High Surf Advisory 3, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
255 PM AKDT Sat Apr 28 2018

.DISCUSSION...
Active, progressive spring weather pattern continues over northern
Alaska. The main forecast concerns involve a strong late season
low that move east across the southern Bering Sea and into Norton
Sound through late Monday and will bring strong gusty winds and
the potential for high surf and minor coastal flooding to Scammon
Bay, Cape Romanzof, the Yukon Delta coast, and the northern shore
of St Lawrence Island. There remains a great deal of uncertainty
due to significant differences between the NAM, GFS, and ECMWF,
and especially due to a southward deviation of low track and
position with the 28/18Z NAM and GFS. Will have to see what the
the 29/00Z guidance suite has in store to make any decisions
regarding any potential coastal hazards. Elsewhere, south gap
winds in the Alaska Range will continue through the rest of the
weekend into Monday, where a wind advisory will be in effect
starting tonight for the eastern Alaska Range.

West Coast and Western Interior...A weak surface low currently
over the lower Yukon Valley and Delta will continue to bring rain
and snow showers to areas south of the Seward Peninsula this
evening. As it moves further east inland will spread a mix of
rain/snow to areas south of a line from Unalakleet to Minchumina
tonight and snow to the north with snow amounts around an inch.
The main forecast concern will be the low that is forecast to move
east across the southern Bering Sea and possibly into Norton
Sound. Latest 28/18Z model guidance has deviated so that the
forecast track keeps the low south with landfall possibly between
Emmonak and Hooper Bay sometime between midnight Monday night
(NAM) and early Tuesday morning (GFS). This differs significantly
from the 28/12Z ECMWF and previous forecast NAM/GFS tracks where
the low was forecast to move into Norton Sound and then inland.
Gusty winds between 45 and 55 mph from the south to southwest will
develop ahead of the low Sunday persisting into Monday before
shifting to the west to northwest late Monday. There is the
potential for high surf and possibly minor coastal flooding, but
with the recent deviation in low forecast track, confidence in the
where, how much, and timing is lower. Have issued a special
weather statement highlighting the potential with uncertainty
electing to allow later shifts to take a look at and consider the
29/00Z model suite solutions. Nonetheless, as the low moves inland
over the west coast and into the western interior, a slug of
moisture will bring either rain or rain/snow mix during the day,
transitioning to a rain/snow or snow mix at night from Sunday
evening through Tuesday. May see an inch or two in higher terrain
and possibly higher amounts in the upslope areas in the
southwestern Brooks Range.

Eastern and Central Interior...Leeside troughing north of the
Alaska Range will allow for gap winds to continue through Monday.
South gap winds between Isabel Pass and south of Delta Junction
will increase through this evening with gusts up to 60 mph
possible through late Sunday night before weakening. The wind
advisory for zone 226 looks to be in good shape. There is the
possibility of advisory level gusts to around 50 mph making their
way north into zone 223 and into Delta Junction. Will have to
monitor to see if one will be warranted. Mostly cloudy with a
chance of rain or snow across the area through the rest of the
weekend into early this week, except for the area immediately
north of the Alaska Range where downslope drying is expected to
limit precipitation potential Sunday.

North Slope and Brooks Range...Patchy stratus and fog along the
coast will become increase in areal coverage this evening and into
tonight. The latest AK-HRRR indicates that reduced visibility
below one mile is possible after midnight tonight between Nuiqsut
and Wainwright. Should see fog dissipate Sunday morning with
mostly cloudy skies persisting into at least the middle of next
week. Chances for snow along the western North Slope Sunday night,
then over the rest of the North Slope Monday morning. The Brooks
Range will see precipitation continuing for the west and
developing over the east tonight. May see between 2 to 4 inches of
snow through Monday morning, especially over the eastern Brooks
Range.

Coastal Hazard Potential Days 3 and 4...Potential continues to
increase for high surf and minor coastal flooding for Scammon Bay
and Cape Romanzof, the lower Yukon Delta as well as the northern
shore of St Lawrence Island late Sunday night and through the day
Monday. Current surf guidance indicates water levels rising to 5
to 6 feet above mean low low water levels or 3 to 4 feet above
High Astronomical Tide levels as gusty west to northwest winds
develop in these areas as a deep low moves inland over the Yukon
Delta coast during the day Monday. There remains considerable
uncertainty on the track of the low at this time. Small deviations
in the track of the storm will produce significant differences in
where the highest surf conditions will occur. A track of a
hundred miles further north would significantly increase the
potential for high surf and minor coastal flooding to eastern
Norton Sound. Continue to monitor for additonal updates.

&&

.FIRE WEATHER...Near Red Flag conditions will continue through Sunday
near the Alaska Range as gap winds develop later this afternoon
and evening. Expect winds gusting to around 55 mph with minimum relative
humidity values in the upper 20s through this evening and 30s
Sunday. Chances of rain and snow showers will increase through the
weekend as moisture moves northeast into the interior around a
low moving east out of the Bering Sea into Norton Sound.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Advisory for AKZ226.

Small Craft Advisory for PKZ210.
&&

LTH APR 18