Brisk Wind Advisory 81, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
533 AM AKDT Fri Apr 15 2022

.ANALYSIS AND UPPER LEVELS...

There is an upper level ridge spanning from Talkeetna to the Gulf
Of Alaska. On satellite imagery there is a mature low over the
eastern Bering with a frontal system pushing into Western Alaska
and over Kodiak. Advanced Scatterometer data (ASCAT) has detected
gale force winds with this low early this morning. Also on
satellite imagery (Nighttime Microphysics) there is an area of low
stratus/fog over Cook Inlet and portions of Prince William Sound.
The jet core is south of Dutch Harbor with a sliver of the jet
pushing across the AKPEN and Bristol Bay. On satellite imagery
(CIMSS MIMIC PW) there is a plume of modified tropical moisture
over the Eastern Bering that extends into the Northwest Pacific
Basin which is connected to former Typhoon Malakas. The radars at
Bethel and King Salmon have both detected light precipitation
overnight.

&&

.MODEL DISCUSSION...

Models consensus remains with the synoptic pattern for the next
48 hrs. By 12z Sunday there is divergence involving the low moving
south of the Gulf Of Alaska and the placement/timing of the
surface low as the extratropical remnants of Malakas move across
the Western and Central Aleutians. Regarding the Aleutians, the
ECMWF is the fastest, the Canadian is the slowest and the GFS/NAM
are in the middle of the pack. All of the models hold onto an H5
high over Prince William Sound which keeps it dry in the Anchorage
Bowl this weekend and into next week.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through
3...Friday through Sunday)...
A ridge of high pressure will try to keep weather quiet over the
mainland while a front brings more active weather to Kodiak and
parts of the Gulf. Mostly clear skies overnight have allowed for
another cold morning across most of the mainland. Across the
Gulf, widespread stratus has developed and will continue to flirt
with Cordova and Valdez this morning. As the front moves into
Kodiak, increasing cloud cover will spill over Cook Inlet. The
front is in association with a strong, broad low centered over the
Northern Bering. Precipitation continues to fall as rain over
Kodiak with temperatures near 40F. Rain will be steady there
through the day today into Sat. 1-1.5" of total QPF are expected
by Sat afternoon. The front is pushing up against the area of high
pressure, leading to an increased southeast gradient. This is
causing some breezy winds through the Turnagain Arm and gale-force
winds near the Barren Islands.

The ridge of high pressure will be strong enough to keep
conditions mostly dry for the interior portions of the mainland
through the weekend. However, there will be more passing high
clouds, which will limit the diurnal temperature swing just a bit.
A colder, arctic trough will sneak into the Copper River Basin
from the Yukon Territory late Sat-Sun. This could trigger some
convection along the mountains, especially Sat afternoon. The
colder air will not be anything too significant for Sunday, just
a gentle reminder that it is still April at 60N. Overnight lows
will continue to hover in the teens for Glennallen. Weak high
pressure will try to re-establish itself over the entire area by
late Sunday, finally bringing some drier weather to Kodiak.

&&

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

A ridge of high pressure continues to shift away from the
forecast area as a front extending from a Bering low continues to
move through the Southwest today. Gusty, southeasterly winds will
continue to increase in response to tightening pressure gradients
between the Mainland high and the Bering low. Winds funneling
through Kamishak gap will increase for the eastern corridor of
Bristol Bay, including Koliganek and New Stuyahok, before
subsiding this afternoon. Warm air ahead of the aforementioned
front has advected into the Southwest and will continue to track
northward as colder air is being advected in behind the front/low.
As a result, precipitation type for the Alaska Peninsula and
Southwest regions will predominately be rain with some mix of snow
as the atmospheric column of air warms above the surface.
Temperature highs will be in the upper 30s to low 40s on today.
However, higher elevations will see snow as colder air aloft stays
in place. Due to southeasterly flow, moisture associated with
these systems will be mostly limited to upslope favored areas on
the Kuskokwim and Aleutian Mountains. Most regions will stay
relatively dry due to downsloping through the weekend with the
exception of some moisture lingering for the Bristol Bay coast and
Alaska Peninsula.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS/ALASKA PENINSULA (Days
1 and 3: Tonight through Sunday afternoon)...

A negatively-tilted trough in the North Pacific will dominate the
forecast area over the next couple of days. Due to a deep Bering
low located in the base of the aforementioned trough, a swath of
gales with storm force gusts will cover most of the Aleutians with
high end small crafts elsewhere through Saturday. As the
aforementioned low continues to track across the Bering with its
associated front extending across the Southwest, a transition to a
rain/snow mix over the Chain will likely persist beginning today
and lasting through the weekend, as colder air wraps around the
backside of the aforementioned low. As the low weakens, a
secondary low from the extra-tropical remnants of Typhoon Malakas
will approach near Shemya Island on Sunday which will reinforce
another round of strong winds and a rain/snow mix through early
next week.

&&
.MARINE (Days 3 through 5)...

Gulf of Alaska: Expect winds less than 35 kts and seas less than 20 ft for the
Day 3 through 5 period.

Bering Sea: A North Pacific low is currently on track to approach
the southwestern Bering and western Aleutians by Sunday morning,
spreading easterly winds between small craft and gale force into
the far southern Bering. Gale force winds over the southern
Bering and along the Aleutians will shift east with the low
through Monday, becoming northerly near the Aleutians on the back
side of the low. Seas will build over the southern Bering to 12 to
17 ft through Monday, with Pacific side seas building as high as
25 ft. North to northwest gales near the eastern Aleutians will
slowly diminish Tuesday as the low exits, with seas subsiding to
around 10 ft Bering side and 15 ft Pacific side.

&&

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

A closed, blocking high sitting over northern Alaska is on track to
very slowly erode during the first half of next week as easterly
flow continues to support cool and dry conditions across
Southcentral and most of Southwest through at least Tuesday.
Meanwhile, leftover/extratropical circulation from Typhoon
Malakas will move southeast from the Eastern Aleutians back into
open waters south of the Gulf by Tuesday morning. Gusty winds and
areas of rain and snow across the Aleutians, Pribilofs and
southern Alaska Peninsula near this system on Monday should
diminish through Tuesday as the low pulls away and transient
ridging moves over the Aleutians.

Clarity from this point really begins to fall apart for the middle
to latter half of the week, owing mainly to differences in how
quickly the mainland blocking pattern breaks down and major
differences between models with the handling of the upstream
pattern across the far northwest Pacific. While uncertainty for
details remains high, there is still decent agreement for a
progressive pattern to continue into Wednesday/Thursday across the
Bering and Aleutians. Another deep low is likely to progress
across the Bering from the west, initiating another round of
strong winds and rain across the Aleutian Chain between Wednesday
and Thursday. Looking back east for this timeframe, a weak
easterly upper wave/low will most likely transit from the AK
Panhandle into Southcentral. This wave could help spur isolated to
scattered afternoon shower activity across Southcentral both
Wednesday and Thursday, mainly over valleys where solar heating of
snow-free patches is able to generate modest low level
instability.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale 173 174 175 176 177 180 181 185 411 412 413 414.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...PJS
SOUTHCENTRAL ALASKA...MO
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...NS
MARINE/LONG TERM...AS