High Wind Warning 15, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
1136 PM AKDT Sun Aug 18 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: This
afternoon through Wednesday)...

A cold front associated with a strong low in Western Alaska is
tracking through Southcentral Alaska this afternoon and will
reach the AlCan border late tonight. Strong southerly winds have
been occurring ahead if this front with gusts 45 mph or higher in
Anchorage, Seldovia and Glennallen today. As this front passes
through, winds will shift to the southwest and generally not be as
strong. The main exceptions will be in and along Shelikof Strait
and Cook Inlet where the southwesterly winds will increase this
evening and remain strong overnight due to pressure rises in the
constricted terrain.

The 500 mb trough will take longer to move through Southcentral
and will track through the area Monday. As the main upper level
low is to the north of us, this upper trough will keep more clouds
cover and have shower potential farther north so the Mat-Su
valleys and Copper River Basin have the best chance for lingering
showers Monday. A surface trough will also develop along the north
Gulf coast Monday as the trough moves through and higher pressure
builds in from the west. this will increase northerly winds
especially near Kodiak, Seward, and Whittier Monday and Monday
night.

Generally sunny skies under high pressure will be over the region
on Tuesday before the next front moves into the region on
Wednesday. this front should bring more rain with it, but it
should move through fairly quickly.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA/ALEUTIANS
(Days 1 through 3)...

A Flood Warning is in effect through 6pm Monday for high winds
backing up flow along the lower Kuskokwim River and Kuskokwim
Delta.

Satellite image showed the Bering storm made landfall on the
Mainland this morning just north of Mekoryuk. ASCAT and surface
observations confirmed a narrow band of gusty winds ranging from
50 to 60 mph from Quinhagak north to Kipnuk inland to Bethel and
Tuluksak today. This narrow band of higher wind gusts diminished
this afternoon after peaking at 58 mph in Bethel. Flooding from
these winds pushing water up the Kuskokwim River in Bethel and
Tuntutuliak has been reported. Elsewhere, wind gusts ranged from
40 to 50 mph into this afternoon. Winds will continue to diminish
in to the evening. Widespread rain showers from the Alaska
Peninsula northward to Newtok inland to Lower Kalskag and
southeastward to Iliamna diminished quickly in the wake of the
storm's cold front with isolated ones in its wake through this
evening. Gale force winds in the Bering Sea will diminish this
afternoon.

A North Pacific High building just south of the Aleutians moves
eastward through Tuesday resulting in a period of calm conditions
for Shemya and the Western Aleutians through tomorrow and the
Central Aleutians to the Mainland tonight into Tuesday. A weak
low pressure just south of Adak could enhance the southerly/
southwesterly flow into the Central Aleutians, AK Pen and the
Mainland tomorrow and Tuesday.

Former tropical storm Ampil (Typhoon Ampil) moves northwest of
Shemya tomorrow bringing southwesterly gale force winds and
precipitation to Shemya, the Rat Islands and the Western Aleutians
as it moves northwest of Shemya overnight. Entering into the
Bering Sea, it intensifies from a 978 mb low to a 965mb low from
Monday morning to Tuesday morning. A wave moving southeasterly
toward Ampil could force the tropical storm into a more northward
direction. The storm's front is likely to reach Adak Monday
evening/Tuesday morning with gusty winds and precipitation.

-DJ

&&

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

The former Tropical Storm Ampil will have moved into the Bering
Strait on Thursday. Generally zonal flow through Friday across the
Bering with several disturbances rotating through the flow. An
upper level trough sweeps from the eastern coast of Russia on
through the forecast period. The trough reaches the western
mainland of Alaska on Saturday and bisects the interior for
Sunday. A surface front develops over western Alaska and moves
into the Gulf of Alaska and interior by Sunday. An upper level low
will form off of Kamchatka on Sunday and become our next weather
maker after the end of the forecast period.

Generally widespread gusty winds across the Bering accompanies
the formation of the front into western Alaska, dissipating late
Friday. The front spreads a wide swath of locally heavy rain
across the western half of Alaska for Thursday and diminishes as
the front moves through the interior. On the tail end of the
front, an elongated band of locally heavy rains will impact the
Aleutians and Alaska Peninsula through early Friday. As the front
passes through Southcentral, it will form a low pressure system
over the Northern Gulf, which will trigger moderate to heavy rain
across Prince William Sound and the Copper River Delta for the
rest of the forecast period. A well developed low pressure system
in the eastern North Pacific will bring heavy rain and strong
winds for next week.

-JR

&&

.AVIATION...

PANC...VFR conditions persist. Gusty southwesterly wind will
increase overnight, peaking before 12Z Monday morning.

&&

SPECIAL WEATHER STATEMENT...RESENT
National Weather Service ANCHORAGE AK
1207 AM AKDT Mon Aug 19 2024

AKZ181-185-191300-
Alaska Peninsula-Eastern Aleutians-
Including the cities of Cold Bay, Sand Point, Unalaska,
and Nikolski
1207 AM AKDT Mon Aug 19 2024

...TRACE AMOUNTS OF ASH POSSIBLE ACROSS THE EASTERN ALEUTIANS AND
ALASKA PENINSULA THROUGH EARLY MONDAY MORNING...

A band of residual ash from the eruption of Sheveluch on the
Kamchatka Peninsula Saturday has moved over the eastern Aleutians
and Alaska Peninsula this evening. Diminishing winds at the
surface and aloft is allowing some of this ash to settle to the
surface, resulting in the potential for trace amounts of ash for
these locations. Any residual ash is expected to diminish by
Monday morning.

People with respiratory ailments in these areas are encouraged to
avoid or reduce outdoor activity to avoid inhaling ash.

Preliminary Local Storm Report
National Weather Service Anchorage AK
1207 AM AKDT Mon Aug 19 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0300 PM     Coastal Flood    Tuntutuliak             60.34N 162.67W
08/18/2024                   Bethel             AK   Public

            Report received before 3 pm from a resident
            in Tuntutuliak that water had entered at
            least two houses. Southerly wind-driven
            surge event leading to high water levels on
            the lower Kuskokwim River.

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
1244 AM AKDT Mon Aug 19 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0300 PM     Coastal Flood    Bethel                  60.79N 161.74W
08/18/2024                   Bethel             AK   NWS Employee

            An NWS employee reports several streets
            flooded in Bethel, including S Harbor Rd.
            Waves of 1.5 ft overtopping the road.
            Southerly wind-driven surge event leading to
            high water levels on the lower Kuskokwim
            River.

&&