Small Craft Advisory 201, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
812 PM AKST Sat Mar 5 2022

.ANALYSIS AND UPPER LEVELS...

A surface low situated just off the northeast Kodiak Island coast
this afternoon is continuing to move toward Prince William Sound.
This low is strengthening as it moves toward the Southcentral
coast, aided by a southerly 100+ kt jet streak and a vigorous
upper-level shortwave moving across Southwest Alaska. Strong lift
and deep moisture advection ahead of this feature produced a band
of locally heavy snow from the western Kenai Peninsula to the
Anchorage Bowl this morning, with 3.5 inches of snow recorded in a
one hour period (9am to 10 am) at the Anchorage NWS office. As of
7pm, 11.7 inches of snow have fallen at the NWS office. Snow is
also falling across the Mat-Su Valleys, albeit lighter in
intensity, as well as in Valdez. Rain is falling along the
immediate coast from Cordova to Whittier and Seward.

To the west, show showers persist across parts of the Kuskokwim
Delta and Bristol Bay, as the shortwave trough moves overhead. A
ridge of high pressure has settled over the eastern half of the
Bering and Aleutians with generally tranquil conditions.

Farther west, a storm-force low is occluding as lifts to over
Shemya and Attu this afternoon. Southerly wind ahead of a cold
front peaked just shy of 60 kt for Adak with winds over 40 kt for
Atka.

&&

.MODEL DISCUSSION...

Models are in good agreement with the overall synoptic pattern and
timing of various waves moving across the region through the next
several days. However, none of the guidance had the initial band
of heavy snow for the Anchorage Bowl. The 12z GEM regional,
though, did place some moderate precipitation across the western
Kenai peninsula, extending up to Anchorage and the Matanuska
Valley. The GEM regional, along with the recent 18z hi- res model
runs, are all indicating that a second round of heavier
precipitation will move back over Anchorage by 00z Sunday and
linger, especially over the eastern half of the city, through 06z.
Thus, there is high confidence that snow will continue from Kenai
north to the Matanuska Valley through this evening with additional
accumulations.

Guidance has also come into better agreement with the timing and
placement of a surface low moving over the AKPen beginning late
Sunday. This feature will weaken as moves north, with mixed
rain/snow for Bristol Bay and light snow for the Kuskokwim Delta.

&&

.AVIATION...
PANC... IFR conditions will prevail through Saturday evening as
snow continues to taper off across the terminal. The snow is
expected to come to an end around 6z Sunday as the storm move
east. This, coupled with a developing northerly wind, should allow
for MFVR, and possible VFR, conditions to return and remain
through Sunday afternoon.

&&

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

Widespread snow will continue across Southcentral Alaska this
afternoon and evening. The snow will be moderate to heavy at
times. For the Anchorage Bowl and Matanuska Valley, the heaviest
snow is expected between 6pm and 9pm AKST. Additional snowfall
accumulations expected are 3-6" for the Anchorage Bowl, 5-10" for
the Upper Hillside due to orographic enhancement and 3-6" for the
Matanuska Valley. A Winter Storm Warning has been issued for the
Anchorage Bowl and Upper Hillside through 1am AKST tonight. A
Winter Weather Advisory has been issued for the Matanuska Valley
through 1am AKST tonight. A Winter Weather Advisory also remains
in effect for the northern Copper Basin (north of Gakona) through
9am AKST on Sunday morning for an additional 5-10" of snow with
localized amounts up to 12".

The snow will then gradually taper off from west to east overnight
tonight and then the main weather focus will be strong off-shore
flow. Colder temperatures over the Copper Basin with a strong
south to north pressure gradient (high pressure over the Alaskan
interior and low pressure over the Gulf of Alaska), strong off
shore flow is expected in the Valdez Arm, Valdez Narrows, Copper
Delta and Thompson Pass. The winds will be strongest from late
Sunday night through mid-day Monday as this period will have the
strongest south to north pressure gradient. These strong winds
will then rapidly ease on Tuesday as the pressure gradients
weaken.

&&

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

Snow is waning over the western slopes of the Alaska/Aleutian
Range this evening as a low pressure system in the northern Gulf
and accompanying upper-level shortwave exit eastward. In their
wake, a ridge of high pressure moves in over Southwest Alaska
tonight, giving way to colder temperatures and clearer conditions.
With clearer skies, dry mid-levels, and light winds, there will be
significant potential for fog to develop over the Kuskokwim Delta
and Lower Kuskokwim Valley. Winds will be a little stronger in the
Bristol Bay region overnight, allowing for more mixing and reduced
potential for fog.

The next low pressure system reaches the AKPEN Sunday night,
bringing mostly snow with some rain possibly mixing in at times.
The low's attendant front reaches the Southwest coast by Monday
and pushes inland through Tuesday, bringing a round of light
snow. Strong southeasterly flow will accompany the front,
resulting in downslope holes in the lee of the Aleutian Range and
the Kuskokwim Mountains. As a result, the heaviest snow is
expected on the eastern slopes of the Kuskokwim Mountains and
along the Kuskokwim Delta coast, where up to 2 inches of snow
should accumulate. There is a slight potential for blowing snow
along the northern Bristol Bay coast with this front as well,
though with temperatures in the 30s, marginal winds of 15 to 25
mph, and light snowfall rates, reductions in visibility are be
likely to be brief and isolated in nature.

&&

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

A storm force low centered near the western Aleutians this evening
will track northward, bringing a swath of southerly gales
northward across the western Bering through Sunday. Its front will
extend across the central Bering/Aleutians, with southerly gales
which diminish tonight. The western Aleutians see a mix of rain
and snow through Sunday morning, while the central Aleutians will
receive primarily rain. A second North Pacific low will track
towards the Alaska Peninsula Sunday night bringing gale force
winds south of the peninsula. Precipitation will begin as snow
for the eastern Aleutians/AKPEN through Monday before
transitioning to rain showers as the low tracks into the eastern
Bering.

&&
.Marine (Days 3 through 5: Tuesday through Thursday)...

Gulf of Alaska: A pair of fronts will move across the Gulf
spreading Gales near Kodiak Island along the Barren Islands and
Shelikof Strait Tuesday and then a barrier jet forming across the
northern Gulf Wednesday into Thursday with gales possible. There
may be a low that develops along the second front Thursday which
could strengthen winds, but low confidence due to model
differences. Seas will generally be between 9-15 feet over open
waters.

Bering Sea: A gale force low near Attu Island with possible storm
force gusts will remain nearly stationary through the period
producing Gales near the western Aleutians and western Bering. It
will push a front across the Bering through Thursday with pockets
of Gales possible near the front. Models indicate that a low will
form along the front somewhere south of the AKPen or the eastern
Aleutians which could enhance winds, however models differ on
strength and timing of this low. Seas will generally be 15 feet or
less across the Bering and 15 to 25 feet near the western and
central Aleutians.

&&

.Long Term Discussion (Days 4 through 7: Wednesday through
Saturday)...

A blocking high anchored across far east Russia just west of the
Bering Strait will remain quasi-stationary through the entire long
term with a ridge extending from it into northern sections of
Alaska. An elongated trough will be positioned across the southern
Bering and Aleutians extending into the Gulf through the period. A
strong ridge will begin over the Gulf on Wednesday and shift into
western Canada Thursday into Friday which will also low and fronts
to enter and progress across the Gulf. As for sensible weather,
fronts and low will be able to bring rain and snow into Southwest
and Southcentral Alaska, but should weaken considerably as they
move inland and encounter high pressure across the interior.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Storm Warning: 101
Winter Weather Advisory: 111 141.
MARINE...Gale: 127 129-132 138 150 155 173-175 177 178 185 411-413.

&&

SYNOPSIS AND MODEL DISCUSSION...TM
SOUTHCENTRAL ALASKA...ED
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CQ
MARINE/LONG TERM...RC

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE ANCHORAGE AK
951 PM AKST SAT MAR 5 2022

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

0806 PM     SNOW             13 SE KNIK              61.30N 149.53W
03/05/2022  M15.0 INCH       ANCHORAGE          AK   PUBLIC

0946 PM     SNOW             5 SW ANCHORAGE          61.15N 149.93W
03/05/2022  M12.8 INCH       ANCHORAGE          AK   PUBLIC

0740 PM     SNOW             5 SSE ANCHORAGE         61.15N 149.83W
03/05/2022  M12.3 INCH       ANCHORAGE          AK   NWS EMPLOYEE

            CORRECTS PREVIOUS SNOW REPORT FROM 5 SSE
            ANCHORAGE.

0610 PM     SNOW             6 SE ANCHORAGE          61.14N 149.82W
03/05/2022  M11.0 INCH       ANCHORAGE          AK   PUBLIC

0639 PM     SNOW             11 SE KNIK              61.32N 149.55W
03/05/2022  M10.5 INCH       ANCHORAGE          AK   PUBLIC

0601 PM     SNOW             12 SE KNIK              61.31N 149.54W
03/05/2022  E10.2 INCH       ANCHORAGE          AK   PUBLIC

0300 PM     SNOW             5 SW ANCHORAGE          61.16N 149.98W
03/05/2022  M9.9 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            TOTAL MEASURED SINCE THE START OF THE EVENT.

0839 PM     SNOW             8 SSE ANCHORAGE         61.10N 149.82W
03/05/2022  M9.5 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            SNOW IS TAPERING OFF.

0224 PM     SNOW             2 SW ANCHORAGE          61.20N 149.94W
03/05/2022  E9.0 INCH        ANCHORAGE          AK   PUBLIC

            ESTIMATED SNOWFALL RATE OF 1 INCH PER HOUR.

0730 PM     SNOW             BIG LAKE                61.51N 149.95W
03/05/2022  M9.0 INCH        MATANUSKA-SUSITNA  AK   NWS EMPLOYEE

0906 PM     SNOW             9 SE ANCHORAGE          61.12N 149.72W
03/05/2022  M9.0 INCH        ANCHORAGE          AK   PUBLIC

0230 PM     SNOW             2 NE ANCHORAGE          61.24N 149.85W
03/05/2022  M8.8 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            MEASURED 4.4 INCHES AT 10:30 AM.

0502 PM     SNOW             5 E ANCHORAGE           61.19N 149.76W
03/05/2022  M8.5 INCH        ANCHORAGE          AK   PUBLIC

0249 PM     SNOW             13 SE KNIK              61.30N 149.53W
03/05/2022  M8.0 INCH        ANCHORAGE          AK   PUBLIC

0916 PM     SNOW             11 SE ANCHORAGE         61.07N 149.77W
03/05/2022  M8.0 INCH        ANCHORAGE          AK   PUBLIC

0459 PM     SNOW             8 SSE ANCHORAGE         61.10N 149.82W
03/05/2022  M7.1 INCH        ANCHORAGE          AK   NWS EMPLOYEE

0200 PM     SNOW             3 E ANCHORAGE           61.21N 149.81W
03/05/2022  E7.0 INCH        ANCHORAGE          AK   PUBLIC

0230 PM     SNOW             5 SE ANCHORAGE          61.16N 149.80W
03/05/2022  E7.0 INCH        ANCHORAGE          AK   PUBLIC

0329 PM     SNOW             9 SSE ANCHORAGE         61.10N 149.74W
03/05/2022  M7.0 INCH        ANCHORAGE          AK   PUBLIC

            850 FEET ELEVATION.

0414 PM     SNOW             9 SE ANCHORAGE          61.12N 149.72W
03/05/2022  M7.0 INCH        ANCHORAGE          AK   PUBLIC

0458 PM     SNOW             8 SSE ANCHORAGE         61.10N 149.82W
03/05/2022  M7.0 INCH        ANCHORAGE          AK   PUBLIC

1128 AM     SNOW             1 E ANCHORAGE           61.21N 149.86W
03/05/2022  M6.8 INCH        ANCHORAGE          AK   PUBLIC

1009 AM     SNOW             2 S ANCHORAGE           61.19N 149.89W
03/05/2022  E6.0 INCH        ANCHORAGE          AK   PUBLIC

            4 INCHES FROM 7:30 TO 9:30 AM, 2 INCHES FROM
            9:30 TO 10 AM.

0230 PM     SNOW             BIG LAKE                61.52N 149.95W
03/05/2022  M6.0 INCH        MATANUSKA-SUSITNA  AK   NWS EMPLOYEE

            HEAVY SNOW STILL FALLING.

0319 PM     SNOW             6 SSW ANCHORAGE         61.14N 149.97W
03/05/2022  E6.0 INCH        ANCHORAGE          AK   PUBLIC

0400 PM     SNOW             5 WSW WASILLA           61.54N 149.60W
03/05/2022  M5.5 INCH        MATANUSKA-SUSITNA  AK   NWS EMPLOYEE

1005 AM     SNOW             5 SSW ANCHORAGE         61.14N 149.94W
03/05/2022  E5.0 INCH        ANCHORAGE          AK   PUBLIC

1029 AM     SNOW             3 E ANCHORAGE           61.21N 149.79W
03/05/2022  E5.0 INCH        ANCHORAGE          AK   PUBLIC

1252 PM     SNOW             4 W STERLING            60.51N 150.91W
03/05/2022  E5.0 INCH        KENAI PENINSULA    AK   PUBLIC

0400 PM     SNOW             4 NE KNIK               61.50N 149.67W
03/05/2022  E5.0 INCH        MATANUSKA-SUSITNA  AK   NWS EMPLOYEE

1225 PM     SNOW             5 SE ANCHORAGE          61.15N 149.82W
03/05/2022  M4.6 INCH        ANCHORAGE          AK   PUBLIC

0320 PM     SNOW             12 NNW HOPE             61.06N 149.76W
03/05/2022  M4.5 INCH        ANCHORAGE          AK   TRAINED SPOTTER

            24-HR SNOWFALL TOTAL.

0117 PM     SNOW             7 S ANCHORAGE           61.12N 149.86W
03/05/2022  M4.4 INCH        ANCHORAGE          AK   PUBLIC

1154 AM     SNOW             4 E ANCHORAGE           61.21N 149.78W
03/05/2022  M4.0 INCH        ANCHORAGE          AK   NWS EMPLOYEE

0430 PM     SNOW             3 ENE MEADOW LAKES      61.64N 149.51W
03/05/2022  M3.5 INCH        MATANUSKA-SUSITNA  AK   NWS EMPLOYEE

0116 PM     SNOW             10 E KNIK               61.42N 149.46W
03/05/2022  E3.0 INCH        ANCHORAGE          AK   PUBLIC

1136 AM     SNOW             9 SE ANCHORAGE          61.12N 149.72W
03/05/2022  M2.5 INCH        ANCHORAGE          AK   PUBLIC

1015 AM     SNOW             10 E KNIK               61.42N 149.46W
03/05/2022  E1.0 INCH        ANCHORAGE          AK   PUBLIC

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1018 PM AKST SAT MAR 5 2022

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

1003 PM     SNOW             6 SE ANCHORAGE          61.14N 149.82W
03/05/2022  M12.3 INCH       ANCHORAGE          AK   PUBLIC

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1047 PM AKST SAT MAR 5 2022

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

1040 PM     SNOW             VALDEZ                  61.13N 146.35W
03/05/2022  E24.0 INCH       VALDEZ-CORDOVA     AK   PUBLIC

&&

AP

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1242 AM AKST SUN MAR 6 2022

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

1230 AM     SNOW             1 NE ANCHORAGE          61.23N 149.86W
03/06/2022  M9.0 INCH        ANCHORAGE          AK   NWS EMPLOYEE

            1101 HOLLYWOOD DRIVE.

&&

NS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1243 AM AKST SUN MAR 6 2022

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

1104 PM     SNOW             13 SE KNIK              61.30N 149.53W
03/05/2022  M17.5 INCH       ANCHORAGE          AK   PUBLIC

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1244 AM AKST SUN MAR 6 2022

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

1107 PM     SNOW             15 E ANCHORAGE          61.23N 149.44W
03/05/2022  M15.2 INCH       ANCHORAGE          AK   PUBLIC

&&