Area Forecast Discussion
Issued by NWS Fairbanks, AK

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
000
FXAK69 PAFG 222320
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
320 PM AKDT Sat Jul 22 2017

.DISCUSSION...
Active weather pattern over northern Alaska continues

The 12z model suite initialized well against the 12z surface
analysis and vitrified well against the 18z surface analysis.
The models continue to struggle with both the run to run
continuity as well as the model families differences. Spread
continues to be large in the short range and continues into both
the mid range and long range.

Model depictions of the track and strength of an early season low
moving northeast out of Siberia into the southern Chukchi Sea
continue to show surface pressure differences of over 4 mb by the
48 hours and position differences of over 200 nm at the same time
range. These small differences in track and strength and therefore
wind fields will have significant impacts on the when and where
and to what extent high surf and coastal erosion will impact the
west coast and northwest coasts through Monday.

A 993 mb low currently over Siberia will track northeast and
enter the Chukchi Sea around 200 nm southeast of Wrangel Island as
a 990 mb low Sunday morning and will be located 150 nm northwest
of Point Lay as a 990 mb low Sunday evening. The low continues to
move northeast to be located approximately 50 nm north of Barrow
by Monday morning as a 994 mb low. The continues on a northeast
track and weakens to 995 mb over approximately 200 nm north of
Prudhoe Bay Monday evening.

The track of this low will bring persistent southwest to west
winds over a large area of the west coast north of the lower YK
Delta and the north slope coast west of Barrow. The favorable
wind direction and event duration will produce elevated surf and
high surf along much of the west, southwest and south facing
coasts of northern Alaska. A high Surf advisory has been issued
for a portion of the coast in eastern Norton Sound between Cape
Darby and Unalakleet. Offshore waves of over 6 feet, and storm
surge values of between 4 and 5 feet combined with persistent
southwest winds of 30 mph will produce high surf conditions along
this portion of the coast. Special Weather Statement outlining
the potential for elevated surf with surge values in the 3 to 4
foot range from near Nome to Cape Darby and from near Unalakleet
to the lower YK Delta Coast has been issued. A Special Weather
Statement has also been issued for the coastline in and near
Kotzebue Sound where 1 to 2 foot storm surge values are expected
and as well as north of Cape Krusenstern where a 2 to 3 foot storm
surge is expected to develop Sunday afternoon and continuing into
Monday. The highest storm surge values are expected to develop
Sunday afternoon and continue into Monday.

The ongoing High Surf Advisory on the north slope near Barrow
remains on track with high surf noted on webcams and photos. The
high surf conditions with current surge values in the 1 foot
range above normal tides are expected to improve this evening as
the strong westerly winds diminish. Surge models continue to
indicate surge values increasing to 1 to 2 feet above normal tides
again Sunday afternoon and continuing into Monday, however wind
direction will switch to the south or southeast later tonight and
will remain offshore through late Sunday night or Monday morning
and will limit wave runup on the coast. The wind will shift back
to the northwest Monday morning and combined with still hi tide
level will present a window for another High Surf event. Continue
to monitor.

Deep and moist southwest flow from the northern pacific is
forecast to move northeast ahead of a front moving ahead of the
low moving out of Siberia into the Chukchi Sea. Heavy rains are
expected to develop over the western Brooks Range Sunday with 1 to
2 inches of rain possible in the heaviest areas through Monday
evening. Will need to closely monitor this area for rapid rises
on small streams and rivers. Generally less than 1 inch of rain is
expected through Monday night over the west coast and western
interior. The soaking rains continue to move east into the
central interior Sunday night and Monday with generally one half
to one inch expected. The deep westerly flow will enhance rainfall
totals in the western Alaska Range where steep terrain will
increase the risk of rapid rises on small streams and rivers.

The ongoing rain event in the eastern Brooks Range will be added
to with this next storm as westerly flow on Monday generates
another one half to one inch of rain over already rain soaked
terrain. Will need to monitor rises in small streams and rivers in
this area as well as the western Alaska Range.


Coastal Hazard Potential Days 3 and 4...None.

&&

.FIRE WEATHER...None.

&&

.HYDROLOGY...
Continue to monitor the Eastern Brooks Range and Eastern North
Slope as ongoing rain event 24 hour totals have added another one
half to one inch of rain on top of the rain that fell Thursday
night and Friday. Expect another one half to one inch with inbound
storm through Monday.

Continue to monitor the Western Brooks Range with expected
rainfall of 1 to 2 inches through Monday evening.

Continue to monitor Western Alaska Range with expected rainfall
totals of one half to one inch through Monday evening.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
High Wind Watch for AKZ205.

High Surf Advisory for AKZ202-AKZ212.

Small Craft Advisory for PKZ200-PKZ210-PKZ215-PKZ220-PKZ225-
PKZ235-PKZ240-PKZ245.
&&

$$

CCC JUL 17


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.