Small Craft Advisory 877, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
435 AM AKDT Sat Nov 5 2022

.ANALYSIS AND UPPER LEVELS...

A broad arctic trough is draped over Mainland Alaska with
multiple lows embedded within it. Upstream of the aforementioned
trough is a ridge of high pressure situated over the central
Bering/Aleutians. Cold air continues to build into the Copper
River Basin from the northeast which will begin to push through
Thompson Pass, the Chickaloon Pass, and out of the Matanuska
River. Due to this push of cold air, strong gusty winds are
already being observed with gusts of 43 kts in the port of Valdez
and in the Matanuska Valley. These winds and gusts will continue
to increase even more throughout the day. As such, High Wind
Warnings for the Matanuska Valley and Northeast Prince William
Sound, including Valdez and Thompson Pass, have been issued.
Further west, a warm front is situated over the western Aleutians
and continues to push warmer temperatures to the central Bering
and will move toward Southwest Alaska later this weekend.

&&

.MODEL DISCUSSION...

Models remain in good overall synoptic agreement through the
weekend. Model spread grows slightly with the subtle features
such as the timing of weak upper-level waves and how they may
impact the gusty gap winds that will occur the next few days along
the Gulf coast as well as the Matanuska Valley. This will be the
main forecast challenge in the coming days until precipitation
type rears its head in Southwest Alaska early next week.

&&

.AVIATION...
PANC...VFR conditions will persist. Northerly winds will be gusty today
with gusts reaching 25 to 30 kt and then slowly decreasing for
Sunday morning.

&&

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

A strong pressure gradient along with cold air filtering down from
the north will keep strong gap winds going through Sunday morning.
A shortwave moving down from the Yukon along with an upper level
jet moving over the area will reinforce the cold air today and
allow winds to strengthen especially across the Matanuska Valley
and around the Valdez to the Thompson Pass area where high wind
warnings are in effect for these locations through Sunday morning
with gusts ranging from 60 to 80 mph. Otherwise Kodiak City,
Seward, and Whittier will also have winds gusting to 50 to 60 mph
through this evening. On Sunday a ridge moves across the area and
will allow the winds to relax and weaken through the day. By
Sunday night a frontal system will begin moving towards the
western Gulf and Kodiak Island with gusty easterly winds and rain
and snow. Stay tuned as we monitor this next frontal system.

&&

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

Dry conditions and clear skies today through a big chunk of Sunday
as an upper level ridge cross over Southwest Alaska. Late Sunday
evening, the leading front extending from a North Pacific low
moving into the southern Bering pushes onto the Southwest coast.
There is a warmer air mass just behind the front that pushes into
Southwest Monday afternoon. Northerly winds transition to
southeasterly and become gusty through the night Sunday into
Monday and will remain gusty through the early portions of next
week. A strong moisture feed will bring about heavy snow to
Bristol Bay late Sunday night/early Monday morning. Snow switches
to a rain/snow mix late Monday morning, quickly becoming all rain
as temperatures rapidly warm above freezing by Monday afternoon
along the Southwest coast. Snow is expected elsewhere across
Southwest Alaska beginning late Sunday night as well, but will be
considerably less intense. There is still some uncertainty
regarding snow amounts, particularly from Dillingham north to New
Stuyahok and west to Togiak, who may see ranges anywhere from 8 to
12 inches of new snow. The Alaska Peninsula and Kuskokwim Delta
is expecting 1 to 3 inches of new snow, and 2 to 5 inches is
possible in the lower Kuskokwim Valley. Additionally, while this
is going to be a heavy, wet snow, there is still potential for
some blowing snow that can cause visibility issues at times.
Forecast confidence remains low to moderate at this point for
whether blowing snow will reach advisory level due to heavy, wet
snow being less easily transportable. Finer details will continue
to be assessed along with new, updated model data.

&&

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

Upper level ridge slips off to the east today, pushing onto the
Southwest Mainland, ahead of an approaching North Pacific low. A
weakening front remains stationary over the western/northern
Bering Sea, producing widespread gale force winds through today.
The North Pacific low moves south of the Central Aleutians early,
early Sunday morning. The eastern edge carries areas of
southeasterly, storm force winds that will push across the Eastern
Aleutians Sunday morning, with high end gale force winds expected
along the southern Alaska Peninsula, including Cold Bay and King
Cove. Periods of storm force winds will persist through the gaps
and passes of the southern AKPen into Sunday night, diminishing by
early Monday morning. Additionally, heavy precipitation will
follow the associated front extending across the Central and
Eastern Aleutians, as well as up the Alaska Peninsula. Though mostly
rain is expected as a warmer air mass follows the front, there
will still be periods of snow or a rain/snow mix along the higher
elevations.

&&

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

General synoptic features and patterns are showing strong agreement
for Southern Alaska through the long-term period, with solutions
beginning to diverge more intensely by Friday morning. Tuesday
morning, a low moving eastward along the Aleutians will drive a
leading front up the Alaska Peninsula into Southcentral. A tighter
pressure gradient associated with this frontal boundary may give
rise to higher winds through the Barren Islands, into the Kenai
Peninsula, and Prince William Sound Tuesday afternoon and evening.
Currently, models advertise the aforementioned low to move
eastward from the Aleutians and into the Central Gulf by Wednesday
afternoon, keeping precipitation south of Southcentral Alaska.
This low however will still be providing an ample set-up for
stronger winds along coastal Southcentral. A ridge positioned
behind this low looks to do very little at halting the advancement
of a much stronger North Pacific low entering the western
Aleutians by Wednesday afternoon. Models often struggle on the
breakdown of these ridges and tend to break them down faster than
what occurs. That being said, models are converging on this solution
of a N Pac low coming into the Bering - which raises confidence.
Timing of this new low's entry into the Bering requires further
investigation. After entering the Bering models have very little
consensus on the behavior and track of the system.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...High Wind Warning: 111, 131.
MARINE...Storm Warning: 170-172, 127.
		 Gale Warning: 119-121, 125-126, 128-132, 136, 138, 150, 155,
					   165, 173-180, 185, 351-352, 411-414.
FIRE WEATHER...NONE.

&&

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
142 PM AKDT SAT NOV 5 2022

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

1253 PM     NON-TSTM WND GST PALMER                  61.60N 149.11W
11/05/2022  M53 MPH          MATANUSKA-SUSITNA  AK   ASOS

            PAAQ REPORTED 39 MPH GUSTING TO 53 MPH.

0115 PM     NON-TSTM WND GST VALDEZ                  61.13N 146.36W
11/05/2022  M66 MPH          CHUGACH            AK   ASOS

            PAVD REPORTED 25 MPH GUSTING TO 66 MPH.

&&