Flood in Alaska, August 3 to 4, 2019

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
557 AM AKDT Sat Aug 3 2019

.DISCUSSION...
Several ongoing areas of concern across Northern Alaska are
expected through this weekend. Strong southwest winds across the
West Coast are expected to cause coastal flooding along the Norton
Sound Coast and Yukon Delta, as well as high surf as far north as
Point Hope. Heavy rain will affect much of the West Coast and
Interior, causing rises in nearly all rivers. This will be
particularly problematic for the West Coast, where record rainfall
has already fallen and swollen rivers will be met by storm surge
at the coast. The North Slope will feel the effects of this storm
system Saturday into Sunday as strong winds and elevated surf are
expected.

Aloft 500 mb...
A deep longwave trough is firmly entrenched over eastern Siberia
and the Bering Sea. Embedded within this feature, are several
height minima, with our current troublemaker sitting over the
Bering Strait. Steady southwesterly flow extends well into the
subtropical Pacific, pumping deeply saturated air straight into
the West Coast of Alaska. Shortwave features will continue to
sweep eastward from Siberia over the next few days, though high
pressure over the Gulf of Alaska is expected to strengthen in
place and gradually shut off access to the atmospheric river
currently inundating the state by mid next week.

North Slope and Brooks Range...
Low pressure centered over the Bering Strait will race
northeastward, crossing the western Brooks Range Saturday morning,
and emerging into the Beaufort Sea near Prudhoe Bay in the
afternoon. Rain, heavy at times, and strong winds are expected.
Modest east winds along the coast early Saturday morning will
begin to turn onshore as the low draws near, then turn west and
increase to 30 to 40 mph as the low sweeps east. Up to half an
inch of rain is expected along the coast from Utqiagvik west,
with around a quarter inch farther east. Southwesterly upslope
favored areas of the western and Central Brooks Range could see
well in excess of an additional inch of rain through Sunday. A
burst of cold air will follow the low east, with temperatures
dropping sharply across the region late Saturday into Sunday. Wet
snow will be possible across the higher elevation of the Brooks
Range generally above 3000 feet. This will include Dalton passes
where a slushy accumulation of a half inch is possible Sunday
morning.

West Coast and Western Interior...
Strong southwest winds will continue to lash the Norton Sound and
Yukon Delta into Saturday afternoon. Record rainfall has already
fallen across many areas near the coast and showers are expected
to persist into the late morning as the low tracks northeast into
the Brooks Range. A follow up shot of heavy rainfall is expected
to move north into the Yukon Delta early Sunday and reach the
Norton Sound early Monday. Farther north, heavy rainfall and
strong winds will persist into this afternoon for areas along the
Chukchi Coast and western Brooks Range. Southwesterly upslope
favored areas will again be favored for the highest additional
accumulations through late Saturday. Much of the coastline will be
impacted by high surf and/or coastal flooding. For details, see
the COASTAL HAZARDS section.

Central and Eastern Interior...
Another round of rain expected today as a weather front sweeps
east across the region. Steady rain and gusty southwest winds
along the front will impact Minchumina to Stevens Village by 7AM,
then Fairbanks to Eagle around 10AM. Brisk west winds and showers
will linger behind the front with cooler high temperatures
expected through the weekend. Around a tenth to a quarter inch of
additional rainfall can be expected for most areas through Sunday.

Coastal Hazards...
Coastal Flood Advisories have been issued for the Norton Sound
Coast as well as the Yukon Delta. A strong southwesterly fetch
extending well south of the Aleutians will push water up along the
coast. The event is expected to peak around noon Saturday. Storm
surge is expected to reach 6 to 8 feet above normal high tide
along the southern Seward Coast west of Golovin. From Golovin to
Shaktoolik, 8 to 11 feet of surge is possible. The Yukon Delta
coast will see up to 4 to 6 feet of surge above the normal high
tide. Storm surge is expected to push up into rivers already
swollen from heavy rainfall, and as a result Flood Watches have
been issued for these areas. Farther north along the Chukchi and
Arctic coasts, the main threat will be elevated water levels and
high surf. Some beach erosion will be possible.

&&

.FIRE WEATHER...
Strong southwest flow across the state had brought significant
rainfall to much of the state with much of the Interior expecting
around a tenth to a quarter inch of additional rainfall today. A
cold front will sweep east through the Interior today, followed by
cooler temperatures and relative humidity well above 40 percent.
However, winds will be gusting from the southwest around 15 to 25
mph. Another round of potentially heavy rain is expected to impact
the Interior Monday into Tuesday.

&&

.HYDROLOGY...
Flood Watches remain in effect for all rivers draining into the
Norton Sound. This includes the Unalakleet, Shaktoolik, Koyuk,
Niukluk, Snake and Nome Rivers. Rivers are rising from several
days of heavy rain and will meet storm surge near the coast. This
may locally enhance flooding near the coast.

Interior rivers are showing rises as rainfall well in excess of
an inch has fallen in most areas. Guidance does not show an rivers
approaching flood stage yet, but sharp rises are still likely
through Sunday. Another shot of significant rainfall is likely
Sunday for the West Coast and Monday for the Interior as the
atmospheric river event continues to inundate the state.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Coastal Flood Warning for AKZ211-AKZ212-AKZ214.

High Surf Advisory for AKZ204-AKZ207-AKZ209-AKZ210-AKZ213.

Flood Watch for AKZ211-AKZ212.

Small Craft Advisory for PKZ235-PKZ240.

Gale Warning for PKZ200-PKZ210-PKZ215-PKZ220-PKZ225-PKZ230-
PKZ245.
&&

COWMAN AUG 19

Special Weather Statement
National Weather Service Fairbanks AK
638 AM AKDT Sat Aug 3 2019

AKZ203-204-040200-
Central Beaufort Sea Coast-Eastern Beaufort Sea Coast-
Including Nuiqsut, Prudhoe Bay, Alpine, Deadhorse, Kuparuk,
Kaktovik, and Flaxman Island
638 AM AKDT Sat Aug 3 2019

...Strong Winds and High Surf Over the Eastern Arctic Coast
Saturday night and Sunday...

Northwest winds gusting to 50 mph area expected to develop over
the Eastern Arctic Coast tonight and continue into Sunday. This
is expected to cause high surf and coastal erosion as well.

Locations affected will be largely dependent on exact track and
intensity of the low pressure system. Kaktovik and Point Thompson
appear likely at this point to experience the strongest winds.

Areas west to Prudhoe Bay may also experience strong winds and
high surf. Updates to the forecast will be made accordingly.

AKZ201-202-040200-
Western Arctic Coast-Northern Arctic Coast-
Including Wainwright, Atqasuk, Point Lay, Cape Lisburne,
Utqiagvik, Alaktak, Pitt Point, and Nulavik
638 AM AKDT Sat Aug 3 2019

...Strong Winds and Elevated Surf Expected Saturday...

East winds this morning will gradually turn northerly and increase
to 30 to 40 mph by this evening. Elevated surf and coastal erosion
are possible.

Winds will turn westerly and decrease to around 20 mph by early
Sunday.