Gale Warning 724, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
453 PM AKST Sun Nov 13 2022

.ANALYSIS AND UPPER LEVELS...

High pressure over the western Bering is bringing cold air south
towards the Aleutians with a cold front moving south near the
Aleutian Islands. An upper level trough is slowly moving across
western Alaska bringing in much colder temperatures. South of the
Aleutians a low pressure system is producing showers and
thunderstorms but this system will stay well south of the
Aleutians and AKPen. Across Bristol Bay a weakening surface low
continues to bring light rain and snow across Southwest Alaska
with only minor accumulations of snow across the area. Gusty
northerly winds continue to blow across the Kuskokwim Delta up to
35 knots. Light snow has been reported at Bethel, Aniak, and
Sleetmute. With rain and snow reported across the Bristol Bay area
with the radar showing areas of precipitation across the area. To
the east a deep southerly push of warm and moist air continues to
push north into Prince William Sound and eastern Kenai Peninsula.
A shortwave near Kodiak Island is supporting a surface low just
to the west of Kodiak City as it quickly moves north. Radar is
showing a swath of rain and snow from the Kenai Peninsula
extending north into the MATSU valleys with moderate to heavy rain
across Prince William Sound. Temperatures across Southcentral
have been in the upper 30s to low 40s from the MAT valley
southward, while low to mid 30s have been reported across the
Susitna valley as well as the Copper River Basin.

&&

.MODEL DISCUSSION...

Models continue to disagree slightly with the timing of the
surface low moving out of the western Gulf into the Anchorage and
MATSU valleys by this evening. Otherwise models agree well with
the high pressure over the Bering and high pressure building into
Southcentral by Tuesday. The biggest challenges will be timing
the onset of the gusty southerly winds later today across
Southcentral. And precipitation types tonight and tomorrow mainly
across the MATSU valleys as cold air slowly moves into the area
from the west as an upper level shortwave moves from western
Alaska towards Southcentral late Monday into Tuesday.

&&

.AVIATION...

PANC...A short period of MVFR ceilings are expected this evening
as a low pressure system brings rain across the area. Northerly
winds are expected through this afternoon ahead of this low. The
low is then expected to pass over the terminal as it moves north,
which will bring a period of strong southerly winds. During a
short period of time just after the low passes overhead gusts in
the 30 to 35kt range are possible. There is some uncertainty in
the wind forecast in regards to timing and strength, particularly
between 2Z and 6Z as the low moves through. After the low passes
winds will remain southerly while slowly diminishing tomorrow.

&&

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

A North Pacific low is slowly moving north of Cook Inlet this
evening with another round of precipitation and wind across
Southcentral. A potent upper level shortwave ahead of the moist,
southerly flow is aiding moderate to heavy rain showers along
Prince William Sound (PWS), especially over Valdez and Cordova. As
the low moves inland tonight, precipitation increases for the
rest of the forecast area. Models have generally trended a little
deeper with this system, so gusty south-southeasterly winds along
PWS and Turnagain Arm will likely continue before subsiding Monday
morning.

Meanwhile, a surge of warmer air, dynamic support, and lack of
downsloping will provide better chances of rain for the Anchorage
Bowl and Mat Valley heading into tonight. The northern Susitna
Valley could see snow accumulation up to 4 inches, but warmer
temperatures and gusty winds should keep the lower elevations a
predominate rain event. Precipitation overall is expected to taper
off during the morning hours on Monday as the main dynamics
starts shifting east and drier air filters in. The exception will
be for the Susitna Valley and PWS as south-southwest flow and
weak shortwaves will be in place until Monday afternoon.

A ridge of high pressure builds across the mainland state by
midweek with quieter weather, offshore flow, and colder
temperatures returning Monday night and Tuesday. Given a moist
boundary layer and warmer temperatures, the potential for fog
development will be the main concern for the week ahead. Over the
Gulf of Alaska, a broad low pressure system will push some rain
and wind northward into portions of the Eastern Kenai Peninsula
and Kodiak Island between Tuesday and Wednesday.

&&

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

Precipitation will start to come to an end late tonight and into
Monday as a surface low near Bristol Bay dissipates. A ridge of
high pressure will then move into the region and promote clearer,
dryer, and even warmer temperatures later in the week as
southerly flow takes hold. By Tuesday night into Wednesday,
precipitation chances will increase again for the region beginning
with the Alaska Peninsula and then working its way northward into
the Bristol Bay region for Wednesday as a North Pacific low
tracks towards the Alaska Peninsula and eastern Aleutians.
Temperatures will still be cooler through Tuesday, but by
Wednesday, southerly flow will influence temperatures across the
region to be in the upper 30s to low 40s.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3:
Tonight through Wednesday)...

A longwave ridge of high pressure is positioned over much of the
Bering Sea and western Aleutians with a persistent weak trough of
low pressure remaining offshore of Bristol Bay. A patch of
northeasterly small craft and gale force winds continue to stretch
over the YK Delta, across Nunivak Island, and into the Pribilof
Islands through tonight before slowly diminishing by late Monday
evening. The aforementioned ridge will continue to track across
the Bering before finally stretching to the Southwest coast
Tuesday. Upstream of the ridge, a strong upper-level low will
track into the western Bering early Monday. Expect high end gale
force winds and storm force winds west of Saint Matthew Island
through Wednesday along with elevated seas of 20+ feet from the
Western Aleutians, northward.

&&

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

A stagnant high pressure ridge will blanket much of the Alaska
Mainland through the long term, promoting generally benign
conditions across Southcentral through Sunday. As a result of deep
southerly flow with the ridge, above average daytime high and
overnight lows are advertised for both Southcentral and Southwest
Alaska through the weekend. Upper-level shortwaves within the
upstream ridge flow will track across Southwest Alaska and
maintain periods of precipitation through Saturday morning. Also
on Saturday, an upper-level low and attendant surface low are
expected to move into the Gulf of Alaska. At this time,
precipitation and winds accompanying the low look to stay
confined to the Gulf waters through Sunday.

Farther west, an upper-level trough is located over the Bering on
Thursday. There is decent agreement that the feature will lift
northeast towards the Bering Strait by Friday morning.
Precipitation will subsequently clear across the Bering with the
exit of the trough and the development of a shortwave ridge. Any
respite from precipitation across the sea will likely be short
lived; a front extending from a North Pacific low is expected to
reach the Western Aleutians already on Friday morning and
generally track into the Bering through the weekend. The exact
track and strength of the low has yet to be ironed out, however
rain and winds up to gale force are currently advertised to
accompany the low. The most recent GFS solutions show the low to
be slower and slightly stronger than the Canadian solutions.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale 119 150 177 178 180.
		 Storm 185.
FIRE WEATHER...NONE.

&&

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