Heavy Freezing Spray Warning 88, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
454 AM AKST Mon Mar 1 2021

.ANALYSIS AND UPPER LEVELS...

A vertically stacked low over the Bering is producing hazardous
weather conditions across the Bering Sea and Aleutians. A strong
frontal system from the Bering low runs to Southwest Alaska
through Southcentral to the Gulf of Alaska. Colder environmental
air temperatures collaborating with the rapid moving front will
enhance more snow over the region this morning. Meanwhile, warmer
temperatures reported from the eastern Aleutians will keep precip
focused over that area south of Bristol Bay.

&&

.MODEL DISCUSSION...

Overall, models continue to stay in close agreement with the
placement and motion of the large scale weather pattern in the
next couple days. The solutions maintained an east-southeastward
trend for the Bering and it should not come as a surprised as
previous models suggested this similar track. Ultimately, the
Bering low and its frontal system will continue to provide
elevated weather conditions for the region through the next day or
two.

&&

.AVIATION...

PANC...IFR to MVFR flight conditions are expected in response to
the front and possible heavy snow moving across Cook Inlet
through Anchorage this morning. MVFR ceiling will linger over
Anchorage Bowl tonight before the next sequence of snowfall
resumes around 02/1300Z.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2: Today
through Tuesday Night)...

A negatively tilted upper level trough, the leading front of a
strong Bering low, and plentiful moisture are all taking aim at
Southcentral this morning. As of this writing, the Kenai radar is
filling in nicely, with snow ongoing across the Western Kenai
Peninsula. The snow will continue filling in and moving
northeastward as a Gulf low develops along the front near Kodiak
Island this morning. As the low rapidly develops, it will track
south of Seward around midday and move to near the Copper River
Delta this evening. Meanwhile, southwesterly flow in the upper
levels will continue to stream Pacific moisture up Cook Inlet all
day today, until the trough passes this evening. The combination
of the low over the Gulf largely keeping downsloping a non-factor,
and the supportive lift ahead of the upper level trough will keep
steady snow falling all across Southcentral all day today.
Temperatures are starting out the day today largely in the teens
and 20s. Thus, the snow should be a powdery consistency. 3 to 6
inches of snow are likely for most areas, though with some
uncertainty as to what the snow ratios will be, there is potential
for localized accumulations over 6 inches. Since most of the
forcing for the snow should remain from Anchorage south, along
with more plentiful moisture closer to the Gulf, snowfall amounts
will diminish the further north you go.

Behind the storm tonight, the snow will end from west to east this
evening into tonight. Across the Gulf, the weather regime will
turn much more showery behind the storm. This will keep coastal
snow shower activity ongoing into Tuesday night. The chances of
those snow showers reaching inland will diminish with time. Below
normal temperatures will persist into midweek, though gradually
clearing skies are expected through midweek. A secondary surge of
colder air will move in late Tuesday night into Wednesday, which
should continue to dry the area out. Looking ahead, the next
chance of snow for interior areas, including Anchorage, isn't
until Friday morning.

&&

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

The radars at Bethel (PABC) and King Salmon (PAKC) have been
active overnight as the frontal boundary brings a fresh batch of
snow to the region. More snow and blowing snow is expected today
and tonight. A westerly fetch will develop later today for Bristol
Bay and it will persist for almost 24 hrs. The potential for
surging conditions along Bristol Bay is actively being monitored.
Tuesday late morning/ afternoon the main surface low will drop
southward across the Alaska Peninsula and then widespread
northerly winds will ensue.

&&

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

The low in the Bering dove down to 942 mb and now is beginning to
fill. An 89 mph gust was measured at Shemya yesterday afternoon.
Additional hurricane force winds gusts were observed over night.
The surface low is moving across a data sparse area, but looking
at the models strong winds will continue today and tonight. By
midnight the surface low will have weakened to 968 mb-972 mb. Even
at that range the pressure gradient forces will still be strong.
Expect more adverse weather, enhanced seas and heavy freezing
spray for the Bering Sea is anticipated today and tonight. A
triple point low will form over the Bristol Bay/AKPEN region and
then move over Kodiak and away from the eastern Aleutians.

&&

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

Bering: Upper level disturbances move over the Central and
Eastern Bering and Alaska Peninsula. Forecast confidence is good.
Widespread high end gale force winds and waves will diminish Thu.
Waves to 20 feet subsiding. A well developed low and front move
across the Bering from the West through Fri. The front brings
widespread high end gale force winds with areas of storm force
winds to the Central Bering, diminishing late Thu, while the wind
wrapped low holds onto widespread gale force winds through Fri.
Waves building to 26 feet through Fri.

Gulf of Alaska: A low exits the Southern Gulf for Thu, with
outflow winds from the Alaska Peninsula right behind. Models vary,
but confidence is good. Widespread high end gale force winds and
waves spread from the Shumagin Islands to the Barren Islands into
the Western Gulf through Thu. Waves to 17 feet across the Southern
Gulf, subsiding. The next low and front approach the Southwest
Gulf Fri.

&&

.LONG TERM FORECAST (Days 4 through 7: Thursday through Sunday)...

Generally quiet weather is expected for the long term forecast
period, especially across Southcentral. The period is expected to
mainly be dominated by a strong upper level low over northeastern
Russia that will continue to send rounds of Arctic/Siberian air
across much of Alaska especially early on. Upper level ridging
will periodically build north and try to cut off this cold air as
storm systems move north into the Bering and along the eastern
periphery of the upper level low. As a result, a frontal system is
anticipated to move into Southwest Alaska on Thursday with some
snow. However, this front won't have much progress into
Southcentral as another lobe of cold air Will quickly try and push
across southern Alaska behind it. The front will be quickly
pushed southward across the Alaska Peninsula and into the North
Pacific. The main weather concerns for Southcentral will mainly be
the winds through the typical gaps, bays, and passes.
Temperatures are also expected to remain well below normal for at
least the first half of the forecast period with some warming
heading into Saturday and Sunday though remaining either slightly
below or near normal.

Towards the very end of the period on Sunday, models are keying
in on an upper level ridge setting up across much of southern
Alaska as the upper level low over northeastern Russia moves
southward into the western Bering bringing colder air to this area
and starting to bring milder air north into Southcentral. The
storm track looks to also become more active starting Sunday as
another system traverses the Bering and eventually into the Gulf
early next week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...High Wind Warning 185 187
		 Winter Weather Advisory 155
MARINE...Storm Warning 170 171 173-178
		 Gale Warning 119 120 131 132 136 150 155 165 172 179 180
					  185
		 Heavy Freezing Spray Warning 139 150 160 165 179 180 185

&&

SYNOPSIS AND MODEL DISCUSSION...CMB
SOUTHCENTRAL ALASKA...JPW
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PJS
MARINE/LONG TERM...MK/MV

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
333 PM AKST Mon Mar 1 2021

AKZ161-021400-
Bristol Bay-
Including the cities of King Salmon, Dillingham, Naknek,
and Pilot Point
333 PM AKST Mon Mar 1 2021

...BERING STORM WILL BRING ELEVATED WATER LEVELS TO BRISTOL BAY
COAST TONIGHT THROUGH TUESDAY...

A strong low currently centered in the northern Bering has created
a persistent westerly fetch across the southern and eastern Bering
waters. As the low center tracks southward and arrives over the
eastern Bering by early Tuesday, continued westerly winds will
create elevated water levels across the Bristol Bay coast.

Given the lack of shorefast ice in this area, water levels may
reach 2 to 4 feet above Mean Higher High Water (2 to 4 feet above
the normal highest tide line). Elevated water levels are possible
beginning tonight during high tide, and are expected to come back
down during the day on Tuesday.

For the latest information, visit weather.gov/Anchorage.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
344 PM AKST MON MAR 1 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0325 PM     SNOW             UPPER POTTER VALLEY     61.06N 149.76W
03/01/2021  M3.6 INCH        ANCHORAGE          AK   TRAINED SPOTTER

            SPOTTER REPORTED 3.6 INCHES OF SNOW IN THE
            LAST 24 HOURS.

&&

MV