Small Craft Advisory 178, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
355 AM AKST Fri Feb 21 2020

.ANALYSIS AND UPPER LEVELS...

An upper level low is currently centered over Siberia. Its
negatively titled trough extends through the eastern Bering and
south of the Alaska Peninsula near Kodiak Island. Persistent
north-northwesterly surface flow is indicated from the central
Bering/Aleutians westward. As such, blizzard conditions are now
observed over the Kuskokwim Delta near the coast. Winds will
gradually diminish through the morning.

A ~978 mb low is centered near Prince William Sound is bringing
coastal rain showers and inland snow showers to areas east of its
center in onshore southerly flow. A series of upper level
shortwaves is leading to light snow occurring across the western
Kenai Peninsula. This will gradually track northward into
Anchorage this morning.

&&

.MODEL DISCUSSION...

The large scale pattern is well-agreed upon. Several embedded
weak shortwaves will track across the northern Gulf over the next
few days however these should be fairly low-impact. Confidence is
average.

&&

.AVIATION...

PANC...Patchy fog will linger through sunrise with intermittent
LIFR ceilings. Light snow will develop by late-morning. Ceilings
and/or visibilities will likely persist at IFR through this
evening, before improving to MVFR thereafter as the snow
dissipates. Light winds will persist.

&&

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

The surface low south of Seward will move inland towards that
area, and continue to weaken through the evening as it heads
towards Turnagain Arm while washing out. Meanwhile, a swinging
trough will move into the Cook Inlet tonight from the eastern
Bering, with additional disturbances in the flow crossing the
region. Both of these features will continue to foster fairly
widespread precipitation across all of Southcentral, moving from
south to north through the day.

As far as precipitation/snowfall totals, the overall forecast
remains on track with the highest totals being 4 to 6 inches for
the western Susitna Valley, decreasing into the 2 to 4 inch range
for the Matanuska Valley, Anchorage Bowl, and Kenai Peninsula,
with similar amounts expected near the gulf Coast. Farther east,
look for a general 1 to 3 inches for the Copper Basin, with the
exception being Thompson Pass where around 5 or 6 inches should
accumulate.

Precipitation chances will diminish somewhat on Saturday, but a
closed mid-level low developing near Anchorage with additional
disturbances moving through will keep a chance of snow continuing.
A drier offshore flow will develop later Saturday night into
Sunday.

&&

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

An upper level low has helped keep blizzard conditions across the
Kuskokwim Delta Coast overnight and into this morning with areas
from Hooper Bay and Kipnuk seeing multiple hours of winds above 35
mph and visibility of a quarter mile. These conditions will
continue this morning before improving by this afternoon as the
upper level low lifts north, causing winds and snowfall to taper
off. Lingering snow showers across the remainder of Southwest
mainland will diminish overnight tonight into Saturday morning as
high pressure begins to move in. This weekend will see calmer
winds, colder temperatures and sunny conditions. Overnight
temperatures tonight will drop below zero, then drop even lower
into the teens to twenties below zero on Saturday night across
most of interior Southwest as clear conditions continue.

&&

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

Cold, Arctic air continues to move in across the Bering Sea
associated with the low over the northern Gulf. This will keep
widespread snow showers for the Bering through much of the day
today through Saturday. Strong winds will also persist across the
eastern Aleutians and AKPEN, with the potential for some blowing
snow early this morning, before winds diminish overnight with the
weakening low.

As weather becomes calm over the eastern Bering, the next strong
low system approaches the western Aleutians Saturday morning.
This feature will continue its path eastward, skimming the central
Aleutians with an area of gale-force winds and precipitation,
through Sunday.

&&

.MARINE (Days 3 through 5 Sun through Tue)...

A low south of the central Aleutians Sunday morning will move
eastward across the eastern Aleutians Sunday and into the Gulf on
Monday. Gale force winds are expected with this low. Gale force
northerly winds are possible in the central and Western Aleutians
Monday night and Tuesday. Confidence in the forecast for Monday
night and Tuesday is fairly low.

&&

.LONG TERM FORECAST (Days 4 through 7 Mon through Thu)...

On Monday morning the pattern will consist of an upper level
trough over the Copper River basin extending south into the
northeast Gulf of Alaska, an upper level ridge over southwest
Alaska extending into the eastern and central Bering Sea, and
upper level lows south of the eastern Aleutians and south of the
western Aleutians. The trough over the Copper River basin will
slowly slide east into Canada by Monday afternoon. The ridge will
move east and north through Tuesday. The ridge will then split,
with one half moving into Canada and the other half retreating
westward into northeast Russia. The eastern Aleutian low will
move east and a bit north through Wednesday, undercutting the
ridge over southern Alaska and settling in the Gulf Wednesday into
Thursday. The western Aleutian low has a more uncertain future,
possibly staying nearly in place or it could move into the Bering.
Model spread is fairly large for the extended portion of the
forecast and confidence is fairly low.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Blizzard Warning: 155.
MARINE...Gale Warning: 130 131 176-178.
 Heavy Freezing Spray Warning: 130 138 139 150 160 165 179 180 185
FIRE WEATHER...NONE.

&&

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
251 PM AKST FRI FEB 21 2020

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

1200 AM     BLIZZARD         HOOPER BAY AIRPORT      61.52N 166.13W
02/21/2020                   KUSILVAK           AK   ASOS

            HOOPER BAY AIRPORT ASOS REPORTED BLIZZARD
            CONDITIONS FROM 9:40AM AKST ON THE 20TH
            THROUGH 7:56AM AKST ON THE 21ST.

&&

ED

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
254 PM AKST FRI FEB 21 2020

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

0700 PM     BLIZZARD         TOKSOOK BAY AIRPORT     60.53N 165.12W
02/20/2020                   BETHEL             AK   ASOS

            TOKSOOK BAY AIRPORT ASOS REPORTED BLIZZARD
            CONDITIONS FROM 7:32AM AKST ON THE 20TH
            THROUGH 12:56AM AKST ON THE 21ST.

&&

ED

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
256 PM AKST FRI FEB 21 2020

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

1200 PM     BLIZZARD         CHEVAK AIRPORT          61.54N 165.60W
02/20/2020                   KUSILVAK           AK   ASOS

            CHEVAK AIRPORT ASOS REPORTED BLIZZARD
            CONDITIONS FROM 6:33AM AKST ON THE 20TH
            THROUGH 4:56PM AKST ON THE 20TH.

&&

ED

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE ANCHORAGE AK
314 PM AKST FRI FEB 21 2020

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

0255 PM     SNOW             1 NNW HOMER             59.65N 151.53W
02/21/2020  E4.0 INCH        KENAI PENINSULA    AK   LAW ENFORCEMENT

0230 PM     SNOW             1 NW SOLDOTNA           60.50N 151.10W
02/21/2020  E4.0 INCH        KENAI PENINSULA    AK   PUBLIC

            NEAR SOLDOTNA.

0130 PM     SNOW             1 NW SOLDOTNA           60.50N 151.10W
02/21/2020  M2.0 INCH        KENAI PENINSULA    AK   PUBLIC

0100 PM     HEAVY SNOW       17.5 MILES OUT EAST END 59.78N 151.17W
02/21/2020  M12.0 INCH       KENAI PENINSULA    AK   FIRE DEPT/RESCUE

            8-12 INCHES NEW SNOW WITH BLOWING SNOW.

&&