Small Craft Advisory 67, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
149 PM AKDT Thu Aug 20 2020

.SYNOPSIS...

Above normal temperatures continue across Northern Alaska beneath
a ridge of high pressure. A few showers and isolated thunderstorms
are possible from Fairbanks east and in the Eastern Brooks Range
today, and from Tanana east tomorrow. Stratus remains on the North
Slope and on the West Coast with onshore flow. This beautiful
stretch of weather will come to an end this weekend as a weather
front will bring rain to the West Coast by Saturday morning,
eventually spreading east to Fairbanks and the Eastern Interior by
early Sunday morning.

&&

.DISCUSSION...

An upper level closed low that was located south of Yakutat
yesterday has moved to SW of Ketchikan. An upper level low
associated with this feature is centered south of Northway, with
the associated surface low near Glennallen. This feature continues
to advect moisture into the Interior from Fairbanks east,
providing clouds and scattered showers. From Fairbanks west,
ridging is dominant with mostly clear skies for all areas inland
of the coast. Onshore flow from the dome of high pressure over the
Bering Sea is allowing stratus and clouds to linger along the
coast.

Between the ridges extending from the Bering Sea NE and from
Ketchikan NW lies a weak thermal trough over the Eastern Brooks
Range. This area may see isolated thunderstorms this afternoon as
a shortwave trough passes to the north along the Arctic Coast.

The next notable weather system will arrive to the West Coast on
Saturday, bringing rain. Thunderstorms can be expected on the
leading edge of this front as it moves into the Western Interior
on Saturday afternoon, and again in the Eastern Interior on Sunday
afternoon as it progresses eastward. Behind this front, Northern
Alaska enters a troughing pattern with cooler temperatures and
more showers expected into next week across the forecast area.

Models...
The GFS and the NAM currently show better timing regarding the
weather front and associated shortwave moving west to east across
the North Slope, with the ECMWF and HRRR solutions being too
slow. Looking ahead into Sunday, the NAM is much sharper with the
shortwave at the leading edge of the longwave trough moving into
the West Coast and then into the Interior. As a result, forecast
rainfall totals are much higher than in the GFS and ECMWF model
runs that reached that time frame yesterday. The GFS has also
increased its rainfall totals for Saturday night and Sunday in the
Western Interior, with both models putting the highest amounts on
the west slopes of the Alaska Range. Thunderstorms can be
expected on the leading edge of the front where it passes during
the afternoon hours. At this time it appears that this will be in
the Western Interior on Saturday and east of Fairbanks on Sunday,
with stratiform rain beginning in Fairbanks early Sunday morning.
The timing of the forecast reflects the timing of the GFS and
ECMWF, while the NAM solution is a bit slower.

North Slope and Brooks Range...
Isolated thunderstorms are expected in the eastern Brooks Range
this afternoon as a shortwave trough passes just to the north of
the weak thermal trough in place. Otherwise expect mostly clear
skies and warm temperatures to continue through Saturday in the
Central and Eastern Brooks Range, with stratus lingering along the
coast. At this time, expect that the bulk of the precipitation
from the weather front moving in from the west will fall south of
the Brooks Range.

West Coast and Western Interior...
Fog and stratus remains over much of the West Coast, Lower Yukon,
and Yukon Delta from Kotzebue south. The Western Interior remains
clear. Expect these conditions to persist until Saturday when the
weather front arrives, spreading precipitation from west to east.
Isolated thunderstorms will occur ahead of the front in the
Western Interior on Saturday afternoon before the bulk of the
rainfall arrives. Expect showers and cooler temperatures behind
the front.

Central and Eastern Interior...
A few isolated showers and thunderstorms are expected from
Fairbanks east today, but otherwise expect mostly sunny skies and
warm temperatures to continue through Saturday. A weather front
will arrive on Saturday night and spread rain from west to east
with cooler temperatures and more showers behind it.

Coastal Hazard Potential Days 3 and 4...
Exposed south facing capes and shores in the Bering Sea including
Nome may see water levels 1-2 feet above the normal high tide
line on Saturday and Sunday with S and SE winds along and behind a
weather front. Flooding is not expected at this time.

&&

.FIRE WEATHER...

Above normal temperatures will continue into Saturday for most of
Northern Alaska. Minimum RHs will dip into the 30 and 40 percent
range over much of the Interior during the day, but overnight
recovery will be excellent. Isolated thunderstorms are expected
east of Fairbanks and in the Eastern Brooks Range this evening,
east of Fairbanks tomorrow, and in the Western Interior on
Saturday.

&&

.HYDROLOGY...
The Chisana River at Northway has been reported to be high after
~0.5" of rain fell in its basin overnight. The river is expected
to crest this afternoon and slowly fall afterwards. Flooding is
not expected. For the latest river forecasts and conditons, visit
www.weather.gov/aprfc

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
None.
&&

CHRIEST AUG 20