Small Craft Advisory 133, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
229 PM AKDT Wed Sep 27 2017

.DISCUSSION...Main concern in the forecast area will be potential
for high surf on Thursday night through Saturday night along the
Chukchi Sea coastline west of Barrow. Models continue to show some
differences in location of the low position and track with the
Canadian leaning towards the ECMWF solution which would place the
upper level low closer to the Barrow coast (roughly 150 NM
offshore), while the GFS/NAM lags behind in both timing and
position with the low roughly 250 nm north of Barrow by Friday
morning.

Aloft...At 500 mb, a shortwave feature currently moving over the
Bering Strait and Chukchi Sea today will continue to move east
into Northwest Alaska and the Seward Peninsula this evening. This
feature will merge the large wave pattern with the upper level
low positioned over the Arctic Ocean with extending longwave
trough over Western Alaska. This trough and associated surface
front will move across the eastern Brooks Range to the Central
Interior Thursday night into Friday. The upper level low will
continue east to be around 350 nm northwest of MacKenzie Bay by
Saturday morning. An upper level ridge currently residing over
eastern Alaska and western Canada will shift east tomorrow.
An upper level ridge over eastern Siberia will build east over
the Bering sea by late Thursday and over western Alaska Friday. A
broad upper low with several weak shortwaves over the Gulf of
Alaska will persist through late Friday.

Surface...A 995 mb low located 275 nm north of Wrangel Island
will move southeast towards the western Arctic Coast through
Friday morning and be a 992 mb low roughly 250 NM north of Barrow
by Friday morning. This low will move east and remain roughly 200
NM offshore as it moves into the Beaufort Sea coast through
Saturday morning. As this front moves east across the North Slope
the ridge of high pressure will build north over the Bering Sea
and push into Yukon Delta area tomorrow and southwest Interior
tomorrow night. Leeside troughing will continue north of the
Alaska Range this evening and continue into Thursday.

Arctic Coast and Brooks Range...As mentioned above a weather
front will over the western Arctic Coast this afternoon which will
result in a wintry mix of rain and snow to the area today. This
will change over to snow tonight and then spread east through
early Friday. Although mentioned differences in model low track,
in either case expected northwest winds strengthening from 15 to
20 kt winds tomorrow to 25 to 30 kt winds by tomorrow evening.
with strong west winds spreading east along the coast Thursday
night, reaching Barter Island by Friday morning. Rotating around
the low feature there will be another energy brining precipitation
from west to east across the Brooks Range and Arctic Coast staring
on Friday night over western Brooks Range spreading east into the
eastern Brooks Range by Sunday. Will need to monitor this
situation with snow amounts closely as potential exists for 3 to 5
inches of snow in 24 hour period impacting areas along and east of
the Dalton Highway Saturday  into Sunday.

Eastern and Central Interior...Cloud cover will increase
overnight as rain showers will develop this evening across western
Alaska Range and then spread to Middle Tanana valley 4 AM
tomorrow morning. As expected with the leeside trough the gap
winds near the Alaska range passes are underway with up to 45 mph
being recorded Fort Greely area. Gap winds will continue to be
strongest along the Richardson Highway corridor between Delta
Junction and Summit Lake but will slowly taper off tomorrow
morning. Snow levels will start out around 6000 ft on Thursday and
will slowly fall through the evening to 1500 ft overnight. There
could be some rain and snow mixed areas lingering across the area
on Friday morning. Colder air will push across the area Friday
into Saturday. Temperatures will cool towards slightly below
normal values through Saturday. By Saturday, morning lows will be
generally in the mid to upper 20s and daytime highs struggling to
get into the 40s. There's a slight chance of snow for Saturday
morning from the Fairbanks airport northeast to the White
Mountains.

West Coast and Western Interior...Mostly clear skies across the
West Coast but as the shortwave moves across the area, precipitation
chances increase across the Seward Peninsula tomorrow and extend
to the coastline from Hooper Bay to Koyuk for scattered showers.
Expect mainly rain south of Deering with a wintry mix to the
north. High pressure will then build over areas from Seward
Peninsula southward with drying conditions. Although warmer
temperatures today, expecting cooling trend to occur tomorrow
through Saturday.

Coastal Hazard Potential Days 3 and 4...Models still continue to
show differences in the track of the low pressure moving across
the Arctic, which will impact the strength of the winds Thursday
through Saturday morning. Continued with the special weather
statement to highlight the uncertainty, but a potential for
elevated surf conditions for areas along the Chukchi Sea
coastline to Barrow can be expected. At this time looking at 25
to 30kt winds with 30 to 35 kt wind gusts.

.AFG WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory for PKZ225-PKZ225-PKZ230-PKZ235-PKZ245.
&&

Sep 17