High Surf Advisory 6, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
605 AM AKDT Sat Aug 11 2018

.DISCUSSION...

Synopsis...An overall pattern change is expected through the
weekend and into next week, as the remnants of Typhoon Shanshan
enter the forecast area Sunday. This will bring increasingly
wetter conditions across the West Coast and Western Interior, with
locally heavy rainfall possible. Winds will strengthen across the
West Coast and portions of the Western Interior. Across the Alaska
Range strong southerly Chinook winds are expected to develop
Sunday and continue into Monday.

Models...OOZ model runs initialized well against the 11/06Z
surface analysis, with the high located over the East Siberian Sea
around 4 mb higher than any model guidance. While models are in
better agreement with the handling of Shanshan, there still
remains a fair spread in models regarding timing of the remnants
Monday and Tuesday, with the GFS being the slowest and the ECMWF
being the fastest, with the NAM falling in between.

Aloft...A broad long wave trough remains over the Bering Sea today
containing a 540 dam center over the Gulf of Anadyr. A 588 dam
center of high pressure is over the North Pacific extending inland
over the Interior. A 527 dam low 500 NM NW of Demarcation Point,
with a shortwave extending from Wainwright east.

The 527 dam low 500 NM NW of Demarcation Point will remain in
place through the next several days, maintaining upper level
troughiness across the eastern Arctic Coast and north slope.
Several shortwaves will rotate through the flow as ridging builds
in across the western Arctic Coast.

The long wave trough axis over the Bering will slowly shift east
through tonight, with the 540 dam low over the Gulf of Anadyr
slowly drifting NW over Chukotka. By 12Z Sunday the 536 dam
remnants of Shanshan will be located north of Akutan. As the low
moves inland, the ridging over the North Pacific will deepen and
amplify as it shifts east, still exerting influence over the
eastern Interior.

By 12Z Monday, the remnants of Shanshan weaken to 538 dam as they
move inland to be near Russian Mission, while the meandering 540
dam low over Chukotka weakens to 542 dam as it reemerges over the
Bering Sea. The ridging over the North Pacific will be shunted
further east. By 12Z Tuesday, the low over the Western Interior
moves little but weakens to 546 dam and will slowly become
absorbed into the general flow, while the low over the western
Bering Sea moves southeast to be north of St Paul Island.

Surface...A ridge of high pressure over the Chukchi Sea extends
east to Barrow today, and will remain in place, while a 1004 mb
area of low pressure 500 NM NW of Demarcation Point persists
through the weekend. A cold front associated with this low will
move south across the Arctic Coast Sunday night into Monday. A
1010 mb low over the Gulf of Anadyr this morning will persist
through the day before dissipating tonight. A 1003 mb trough
extending from Nunivak Island to Atka this morning will weaken and
dissipate by 00Z Sunday, with associated front moving inland.
Remnants of Shanshan are south of Adak this morning and will move
to be over Akutan as a 975 mb low by 12Z Sunday, to near Cape
Newenham as a 979 mb low by 00Z Monday, to a 986 mb low near
Marshall by 12Z Monday, and continuing to weaken and slowly move
eastward Monday afternoon and Tuesday. As the remnants of Shanshan
move inland, leeside troughing will develop north of the Alaska
Range and deepen Sunday and Monday.

Arctic Coast and Brooks Range...Partly sunny skies expected along
the coast for much of the next several days with partly cloudy
skies further inland. Areas of fog will continue along the eastern
Arctic Coast. Shower activity this morning from Barter Island
east will taper off and drier conditions are expected through
Sunday. Afternoon temperatures in the 40s along the coast today
and Sunday, with highs in the 50s to lower 60s inland. A weather
front will move across the Arctic Coast Sunday night into Monday
bringing cooler temperatures and isolated to scattered showers.

West Coast and Western Interior...Generally wet conditions
expected to continue across the West Coast and Western Interior.
Scattered showers today and tonight will produce 0.25 to 0.50
inch of rainfall through tonight. Showers will become more
numerous going into Sunday and Monday as the remnants of Shanshan
move across. Moisture will surge across the coast, bringing
periods of heavy rainfall. Widespread rainfall accumulations of 1
inch likely, with isolated higher amounts in upslope areas. In
addition to the rainfall, strong and gusty winds are likely along
the coast and strong wind headlines will likely be needed. A Wind
Advisory has been issued for strong southeasterly winds in zone
227 on Sunday. Winds through the Bering Strait and Chukchi Sea
will shift to the north and increase in speed, pushing water
towards the north coast of St Lawrence Island. This could create
the potential for high surf Sunday night into Monday.

Central and Eastern Interior...Fairly quiet conditions across the
Central and Easter Interior today and tonight, with only isolated
showers. As the remnants of Shanshan move eastward, strong
southerly Chinook winds are expected to develop on Sunday for
passes in the Alaska Range, continuing through Monday morning. A
High Wind Watch has been issued for zones 223, 225, and 226.
Strong southwesterly winds are expected to develop west of Tok on
Sunday. Rain chances will increase for the region Sunday
afternoon onward, but for areas from Fairbanks south, rain chances
will be a little more limited due to being shadowed out. A steady
warm up in temperatures is expected across the Interior through
Sunday as ridging aloft builds across the area, with highs pushing
into the upper 60s to around 70.

Coastal Hazard Potential Days 3 and 4...High surf possible on the
north side of St Lawrence Island on Monday.

&&

.FIRE WEATHER...Fire weather activity will remain low through the
weekend. RH values are expected to remain above 30 percent in
most areas. Lowest RH values will occur across the Yukon Flats
this afternoon and may briefly touch 30 percent. Strong southerly
Chinook expected to develop along the Alaska Range by Sunday
afternoon and continue through midday Monday. For the latest
information go to www.weather.gov/arh/fire.

&&

.HYDROLOGY...Flood Advisory continues for Mile 6 Tetlin Rd with high
water likely through the weekend. High water is expected on rivers in
the Tanana Valley through the weekend. However, rivers have all
crested and are falling across the Interior. Expect rises next
week as remains of Typhoon Shanshan moves across Interior. For the
latest information go to www.weather.gov/aprfc.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Flood Advisory for AKZ224.

High Wind Watch for AKZ223-AKZ225-AKZ226.

Wind Advisory for AKZ227.

Small Craft Advisory for PKZ225-PKZ230.
&&

EB AUG 18