Gale Warning 444, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
529 AM AKDT Mon Aug 1 2022

.ANALYSIS AND UPPER LEVELS...

A low pressure system works its way onshore over Southwest Alaska
this morning, tracking eastward over the Western Alaska Range and
then into the Gulf of Alaska by tonight. The associated front will
push over Southcentral today. A zonal jet situated over the
Aleutians is helping to guide the low, rather quickly, towards the
Gulf. This system will produce active weather for Southern Alaska
through tonight, followed immediately by a shortwave that will
allow for some lingering showers on Tuesday. Upper level ridging
crosses over Southern Alaska Tuesday night and Wednesday before
the next Bering low moves in. The second system enters the western
Bering on Tuesday and will track towards the Bering Strait through
Thursday. Its front is expected to push against the Southwest
Coast by Wednesday afternoon. Anticipate another round of active
weather by Wednesday night.

&&

.MODEL DISCUSSION...

Models remain in good overall synoptic agreement through the short
term. There remains minor inconsistencies with the low center and
speed of the Bering Sea system on Wednesday.

&&

.AVIATION...
PANC...Ceilings and visibilities may drop to MVFR with an
incoming front, along with some light rain today. Turnagain arm
winds will pick up this afternoon but should diminish again by
this evening. Periods of light rain may continue into tonight but
cloud ceilings should increase to around 5000 feet.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today
through Tuesday)...

Clouds have begun to increase this morning as a low pressure
system moves towards Southcentral. The rain will begin this
morning across the Kenai Peninsula and move north. Rain will start
by late morning to around mid-day from Anchorage and north into
the MATSU valleys. The Turnagain winds will pickup and bend into
west Anchorage this afternoon and then quickly dissipate by this
evening. The rain will shift east towards the Copper River Basin
this afternoon as the upper level low moves across the northern
Gulf. By tonight the low will move into the northeast Gulf with
rain ending across much of the area. However, rain will linger
across the eastern Copper River Basin through Tuesday morning. On
Tuesday north and northwest gap winds will develop as the low
moves east and the pressure gradient increases. Another quick
moving upper level low moving out of western Alaska will
transition to an open wave and will reinforce the northerly gap
winds Tuesday evening through Wednesday morning. This will produce
gusty west to northwest winds across the Barren Islands and into
the Gulf, with gusty northerly winds across Seward and
Resurrection Bay these northerly winds will allow temperatures to
climb in the 70s around the Seward area Tuesday and Wednesday.
Additionally, gusty west winds are expected near Whittier. As the
shortwave moves across the area expect a few showers to develop
Tuesday near most inland valley locations. On Wednesday a ridge
of high pressure will move over the area producing warmer than
normal temperatures in the 70s to near 80 and mostly sunny
conditions.

&&

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

A fast moving low pressure system will continue to sweep eastward
across Southwest Alaska today, bringing widespread wetting rains
with storm total rainfall amounts generally 0.5 inches or less
through early this afternoon. The low's occluded front stretches
across the Southwest from the Kuskokwim Delta coast to the
northern Alaska Peninsula this morning, and it should continue to
track quickly inland today, with steady rainfall giving way to
scattered rain showers behind the front as it progresses north and
east. After the passage of the front, west to southwesterly winds
gusting up to 25 mph will develop through the coastal regions of
Bristol Bay today as well, before diminishing this evening as the
boundary layer decouples from the stronger synoptic flow.

As the low tracks east into Southcentral Alaska Monday evening,
broad ridging building in over the Bering Sea will be hindered in
Southwest Alaska as a shortwave trough riding atop the ridge
strengthens over the northern Bering and moves into Southwest
Alaska Monday night. Thus, cool, moist conditions will continue
for a little longer as the shortwave promotes continued rain
showers, especially over the Kuskokwim Delta into Tuesday morning.
However, with this shortwave tracking as quickly eastward as the
previous system to Bristol Bay and into the western Gulf of Alaska
by Tuesday afternoon, expect the areas of showers to move quickly
into Bristol Bay and the Lower Kuskokwim Valley by the afternoon,
and end shortly thereafter.

With the shortwave out of the picture by late afternoon on Tuesday
a surface ridge finally moves in over Southwest Alaska, allowing
for some partial clearing and a bit warmer high temperatures into
the mid 60s. Tuesday night, subsidence and light winds under the
ridge will provide an opportunity for fog to develop. Any fog,
however, should clear for a mostly dry Wednesday with the upper
level ridge remaining in place, and high temperatures will start
to approach 70. This will be short-lived, though, as the next low
and front start approach the Southwest coast by Wednesday evening,
with rain in the forecast once more.

&&

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

Active weather continues across the Bering Sea over the next
several days with multiple lows expected. First, a fast moving low
centered just off the Southwest coast will track inland later this
morning. A swath of gale force winds associated with this low
continues to track along the eastern Aleutians, with gusts just
below storm force continuing to be observed in the core of the
strongest winds. These winds will track east to the southern
Alaska Peninsula before weakening below gale force sustained later
this morning. Gusty winds will continue to be a concern out of
gaps in the Aleutian Range south of the Alaska Peninsula,
however, as the low tracks eastward into the Gulf of Alaska and a
broad ridge builds across the Bering. Gusty gap winds then
gradually diminish through Tuesday as the surface ridge axis
approaches the Alaska Peninsula.

Out west, another developing low tracks toward the western
Aleutians, its front reaching the islands this afternoon. Moderate
rainfall and easterly winds up to small craft strength will
accompany the front late Monday night, extending as far as the
eastern Aleutians later by Tuesday. As the low enters the Bering
Tuesday night, the rain should let up for the most part with the
front lifting across the Aleutian Chain and reaching the Pribilof
Islands. Winds, however, intensify for the Chain out of the south
and shift southwesterly through Wednesday morning. Cold air
wrapping into the southern side of the low will lead to portions
of the western and central Aleutians seeing gale force winds on
Wednesday. After this, the low continues to track further into
the Bering, its front reaching the Southwest coast by Wednesday
afternoon before the low tracks into the northern Bering Wednesday
night.

&&

.MARINE (Days 3 through 5 - Wednesday through Friday)...

Gulf: Low pressure will bring enhanced waves over portions of the
Gulf on Wednesday. This system will move fast and high pressure
will follow. Another trough will move into the western Gulf early
Thursday. Potential southwesterly gales will be possible into the
Shelikof Strait as the trough first overspreads Kodiak Island, but
quickly weaken and become westerly Thursday afternoon. Offshore
seas may build to 10 to 12 feet on Wednesday - Thursday.

Bering: A North Pacific low moves into the Western Aleutians and
western Bering Sea on Tuesday/Wednesday. The low is forecast to
push into the Central Bering on Thursday with a surface pressure
of 1000 mb. Nevertheless, areas of gales may be possible on the
south side of the low from the Western and Central Aleutians into
the Pribilofs through Wednesday. Forecast confidence decreases by
Thursday with timing and placement of the low into the west coast
of Alaska a bit more uncertain. Seas to peak at 10 feet.

&&

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

The GFS and ECMWF bring a broad area of positive height anomalies
over the north Pacific. However, late in the period the GFS has a
distinct area of negative height anomalies over Mainland Alaska.
Strong high pressure in both the upper levels and at the surface
is forecast to retrograde and meander across the mid-latitudes of
the Pacific between Alaska and Hawaii. This will allow for a
fairly progressive pattern across southern Alaska. These features
will bring chances of rain to the Aleutians eastward into the
southern mainland. Then an Arctic upper low is forecast to edge
southward toward Interior Alaska late next week, bringing cooler
temperatures.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale 155
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...KM
SOUTHCENTRAL ALASKA...RC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CQ
MARINE/LONG TERM...PJS