Gale Warning 197, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
540 PM AKST Wed Feb 23 2022

.ANALYSIS AND UPPER LEVELS...

The upper levels are dominated by a trough over the Bering Sea and
a ridge of high pressure over the Copper River Basin. The trough
has tried to hold cold air in place, but due to its extensive size
and its duration, it has allowed plenty of warm air to migrate up
its eastern periphery. Warm air has filtered into all of southern
AK with temperatures climbing into the mid 30s as far north as
Hooper Bay. While precipitation is not heavy or widespread for any
area, what is falling across SW is falling as rain early today.

Shifting to the east, the ridge of high pressure is transient and
already pushing into Canada. It created an environment ripe for
fog and low stratus across many of the population centers this
morning. Anchorage International dipped down to 1/4 mile
visibility at times. Now, a weak front is lifting from Kodiak
towards the Kenai Peninsula. This has helped to quickly disperse
nearly all the fog and stratus. It has brought very soggy
conditions to Kodiak with over a half inch of rain already
reported since midnight. Light returns are starting to show up
on radar spreading from Homer up towards Anchorage.

&&

.MODEL DISCUSSION...

The models remain in good overall agreement. This is leading to
moderate forecast confidence. The main issues revolve around the
low position (both upper level and surface) by Friday morning near
Bristol Bay. The 12z run of the NAM started a shift towards a
slower and further east solution. The subsequent model runs have
showed some support for this theory, with the exception of the
GFS. The GFS is holding course taking the low through the Alaska
Peninsula faster and keeping it further west. Regardless, none of
these solutions should have a big impact on the amount of QPF that
falls over the Eastern Kenai Peninsula and Prince William Sound.
The forecast challenge will surround the potential for Warning
level winds being able to develop in Turnagain Arm and into the
Anchorage Hillside.

&&

.AVIATION...
PANC...VFR conditions will persist. North winds will increase
through the TAF period. Some showers in the vicinity will be
possible by Thu afternoon.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3 -
Tonight through Saturday)...

Active weather has resumed for Southcentral as a surface front
and upper level waves embedded in the flow aloft spread
precipitation northeastward along the west Gulf Coast this
afternoon. The Turnagain Arm wind has also redeveloped as a result
of a strengthening east-to-west pressure gradient. These winds
are expected to persist well into Saturday morning and will be
the strongest on Friday.

Precipitation for this weekend will be focused along the eastern
Kenai Peninsula, western Prince William Sound, and southern parts
of the Alaska Peninsula. Much of the precipitation will fall as
rain at and near sea level, but snow can be expected at higher
elevations. Rain will intensify tonight into Thursday morning as
the next surface front and upper level waves push into Southcentral.
Precipitation will continue through the day on Thursday and then
re-intensify again Thursday night through Friday with the next
surface front and upper level waves pushing into the region. Rain
combined with melting snow may create areas of standing water on
roadways where poor drainage exists, particularly near Turnagain
Pass. Please see the associated Special Weather Statement for more
details. By Saturday morning, rain will start to taper off from
south to north along the coast as the system moves inland and
dissipates. Overall, Whittier is expected to see the highest rain
amounts of 6 to 10 inches from this event.

The western Kenai Peninsula and Anchorage Bowl are expected to
stay relatively dry through the weekend as a result of downsloping
from strong southeasterly winds. In summary, active weather will
persist through Saturday morning and then give way to slightly
calmer conditions by Saturday afternoon.

&&

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

Southeasterly flow will continue to dominate the area through
Saturday, with several shortwaves bringing rain to portions of
the area. Most of the rain will be along coastal areas while
west of the mountains downsloping will minimize precipitation.
Otherwise, expect snow in the mountains. Winds will also remain
gusty across the region through Friday and then begin to relax a
bit by Saturday as the pressure gradient weakens. Friday into
Saturday a cold front will bring in slightly cooler air with
chances of snow across the area, with only minor accumulations
and no significant impacts.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3 -
Tonight through Saturday)...

A low pressure system will move northwest across the Bering Sea
with a front extending across the eastern Bering through tonight.
This system will bring Gales to the northern and eastern Bering.
As this system moves out of the area tonight winds will decrease
to small crafts or less across much of the area on Thursday.
Another low will approach the AKPen Thursday night bringing a
round of Gales south of the AKPen and across the eastern Bering.
This low will track along the Southwest Alaska coast and towards
the northern Bering by Friday night and Saturday with the winds
decreasing to small crafts by Saturday near the low. However,
there are model differences on how fast this low tracks northwest
with the GFS the fastest solution and the outlier at this point.

&&

Gulf of Alaska:
A front extending across the Northern Gulf moves onshore for late
Saturday. High pressure moves across the Gulf through Monday.
Forecast confidence is moderate. A high end gale force barrier jet
along the North Gulf Coast diminishes late Saturday. Seas to 20
feet, subsiding. A new front approaches the Western Gulf for Monday.

Bering Sea/Aleutians:
A well developed Central Bering low moves into the Russian Far
East for Sunday. A developing North Pacific low and front pushes
across the Western Bering by Monday. Forecast confidence is
moderate. Gusty winds surround the Central Bering low, with areas
of Southerly gales along the Eastern flank, diminishing Sunday.
Seas less than 10 feet. The Pacific low and front brings Southerly
gales, with areas of storm force winds over the Western Aleutians
and Bering. Seas build to 16 feet along the Pacific side of the
Western Aleutians by Monday.

&&

.Long Term Discussion (Days 4 through 7: Sunday through
Wednesday)...

The longwave pattern will feature a broad trough over the Bering
Sea and much of Mainland Alaska. For the Bering, the negative
height anomalies at 500 mb persist through March 3rd. However the
situation is a little more complicated for the Mainland at 500 mb
as they transition from negative to positive. The Bering and the
North Pacific will be major areas of cyclogenesis this forecast
period. The models spin up a number of lows at the surface,
however there is some divergence regarding the tracks of the
surface lows and the intensities. However, all the models are
forecasting a busy period for the Northwest Pacific and the
Bering Sea. And some of this activity will move into the Gulf Of
Alaska. The predominately dry areas with the possibility of
intermittent light showers for this time frame will be Talkeetna
to Anchorage. High temperatures for the Anchorage Bowl and Mat-Su
Valleys will be slightly above freezing ranging from 33F-39F.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Storm Warning 119 130 139
       Gale Warning 120 125 131 132 137 138 140 141 150 160 185.
FIRE WEATHER...None.

&&

SYNOPSIS AND MODEL DISCUSSION...MO
SOUTHCENTRAL ALASKA...AF
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...RC
MARINE/LONG TERM...PS