Weather Service Report


642 
FXAK69 PAFG 152132
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
132 PM AKDT Sun Jul 15 2018

.DISCUSSION...
An active and progressive pattern will continue across Northern 
Alaska through the week. Model solutions remain similar through 
late Tuesday in regards to the overall synoptic pattern, however
solutions diverge significantly from Wednesday on, especially on
the track and strength of a low pressure system developing near
Wrangel Island that will impact the western North Slope and
Chukchi Sea coastline north of Cape Krusenstern with strong winds,
and high surf Tuesday and Wednesday. Another low will push onto 
the west coast and western interior late in the week with strong
winds and heavy rain. 

The 12z model suite initialized well against the 12z surface
analysis and verified well against the 18z surface analysis. Model
spread is limited in the short range but begins to develop
considerable spread by Tuesday especially on the track and
strength of a deep low that forms near Wrangel Island Tuesday and
tracks east just north of the North Slope on Wednesday. 
Considerable spread exists among the models on the track and 
strength of a low that moves out of Siberia, through the Bering 
Strait and onto the west coast, the western Brooks Range and the 
western interior Thursday night and Friday. 

Aloft at 500 mb, a 549 dam low over the Kenai Peninsula anchors a
long wave trough centered over Alaska today. The trough will
continue over Alaska with new shortwaves diving south over Siberia
into the trough and will provide an active weather pattern over
northern Alaska through the week.

On the North Slope the focus turns to a 986 mb low expected to
develop over northern Siberia and move into the Chukchi Sea near
Wrangel Island Tuesday evening. Gale Force southwest winds ahead 
of the low will develop north of the Bering Strait and Southern 
Chukchi Sea Tuesday afternoon and evening and will produce high 
surf along the Chukchi Sea north of Cape Krusenstern and along the
west coast of the North Slope. Limited fetch and parallel winds 
along the coast from Cape Lisburne northward to near Wainwright 
where the icepack edge is located will initially limit high surf
potential initially, but as the wind shifts to the west and 
northwest Wednesday will need to monitor potential for high surf. 
Model guidance continues to indicate surge levels around 2 feet 
above normal tides Tuesday night and Wednesday. Continue to 
monitor.

A low moving through the Bering Strait will bring periods of rain
over the West Coast tonight. Scattered showers and isolated
thunderstorms are expected over the western interior tonight and
again on Monday. Another low will move east out Bering Strait on
Thursday and will produce another round of rain perhaps heavy rain over
the West Coast north of the Seward Peninsula, the western Brooks
Range and the northern portions of the western interior Thursday
night and Friday.

Scattered showers and isolated thunderstorms are expected over the
central and eastern interior tonight and again Monday afternoon 
and evening. 

Coastal Hazard Potential Days 3 and 4...
Models continue to indicate a rapidly deepening low moving into 
the southern Chukchi Sea Tuesday evening and into Wednesday, 
however there are significant differences on timing, track and 
strength of this early season storm. Small differences in the 
track and strength will strongly influence what coastlines will 
receive the strongest impacts. At this time strong southwest winds
are expected to develop north of the Bering Strait on Tuesday 
afternoon and continue into Wednesday as the low rapidly develops 
near Wrangle Island. High Surf will likely develop Tuesday 
afternoon and continue into Wednesday along south and west facing 
coastlines between Cape Krusenstern and Point Hope. Elevated surf 
may produce minor shoreline erosion and push debris high onto the 
beach. Boats and other property near the high tide line may be 
damages.

Strong southwest winds will also develop ahead of the low along 
the western North Slope from Cape Lisburne to Point Barrow 
Tuesday night and will continue into Wednesday. Winds will become 
west to northwest Wednesday afternoon and may push surf and debris
above the high tide line along the coast from Wainwright south. 
The icepack remains to the north of Wainwright and will likely 
erode to the northeast as strong southwest winds and 12 foot seas 
impact the icepack edge. Models continue to indicate a somewhat 
fast moving storm system with the limited southwest fetch however
a slight change in storm track would produce a longer northwest 
fetch and would result in waves pushing further onshore. Continue 
to monitor.

&&

.FIRE WEATHER...
Minimal fire weather concerns today through Tuesday as cool and 
unsettled weather will prevail as an upper level trough remains 
over central and western Alaska. Expect scattered showers and 
isolated thunderstorms over much of the eastern and and central 
interior while a low moving southwest out of the Bering Strait 
and into the western interior provides widespread wetting rains 
over most the western interior. A brief warm up is expected for 
midweek over the central and eastern interior Tuesday through 
Thursday. A weather system has the potential to bring widespread 
wetting rainfall to the west coast and western interior again by 
late next week; however, at this point, there is a lot of 
uncertainty in the exact details of this.

&&

.HYDROLOGY...
No major issues anticipated over the next few days. A weather system
late next week has the potential to bring heavy precipitation to 
a rather wide area, especially over the west coast, western
interior and the western Brooks Range. Differences between model
solutions remain in the timing and details of this system. Given 
the potential widespread nature of the expected precipitation, 
there may be some rises to smaller streams in western Alaska as 
this system moves through. We will have to continue to monitor 
this situation as it evolves.

&&

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

$$

CCC JUL 18

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Western Regional Climate Center, wrcc@dri.edu