Brisk Wind Advisory 69, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
525 PM AKDT Thu Mar 24 2022

.ANALYSIS AND UPPER LEVELS...

A large and deep occluded low over the southern Gulf of Alaska
is tracking slowly northwestward toward Kodiak Island. A leading
upper level short-wave is crossing from Kodiak Island into Bristol
Bay, with snow spreading westward. While the snow intensity is
generally light, there is a narrow band of deformation and heavier
snowfall. Meanwhile, satellite imagery indicates a jet streak
with deep synoptic scale lift and moisture transport from the
southeastern Gulf to the Kenai Peninsula. Moderate to heavy
precipitation is streaming right toward the eastern Kenai Peninsula.
Strong low level east to southeast flow is enhancing precipitation
rates across western Prince William Sound/Eastern Kenai Peninsula.
Marginally warmer air is also advecting into the region, leading
to rain or a rain/snow mix near sea level along the Gulf coast
and eastern Kenai Peninsula. Snow levels have risen to about
500 ft or higher. Thus, higher elevations of the Seward Highway
corridor along with bordering mountains are observing reduced
visibilities in accumulating snow. The strong easterly flow is
leading to drier conditions west of the Kenai and Chugach
Mountains, though atmospheric instability (as seen in the 12Z
Anchorage sounding) is producing some spillover precipitation.

Out west, conditions are much quieter across the Bering Sea and
Aleutians, with just some scattered showers. There are some gusty
northwest winds across the eastern Bering, eastern Aleutians, and
southern Alaska Peninsula in between the Gulf low and a ridge over
the western Aleutians. An intensifying low along the subtropical
jet in the North Pacific is tracking northeastward toward the
Aleutian Chain.

&&

.MODEL DISCUSSION...

Overall, models remain in decent agreement with large scale
features over the next few days. As has been the case for numerous
model runs, the GFS continues to be an outlier over the northern
Gulf Tonight through Friday morning as it tracks a surface low
and upper level short-wave around the north side of the main Gulf
low, resulting in a stronger wind field. Will continue to favor
the rest of the guidance with a much weaker wave and little impact
on the already strong easterly winds across the northern Gulf
coastal waters. Meanwhile, models continue to trend northward with
track of a deep low along the Aleutians Friday night through
Saturday, so the forecast will reflect that trend.

&&

.AVIATION...

PANC...The combination of an upper level short-wave and weak
atmospheric stability will allow some precipitation to make it
over the Chugach Mountains late this afternoon through this
evening. While precipitation will be heavier and longer lived
right along the mountains, do expect a brief period of snow at
the terminal. It's hard to nail down the exact timing, the core
time seems to be centered from 03Z to 06Z. Would expect similar
ceiling/vis to what occurred Wednesday night, with high end IFR
to MVFR in the snow showers. Other than the short period of snow,
expect VFR conditions to prevail.

&&

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

An occluded front over the Gulf will continue to bring rain/snow
mixed and higher gusts across the eastern Kenai Peninsula to
parts of Anchorage Bowl through Prince William Sound tonight. This
unsettled pattern will continue through at least Fri night as the
next North Pacific low enters the Gulf late tonight into Fri
morning. This latter system will send a couple of upper-level
short waves across the northern Gulf including Kenai Peninsula and
the Anchorage Bowl through Fri night. Weather observations
indicated easterly winds and warm temperatures in the upper 30s
to lower 40s across Prince William Sound while gentle to moderate
northeasterlies extends farther inland including Anchorage this
afternoon.

At Kodiak Island, northerly winds will persist there through
Friday. A weakening low east of Kodiak is still aiming toward
Kodiak Island this evening, followed by the next North Pacific
low late tonight into Fri morning. Winds along the western Kenai
Peninsula will reach up to 20 to 25 mph with mainly gale force
winds over the Cook Inlet and Shelikof Strait tonight.

&&

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

Northerly flow over through Bristol Bay area and the AKPen with a
trough near the western Gulf is bringing areas of snow through
King Salmon and Dillingham this afternoon. Weather in Bethel is
expected to remain fairly quiet with high overcast clouds.
Precipitation will begin to diminish overnight but should remain
cold enough for the slight chance of snow to linger through the
weekend. One to two inches of snow is expected into Friday morning
with high amounts in the mountains and for Pilot Point and Port
Heiden. Increased winds through the gaps along the AKPen could
accelerate to gale force tonight through Friday. Another low with
its center near the Aleutians Islands will continue to move east
and will arrive to the AKPen by the end of the weekend. The low
appears to move south enough that the northward extent may keep
chances for precipitation lower.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through
3...Today through Sunday)...

A brief ridge of high pressure over the central Aleutians
tonight. Clouds will fill in as a low moves northeast towards the
western and central Aleutians tonight into Saturday morning. The
low is expecting to nudge a little more north than previous model
runs which will allow precipitation to spill into the southern
Bering but should remain south of the Pribilofs. Gales are
possible near the low and could affect locations along the central
islands Saturday morning. Overall, temperatures will remain cool
enough for precipitation to begin as snow or a mix rain and snow.
The low center will pull just enough warm air north that
precipitation closer to the low center on Saturday will turn to
rain before switching back to a mix and then over to snow Sunday.
The passage of this low will help enhance northerly flow across
the Bering Sea on Sunday. A low near South Kamchatka will begin to
reach the western Aleutian extent Sunday night.

&&

.Marine (Days 3 through 5: Sunday through Tuesday)...

Gulf of Alaska: A front entering the Southwest Gulf extends
across the Gulf through Tuesday. Forecast confidence decreases
through Tuesday. Gusty East to Southeast winds increase to high
end gales as the front moves across the Gulf through Tuesday.
Areas of storm force barrier jet winds are likely late Monday.
Seas build to 14 feet over the Southern Gulf for Tuesday.

Bering Sea: A strong low tracks Eastward to the South of the
Aleutians and Alaska Peninsula through Tuesday. high pressure
moves into the Northeast Bering for Tuesday. A well developed
front pushes into the Western Bering by Tuesday. Forecast
confidence is Fair. Gusty Northerly winds increase to gales over
the Eastern Aleutian and Alaska Peninsula for Tuesday. Seas to 12
feet, subsiding. Freezing spray over parts of the Southern Bering
on Sunday. High end Southerly gales with the Western Bering front
become Southeasterly for Tuesday. Areas of storm force winds with
the front on Monday. Seas build to 20 feet Tuesday.

&&

.Long Term Discussion (Days 4 through 7: Monday through Thursday)...

The pattern remains amplified as an upper trough moves across
Southcentral Monday through Wednesday. Weak transient upper level
ridging will then build over Southcentral on Thursday. As the
West Pacific Oscillation strengthens in the positive phase, upper
level troughing will gradually deepen across the Bering/Aleutians.
This pattern will be more conducive to cloudy and wet conditions
across Southcentral due to broad onshore geostrophic flow.

A slow moving low pressure system will move northeastward through
the Gulf of Alaska Monday through Wednesday night. This low will
bring precipitation to the area. Confidence is low with respect to
precipitation type, though the greater chance for snow will be in
the mountains and across cooler inland areas while rain is more
likely in lower coastal locations. Strong Turnagain Arm winds are
possible on Monday due to the onshore geostrophic flow that is
associated with the aforementioned low. These winds are unlikely
to bend into Anchorage due to the strong down-inlet flow expected
in Cook Inlet.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale 120 125 130 131 138 139 150 172-174 176.
		 Storm 119.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...SEB
SOUTHCENTRAL ALASKA...CB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...VR
MARINE/LONG TERM...MK/ED