TODAY...NE wind 10 to 25 kt. Seas 7 to 11 ft. Heavy freezing
spray.
.TONIGHT...NE wind 10 to 20 kt. Seas 6 to 9 ft. Freezing spray.
.TUE...N wind 15 to 25 kt. Seas 6 to 9 ft. Freezing spray.
.TUE NIGHT...N wind 20 to 30 kt. Seas 9 ft.
.WED THROUGH THU...NW wind 15 to 30 kt. Seas 7 to 12 ft.
.FRI...E wind up to 20 kt. Seas 3 to 7 ft.

$$

235 
FZAK62 PAFC 050016
OFFALU

Offshore Waters Forecast
National Weather Service Anchorage AK
316 PM AKST Mon Jan 4 2021

Offshore Waters Forecast for the Bering Sea

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.

PKZ499-051500-
316 PM AKST Mon Jan 4 2021
.SYNOPSIS FOR CENTRAL BERING SEA...

A 971 mb low at 51N 178W moves to 49N 165W at 978 mb by Tue 
morning and becomes absorbed into a North Pacific low. Northerly 
flow will persist over the Bering through Wed afternoon.

$$

PKZ411-051500-
Bering Sea Offshore West of 180 and East of the International
Dateline-
316 PM AKST Mon Jan 4 2021

.TONIGHT...NE wind 15 to 25 kt. Seas 13 ft. Freezing spray.
.TUE...N wind 15 to 25 kt. Seas 11 ft. Freezing spray.
.TUE NIGHT...N wind 10 to 20 kt. Seas 9 ft.
.WED...NW wind up to 15 kt. Seas 6 to 9 ft.
.WED NIGHT...W wind up to 15 kt. Seas 6 ft.
.THU...W wind up to 15 kt. Seas 5 ft.
.FRI...E wind 20 to 35 kt. Seas 8 to 13 ft.
.SAT...E wind 20 to 35 kt. Seas 15 to 23 ft.

$$

PKZ412-051500-
Bering Sea Offshore 171W to 180 and North of 56N-
316 PM AKST Mon Jan 4 2021

.TONIGHT...NE wind 25 kt. Seas 12 ft. Freezing spray. Snow
showers.
.TUE...N wind 20 to 30 kt. Seas 12 ft. Freezing spray. Snow
showers.
.TUE NIGHT...N wind 15 to 30 kt. Seas 9 to 13 ft. Freezing spray.
.WED...N wind 10 to 25 kt. Seas 6 to 10 ft.
.WED NIGHT...NW wind up to 15 kt. Seas 4 to 7 ft.
.THU...NW wind up to 15 kt. Seas 3 to 6 ft.
.FRI...SE wind 10 to 25 kt. Seas 3 to 7 ft.
.SAT...NE wind 30 kt. Seas 11 to 19 ft.

$$

PKZ413-051500-
Bering Sea Offshore 171W to 180 and South of 56N-
316 PM AKST Mon Jan 4 2021

.TONIGHT...N wind 10 to 25 kt becoming 20 kt after midnight. Seas
8 to 13 ft.
.TUE...N wind 15 to 25 kt. Seas 11 ft.
.TUE NIGHT...N wind 25 kt becoming 15 to 30 kt after midnight.
Seas 9 to 14 ft. Freezing spray.
.WED...NW wind 15 to 30 kt. Seas 9 to 14 ft.
.WED NIGHT...W wind 10 to 20 kt. Seas 6 to 9 ft.
.THU...W wind up to 20 kt. Seas 4 to 7 ft.
.FRI...SE wind 30 to 45 kt. Seas 8 to 13 ft.
.SAT...E wind 30 to 40 kt. Seas 17 to 23 ft.

$$

PKZ414-051500-
Bering Sea Offshore East of 171W-
316 PM AKST Mon Jan 4 2021

.TONIGHT...NE wind 10 to 25 kt. Seas 6 to 9 ft. Freezing spray.
Snow.
.TUE...N wind 10 to 25 kt. Seas 5 to 9 ft. Freezing spray.
.TUE NIGHT...N wind 15 to 25 kt. Seas 7 to 10 ft. Freezing spray.
.WED...N wind 20 to 30 kt. Seas 8 to 11 ft.
.WED NIGHT...NW wind 15 to 30 kt. Seas 6 to 11 ft.
.THU...N wind 15 to 30 kt. Seas 4 to 9 ft.
.FRI...E wind up to 20 kt. Seas 3 to 7 ft.
.SAT...NE wind 20 to 30 kt. Seas 6 to 11 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
424 AM AKST Sun Jan 3 2021

.ANALYSIS AND UPPER LEVELS...

A strong upper level low was present this morning over Mainland
Alaska with the center of it just west of For Yukon. Farther south
across Southcentral and the Copper River Basin, a weak upper level
ridge was oriented from northwest to southeast. Low level
moisture trapped beneath an inversion was keeping low stratus and
fog present across the Anchorage Bowl, inland portions of the
Kenai Peninsula along the Sterling Highway east of Kenai, and the
Copper River Basin. Areas where the sky is clear across the
Susitna Valley and where winds are calm, a decent radiational
cooling setup is in place causing temperatures to fall well below
zero. Skwentna so far this morning has dropped to a frigid -28
degrees Fahrenheit.

Southwest Alaska also remains under this weak upper level ridge
with a mostly clear to partly cloudy sky across much of the area.
As a result, temperatures across a decent part of the area are
also below zero with Sleetmute falling to -25 degrees Fahrenheit
late last evening. Bethel is also below zero with temperatures
around -5 degrees. The cold air mass has even reached the Bristol
Bay Coast with Dillingham bottoming out at -2 degrees so far.

For the Bering Sea and Aleutians, a broad upper level trough
remains in place with an associated surface low north of Amchitka.
This is still the same low that broke the mean sea level pressure
record for Alaska a couple days ago to end 2020. As a result,
windy conditions continue across the Bering with occasional
snow/rain showers. The jet stream remains well south of Alaska
keeping the storm track mainly south of the area.

&&

.MODEL DISCUSSION...

Models remain in fairly good agreement on the synoptic scale
features for much of today through tonight and into the first part
of Monday except for fog and low stratus that will continue to be
a forecasting challenge on figuring out whether or not this will
abate today and allow for improving conditions before the next
system moves in for tonight. Beyond Monday afternoon, details
continue to remain fuzzy with how the upper levels move certain
features. The Canadian is the most bullish with the system with an
initial band moving through Anchorage before a lull sometime
Monday evening before it brings the band back through with more
snow. The NAM, GFS, and EC seem to show a one time through and
done with the heaviest occurring north and west of Anchorage
across the Susitna Valley near Skwentna. Nevertheless, the
forecast remains challenging Monday afternoon on. Therefore, the
forecast confidence remains moderate to low for this time frame.

&&

.AVIATION...
PANC...Fog and stratus remains over the terminal this morning
keeping the LIFR/IFR conditions. The terminal is on the edge of
this low stratus and fog, therefore, any push of the fog to the
east will bring the terminal back to VFR conditions as it is
fairly clear to the west but expect the LIFR conditions to remain
prevalent. Winds remain light out of the northeast but just
enough to keep the terminal more in the LIFR/IFR conditions rather than
VFR conditions. Later on in the forecast package, some light snow
is expected to move over the terminal this evening that will keep
low visibilities and keep ceilings mainly in the IFR/MVFR
category.

&&

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

Strong temperature inversions inland across Southcentral will
weaken today and this evening as higher clouds move across the
region. As as result, widespread low stratus and fog over the
Copper River Basin, and spottier conditions from the Western Kenai
Peninsula to the Anchorage Bowl will lift some. That said, the
Copper River could hold onto some lower conditions through
tonight.

The synoptic pattern becomes more active later today through
Monday night. An upper short wave in combination with a surface
low south of the Kenai Peninsula will lift north. Snow will spread
to the Southern and Eastern Kenai Peninsula with rain and snow
along the North Gulf Coast today with snow spreading inland across
the Anchorage Bowl and MAT-SU Valleys tonight. The brunt of the
precipitation will generally be along the coast with the Eastern
Kenai Peninsula receiving several inches of snow. Snow will not
be as heavy tonight across the Anchorage Bowl/MAT-SU Valleys with
only a couple of inches possible. Perhaps a little more in the
upper stretches of the Susitna Valley as snow could linger into
the mid morning hours Monday.

The forecast for Monday becomes more challenging as models differ
on the handling of the synoptic pattern. There is general
agreement of another upper short wave lifting north toward
Southcentral on Monday afternoon. The difference is the timing of
a weakening front heading west across the Gulf. The snow forecast
hinges on the timing of this feature as it will be the primary
moisture source. Current thinking is that this feature will move
far enough west Monday afternoon to bring steady snow the Kenai
Peninsula(mainly eastern) which should spill over into the
Anchorage Bowl/MAT-SU Valleys during the late afternoon and
evening hours bringing accumulating snowfall. Again, the timing of
moisture band and positioning are still a work in progress, so
stay tuned for updates.

&&

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

Upper level ridging will continue to dominate Southwest Alaska
with cold temperatures the next couple of days. A weak front will
approach from the Bering Sea Sunday night and Monday which will
bring a chance of snow near coastal areas. Tuesday another ridge
builds across the area with clearing skies and drier conditions.

&&

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

Low pressure continues to spin north of Amchitka Island and will
very slowly move west on Sunday and then take a dive southward
across the western Aleutians Sunday night and Monday morning. This
system will continue to bring Gales to the western Bering and
western Aleutians, and spawn snow showers across a good portion
of the Bering Sea and Aleutian Islands. On Monday and Tuesday
this low will weaken and say goodbye to the area as it moves south
of the Aleutians. Colder air will spill down from the Arctic
across the Bering Monday into Tuesday as northerly flow develops
with snow showers across much of the area.

Finally, another developing low pressure over the North Pacific
will move north and east, south of the eastern Aleutians and
AKPEN. This system will bring increasing rain to this area with
Gale force winds on the Pacific side. There is still a good amount
of model spread with this system especially on how far north it
will go. If it takes a more northern track, which seems less
likely, it will impact the eastern Aleutians and AKPEN with
stronger winds and more precipitation.

&&

.MARINE (Days 3 through 5: Tuesday through Thursday)...

Gulf of Alaska:

A North Pacific low enters the Southeast Gulf and moves west
across the Gulf through Thu. Model track and development vary, but
confidence is good for widespread Southeasterly small craft winds
and waves with gale force gusts, particularly near capes. This
extends across the Gulf and diminishing for late Wed.

Aleutians/Bering:

Weak high pressure pushes across the Bering and Aleutians through
Thu. Generally Northerly winds 20 knots or less expected over
open waters. Locally gusty winds can occur near channeled terrain.
Waves to 15 feet over the Western Bering, diminishing Wed and to
12 feet from the Eastern Aleutians into Bristol Bay through Thu.

A strong low south of the Aleutians and Alaska Peninsula moves
east through Thu. Model track and development are mixed, but
confidence is good for widespread Easterly small craft winds and
waves with gale force gusts and seas to 18 feet to move with the
low diminishing from the west through Thu.

&&

.LONG TERM FORECAST (Days 4 through 7: Tuesday through Friday)...

Forecast confidence remains moderate overall in the long term.
Model guidance continues to depict a quiet interior, same for the
Bering Sea. So, confidence is increasing for both of those areas
for mid to late next week. Confidence drops with the low in the
Gulf of Alaska, with similar issues to yesterday...keeping
moderate confidence. Both the GFS and ECMWF maintain a low
tracking generally north into the Gulf Tuesday into Wednesday with
an associated frontal system that looks to reach the Southcentral
Coast. However, placement of features in the Gulf prior to this
low's arrival are suspect, which sets the long term up poorly.
The GFS and ECMWF continue to differ on the track of this mid week
low, with the GFS pushing the low center farther inland. So, as
with yesterday we are confident of low pressure in the Gulf of
Alaska mid to late next week. However, with disagreement still in
the low track we cannot with confidence say anything beyond that.
It looks like resolving the weather forecast for the Gulf and
coastal areas of Southcentral will have to wait until the short
term. The rest of our forecast area can expect calm weather.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Dense Fog Advisory 101
Wind Chill Advisory 131.

MARINE...Gale Warning 411 412 413 175
177 178 185 119
Heavy Freezing Spray 160 180 181 185.

FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MV
SOUTHCENTRAL ALASKA...RMC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...RC
MARINE/LONG TERM...MK/BB