Small Craft Advisory 869, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
510 AM AKDT Wed Nov 2 2022

.ANALYSIS AND UPPER LEVELS...

A deep upper level low is situated over Southwest Alaska tracks
eastward across the Mainland. The associated front moved into the
southern Gulf of Alaska during the overnight hours and a triple
point low is developing within the trough, near the southern end
of Shelikof Strait. There is some model inconsistency with this
low, but the overall track shows movement towards Prince William
Sound by tonight. Additionally, shortwaves will move across
Southcentral today and Thursday. Again, some minor model
inconsistency, which could end up having some effect on winds
across Anchorage and the Hillside. Further west, upper level high
pressure moves into the western Bering this evening.

Model guidance is hinting at a weak surface low moving out of
Russia towards Southwest Alaska on Friday morning along with a
cold air mass and a quick shot of snow.

&&

.MODEL DISCUSSION...

Models are in fair synoptic agreement overall through the short
term. There remains inconsistencies regarding the shortwaves
passing over Southcentral, which could affect snowfall in some
areas, as well as a triple point low developing near northern Shelikof
Strait. The triple point low has been causing grief amongst the
models for a few days, which is pretty typical for these types of
systems. They have slowly been trying to come into agreement,
however, the GFS has been holding strong with its stance on
keeping the low largely over the Gulf of Alaska, while the
EC/Canadian track more north and inland over the Kenai Peninsula.
Additionally, the NAM is trending towards a dual low development
on either side of the Kenai Mountains. There is, however, a
general consensus that the low will track towards Prince William
Sound through tonight.

&&

.AVIATION...
PANC...Periods of wind shear likely through the morning. Periods
of snow expected to persist into tonight. Cloud ceilings will
stay around MVFR. Additionally, visibility will be marginal or
lower into the afternoon and evening hours.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 2: Today
through Thursday night)...

A strong low pressure system is tracking through the area today
with a 180 knot jet streak supporting a strong frontal system
currently moving north across the Gulf of Alaska and Kenai
Peninsula; this is bringing rain to coastal areas and snow
inland. A triple point low will form this morning near the
southern Kenai Peninsula and track along the eastern coast of the
Peninsula and towards Prince William Sound by this afternoon and
evening. There is still some minor model differences with the
positioning of the triple point low, but it is not expected to
significantly affect the overall forecast of snow and winds.
Strong winds ahead of the front with Gales across the Gulf and
strengthening winds this morning across Turnagain Arm and the
Anchorage Hillside. Expect sustained winds on the hillside of 30
to 40 mph with gusts of 50 to 60 mph this morning. The winds will
weaken by this afternoon as the front moves inland and the low
tracks north. Light snowfall is expected across the western Kenai
Peninsula, Anchorage and MAT valley with up to 3 inches expected
through tonight with up to 6 inches on the hillside. Heavier snow
is expected across the western Susitna valley through tonight
where a winter weather advisory is in effect until 10 PM with 8 to
12 inches expected. The heaviest snowfall will be along the
coastal mountains with up to 2 to 3 feet expected. Up to a foot of
snow is expected around Valdez with 6 to 10 inches expected
around Portage valley and Whittier areas. Seward will see wet snow
with possibly an inch this morning but temperatures are expected
to warm with rain expected by mid-day into the evening hours.
Tonight through Thursday morning a weakening upper level low will
track slowly across the area with light snow across the area with
1 to 2 inches of snow expected across valleys and near sea level.
Thursday afternoon and evening this low will open up into a
shortwave trough and track towards the Copper River Basin. Another
shortwave will dip south towards Southcentral by Thursday night
with light snow continuing across the Anchorage and MATSU valleys
with light accumulations of two inches or less expected. As the
surface low moves east across the Gulf on Thursday northwesterly
gap winds will ensue and increase Thursday night as cold air
advection filters across the region.

&&

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

An upper-level low located along the Kuskokwim Delta coast will
track inland to the Lower Kuskokwim Valley during the day today as
its attendant surface front approaches the western Alaska Range
this morning. Strong winds and heavier snowfall rates will
diminish through the morning hours and, thus, blowing snow
hazards are expected to remain below advisory criteria. However,
some areas may continue to experience lower visibility from
blowing snow well into the afternoon.

With the frontal passage across the Southwest coast, winds have
shifted westerly to southwesterly along the Bristol Bay coast.
Subsequently, a push of warm air has transitioned snow into rain
for many locations along the Bristol Bay coast. This is not
expected to limit total snow accumulations since the bulk of
precipitation has already moved inland with the front. These
strong westerly to southwesterly winds along the backside of the
low may lead to minor coastal flooding and erosion for this
coastal area. Thus, a Coastal Flood Advisory remains in effect
through mid-morning for the Bristol Bay coast from Jacksmith to
Togiak.

Conditions across Southwest will gradually clear later today
leading into Thursday as the system exits into Southcentral and
surface high pressure nudges in from the west. A northwesterly
flow regime will also set up for Thursday, which will allow more
cold air to advect across the domain and drop daytime temperatures
down near the 20s. By Friday, chances for snow return as a
surface low enters from the northwestern Bering. The exact timing
and placement of this low has yet to be ironed out, but it
currently looks to enter the Kuskokwim Delta on Friday morning and
then generally track southeast across the Kuskokwim Mountains for
the remainder of the day.

&&

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

Persistent northwesterly flow sets up across the domain for the
next several days as an upper-level low and attendant surface low
continue tracking east into Southwest Alaska. Precipitation and
strong westerly winds along the back and southern side of the low
(over the Eastern Bering) will taper off through the day today.
Chances for rain and snow showers linger across the Central
Bering through today as a result of a another weakening low
pressure system. High pressure enters the domain from the west on
Thursday, yielding generally calmer and drier conditions through
Friday. However, the Eastern Bering and Aleutians are expected to
experience gusty northwesterly winds in tandem with cold air
advection and snow showers for Thursday and Friday.

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

At the onset of the forecast period, the longwave pattern features
a positive tilt trough axis over the Gulf Of Alaska through to
the Northwest Territory, a high amplitude ridge axis over the
Central/Eastern Aleutians and another trough axis over eastern
Russia. It is a highly amplified pattern. At the surface on
Saturday, cyclonic flow continues over the Gulf Of Alaska, the
ridge axis has shifted to the eastern Bering and a frontal
boundary is now east of Kamchatka. By Sunday there is a tight
thermal gradient along the eastern Gulf of Alaska and wide area
of high pressure at the surface which spans from Nunivak to the
interior of Alaska.Also Sunday the models bring a surface low
towards Adak but the tracks are divergent. On Monday the global
models begins to struggle with the North Pacific and the southern
Bering. Cold temperatures will dominate the forecast period with
the most brutal temps expected in the Copper River Basin which
could see temperatures into the negative 20s to negative 30s,
which hinges on the presence of fog or low stratus.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory: 131 (Thompson Pass), 145, 155
		 Coastal Flood Advisory: 161
MARINE...Storm Warning: 130 131
	 	 Gale Warning: 119 120 125 132 136 138 150 160 165 180
					   351 352 414
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...KM
SOUTHCENTRAL ALASKA...RC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AF
LONG TERM...PJS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1103 AM AKDT WED NOV 2 2022

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

1053 AM     SNOW             2 N HOMER               59.66N 151.53W
11/02/2022  M2.5 INCH        KENAI PENINSULA    AK   PUBLIC

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1121 AM AKDT WED NOV 2 2022

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

1121 AM     SNOW             1 NE CLAM GULCH         60.24N 151.38W
11/02/2022  M20.0 INCH       KENAI PENINSULA    AK   DEPT OF HIGHWAYS

            12 INCHES OVERNIGHT, 8 INCHES NEW SNOW THIS
            MORNING.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
205 PM AKDT WED NOV 2 2022

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

0100 PM     SNOW             NIKISKI                 60.70N 151.30W
11/02/2022  M20.0 INCH       KENAI PENINSULA    AK   PUBLIC

            14 INCHES MEASURED AT 6:30AM, 20 INCHES
            MEASURED AT 1PM.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
215 PM AKDT WED NOV 2 2022

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

0213 PM     SNOW             2 SW KACHEMAK           59.65N 151.46W
11/02/2022  E0.0 INCH        KENAI PENINSULA    AK   OTHER FEDERAL

            TRACE/DUSTING OF SNOW IN HOMER.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
221 PM AKDT WED NOV 2 2022

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

0220 PM     SNOW             1 NW ANCHOR POINT       59.78N 151.83W
11/02/2022  M12.0 INCH       KENAI PENINSULA    AK   TRAINED SPOTTER

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
312 PM AKDT WED NOV 2 2022

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

0307 PM     SNOW             5 MILES NE OF FRITZ CRE 59.78N 151.17W
11/02/2022  M3.5 INCH        KENAI PENINSULA    AK   FIRE DEPT/RESCUE

            3 INCHES NEAR THE FIRE STATION AND 4 INCHES
            EAST TOWARDS FOX RIVER.

&&

CJ