Flooding in Alaska, August 19 to 25, 2024

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
441 AM AKDT Mon Aug 19 2024

.SYNOPSIS...
High surf advisories still in effect through Monday morning
for the west coast. Showers will push inland across Alaska
as a front moves through the western Interior. There will be some
gusty westerly winds over the Central and Northern Interior
Monday afternoon and evening as the same front approaches the
Central Interior. Another strong storm is set to impact the west
coast Tuesday into Wednesday with strong winds and the potential
for coastal flooding.

.DISCUSSION...
Upper Levels and Analysis...A Longwave trough will persist over
much of the state on Monday. The shortwave will push through the
Interior on Monday bringing rain and gusty westerly winds. Slight
ridging over the Interior on Tuesday then The remnants of Typhoon
Ampil moves into the western Bering on Tuesday then over the
Chukchi Sea by Wednesday afternoon. Moist southwest flow over
much of the state Wednesday and Thursday as a longwave trough
pattern persists through late next week. Gusty winds likely
to persist over higher terrain of the Interior Wednesday
and Thursday.

Central and Eastern Interior...Rain showers developing
over the Middle Tanana Valley this morning and will continue
through Monday. Gusty west winds expected over higher Terrain of
the Steese Highway and also the Dalton Highway Summits through
early Tuesday morning. Some winds could mix down to valley level
on Monday. Tuesday a bit drier but more rain chances and cooler
temps Wednesday through Friday. If the Interior clears out and
winds diminish there could be some frost around the Interior
Tuesday morning. Cooler and wetter pattern will persist through
the week. Gusty southwest winds likely to persist over higher
terrain of the Interior Wednesday and Thursday.

West Coast and Western Interior...High Surf advisories still in
effect for elevated waters and the potential for beach erosion
through Monday morning. Winds still gusty currently but will
diminish some this afternoon then picking back up on Tuesday as
the next system approaches. Coastal Flood Watches will likely
be issued once the current high surf Advisories end.

The remnants of Typhoon Ampil will impact the west coast Tuesday
into Wednesday more strong winds and rain. Confidence is high
this low will also produce elevated surf and coastal flooding
impacts with the highest water over E Norton Sound due to strong
southwestly winds and a dynamic fetch. The track of the low is
coming more in line with each model run and the low's track will
push through the western Bering on Tuesday then to Saint Lawrence
Island by Wed morning, and then to the Chukchi Sea by Wed
afternoon. It looks to be a strong storm but not as strong as
Merbok. The core of strongest southwest winds beginning Wed
morning through Wednesday evening in the Norton Sound. There will
also be the potential for gusts to 60 mph over Saint Lawrence
Island and the Bering Strait.

North Slope and Brooks Range...Rain and showers are spreading
cross the N Slope and Arctic as a low over the Bering shifts
north, and will then cross the Arctic on Monday. West winds will
move in behind this low and bring in showers and cooler temps, and
eventually drier weather by Tue. Another front from the south
moves into the Brooks Range Tue night and Wed with south gusts to
40 mph in the Brooks Range, and more rainfall with snow above
4500 feet.

Extended Forecast Days 4-7...High impact storm for the west coast
by mid week. Most of the state will remain in a cool long wave
trough pattern with chances for precip for much of the week.

Coastal Hazard Potential Days 3 and 4...A strong coastal low, the
former remnants of current Typhoon Ampil, is projected to move
into the YK Delta and Norton Sound Tuesday into Wednesday with
gale force southwesterly winds and potential for coastal flooding.
The current track and strength could bring elevated water levels
of 4 to 6 feet for most areas but the highest water levels near
Koyuk with elevated water around 8 to 10 feet above the normal
high tideline.

.FIRE WEATHER...Cooler temperatures and showers expected
on Monday and much of next week. Gusty winds will continue over
the higher terrain of the Interior on Monday as a front moves
through the area.

.HYDROLOGY...2-3 inches of rain over past two days along with
another 1-2 inches during the next 12 hours will cause rapid
increases in stream levels. Tributaries to the Koyukuk River could
reach bankfull levels by Sunday evening or Monday morning.

The Koyukuk River at Bettles and Allakaket will rise
significantly over the next 24 hours and crest late Monday or
Tuesday. River levels at Bettles and Allakaket are currently
forecast to remain below flood stage. The Koyukuk River at Hughes
is expected to crest Wednesday below flood stage.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Flood Watch for AKZ812-831-832.
     High Surf Advisory for AKZ817-818-820-822-824.
     High Wind Watch for AKZ821.
     Wind Advisory for AKZ832.
     Wind Advisory for AKZ834.
PK...Small Craft Advisory for PKZ801-802-850-853.
     Small Craft Advisory for PKZ803-805-858.
     Small Craft Advisory for PKZ804-852.
     Gale Warning for PKZ807-810-856.
     Gale Warning for PKZ808-855.
     Gale Warning for PKZ809.
     Small Craft Advisory for PKZ811-857.
     Small Craft Advisory for PKZ812.
     Small Craft Advisory for PKZ813.
     Small Craft Advisory for PKZ814-860.
     Small Craft Advisory for PKZ815.
     Small Craft Advisory for PKZ859.
     Gale Warning for PKZ861.
&&