Gale Warning 110, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
242 PM AKDT Sat Sep 28 2019

.DISCUSSION...
A front associated with a low moving north along the west coast of
Alaska will bring precipitation (mostly rain) to much of the west
coast and the Interior tonight into Sunday. This system will also
bring strong winds to the Alaska Range. This system will be our
main forecast challenge in the short term.

The models initialize well and are in generally good agreement
with the overall synoptic scale pattern out through early Sunday.
After Sunday morning, the models start to diverge on the exact
timing of the surface surface low that is expected to move north
along the west coast and then will track east along the Arctic
Coast. The NAM move the low to near Utqiagvik much quicker than
the other models and stalls it there longer. The scenario
depicted by the NAM would bring higher water levels and a more
prolonged period of elevated surf to the Chukchi Sea Coast than
the other models. Given that the NAM is currently the outlier, we
opted to lean more to the GFS solution for the moment.

Central and Eastern Interior: A front will bring spread
precipitation into the Interior tonight and Sunday. Snow levels
will rise to the 6,000 to 8,000 foot range as the precipitation
moves in, so for most locations this will primarily a rain event.
In areas north of the Yukon River the precipitation will likely
start off as snow, but will transition to rain. North of Coldfoot,
the snow will be the dominant precipitation type with some spots
seeing an inch or so of accumulation.  Areas from Fairbanks west
will likely see over a half of an inch of rainfall with this
system, with some spots seeing up to an inch. Precipitation with
this system will taper off early Monday for areas from Fairbanks
west, while some rainfall will linger into Monday afternoon east
of Fairbanks. The pressure gradient will tighten up across the
Alaska Range this evening as a surface low moves north along the
west coast As the pressure gradient tightens up strong, southerly
gap winds will develop in the Alaska Range. Wind gusts near passes
are expected to be in the 50 to 60 mph range. Wind advisories
have been posted for zones 225 and 226 beginning this evening and
continuing through Sunday evening in anticipation of the gap
winds. In addition, the setup aloft is favorable for stronger
southwesterly winds along the Alaska Highway from just west of
Tok to Dot Lake. We opted to issue a Wind Advisory for zone 224
for gusts up to 40 mph in this area. A system in the Gulf of
Alaska will spread precipitation into the Interior from the
southeast Tuesday into Wednesday. Most of the precipitation will
be confined to areas southeast of a line from Fort Yukon to Lake
Minchumina. Snow levels are expected to fall below 1,000 feet
during this event.

West Coast and Western Interior: An area of low pressure tracking
to the north along the west coast will spread rainfall over the
area tonight. By the time the system moves out of the area on
Sunday evening, 0.5 to 1.5 inches of rainfall is expected with
this system. Gusty westerly winds are expected around the back
side of the low Monday evening. This will primarily affect Norton
Sound, where gusts of 30 to 40 mph are possible (primarily south
of Koyuk). Some showers will linger across the area on Monday. A
ridge will build over the area on Tuesday will limit the chances
for precipitation. A front will spread precipitation to the west
coast on Wednesday, with showers lingering into Thursday. There
are more substantial chances for precipitation on Friday as a low
moves from the Bering Sea, over the Yukon Delta and up the Yukon
Valley. This system will bring gusty westerly winds to the coast,
although there is disagreement on the exact placement and timing
of the strongest winds at the moment.

Arctic Coast and Brooks Range...Cloudy with southerly winds over
most areas continuing into tonight will keep coastal fog offshore.
Winds will shift to the east-southeast over much of the area
tomorrow as an area of low pressure moves north and east along
the Chukchi Sea coast. Southerly gap winds gusting to 45 mph will
also develop Saturday night through eastern Brooks Range passes
and will impact the Dalton Highway north of Atigun Pass. The
approaching low will deepen just off the coast of Utqiagvik on
Sunday night and sweep east on Monday. This will spread rainfall
across the area Sunday into Monday, mixing with snow on the
backside of the low as cooler air sweeps in some spots in the
Brooks Range may see an inch or so of accumulation. Strong onshore
winds of 25 to 45 mph are likely to areas from Wainwright
eastward on Monday. There is still some uncertainty with the track
of this low at the moment, with the NAM keeping the low in place
near Utqiagvik while the other operational models move the low to
the east quicker. We opted to go more for the GFS solution for
the track of the low; however, we will have to continue to monitor
this area.

Coastal Hazard Potential Days 3 and 4...An area of low pressure
moving east along the Arctic Coast will bring northwesterly winds
of 20 to 30 mph to the Chukchi Sea Coast on Monday. These winds
will cause elevated sea levels and increased wave action. The sea
level is expected increase one to two feet above the normal high
tide line from Utqiagvik west during the day on Monday. There is
still a lot of spread with the models on the exact track and
timing of the low, the the GFS and the ECMWF moving the low much
quicker eastward than the NAM. A low that will move reach the
Yukon west coast of Alaska on Friday has the potential to bring
elevated water levels and surf to parts of the west coast; however,
at the moment the exact details are uncertain at the moment.

&&

.HYDROLOGY...
Rivers and streams are running well below bankfull across the
forecast area. The 0.5 to 1.50 inches of rain forecast this
weekend in portions of the Interior will result in rises on some
drainages, but flooding is not expected.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Advisory for AKZ224-AKZ225-AKZ226.

Small Craft Advisory for PKZ215-PKZ220-PKZ225.
&&

SEP 19