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Northern Alaska forecast discussion...corrected
National Weather Service Fairbanks Alaska
410 PM akdt Wed Aug 23 2017

Synopsis...
aloft...
the long wave trough over Mainland Alaska will persist through the
weekend, and possibly into next week. This will cause temperatures
through the weekend of below normal over the North Slope, West
Coast and western interior, with slightly above normal
temperatures in eastern interior.

Weak short waves will drop from the high Arctic down the West
Coast of Alaska into the long wave trough, then deepen in the Gulf
of Alaska and swing north over the interior through sun. This
will cause periods of showers over the interior through the
weekend, while the West Coast is fairly dry and the North Slope
has periods of rain and snow.

A strong short wave trough will move north over the eastern
interior on Fri causing isolated thunderstorms.

A second short wave will move north over the southeast interior
Sat combined with a surface occluded front. This will bring
scattered showers and isolated thunderstorms on Sat to the
southeast interior.

Surface...
high pressure north of the Arctic coast to the northern Bering Sea
will build over the eastern Bering Sea through Thu then persisting
into the weekend. This will cause north winds to increase over the
West Coast tonight and persist into Fri and possibly Sat. Expect
20-30 kt strongest over western CAPES. This will also cause fog to
continue along the Arctic coast and north facing shores of the
West Coast.

An Arctic front from Barrow to the Yukon Delta will move to Barter
Island to Anaktuvuk Pass to the Yukon Delta by 4pm Thu, quasi
stationary into Fri and then to along the Brooks range crest Sat.
Snow levels will fall to 2000-3000 ft along the Arctic front, with
levels falling to sfc-2000 feet north of the Brooks range Thu
night through Sat. Not much snow expected through Thu, but could
see up to 4 inches above 3000 feet in the Brooks range Fri-Sat.

A 994 mb low in the southeast Bering will move to Bristol Bay as a
992 mb low Thu, and into the northwest Gulf of Alaska Fri. An
occluded front stretching out ahead of this low over Bristol Bay
will move to Bethel to McGrath by 4am Thu with a warm front from
McGrath to Livengood. By 4pm Thu the occluded front will remain
from Bethel to Anvik with the warm front moving to Anvik to Arctic
Village by 4pm Thu. The warm front will edge north over the
Arctic front Thu night and Fri, then persist into Sat. Rain with
the front has spread north to Anvik and McGrath now and will
spread north with the warm front tonight and Thu. Expect 25.To .50
inch of rain in zone 215 216 and 227 tonight through Thu with
this front. Precipitation will become progressively lighter and
more spotty in the eastern interior with the front. Precipitation
will become more likely Fri and Sat over the Brooks range as the
warm front over runs the Arctic front. This could drop up to 4
inches of snow above 3000 feet in the Brooks range Fri-Sat. Expect
most of the snow to melt after hitting the ground from 2000-3000
feet so only a few inches accumulation at those elevations.
Little if any accumulation below 2000 feet.

A Lee side trough will develop north of the Alaska Range tonight
as south flow aloft increases ahead of the occluded front. This
will cause south winds to gust to 45 mph through Alaska Range
passes from from late tonight through Thu night. Winds will
decrease Fri as flow aloft weakens and the Lee side trough
weakens.

&&

Discussion...
models initialize well and similar with most features through Sat.
Differ some on details of precipitation amounts and locations.
Prefer the GFS precipitation which shows the feature now in the southeast
Bering bringing highs amounts into SW interior the next few days.
Starting Sunday models diverge sharply on details with even the
long wave positions differing next week. This leads to low
confidence for the forecast for next week.



Coastal hazard potential days 3 and 4...none.

&&

Fire weather...
some drying over eastern interior the next several days but rh
remaining above 30%. Strong gusty winds through Alaska Range
passes developing tonight and continuing Thu.
Isolated thunderstorms in the eastern interior Fri and sun.

&&

Hydrology...
rivers falling across northern Alaska.
Expect .25 to .50 inch in the southwest interior tonight and Thu.

&&

Afg watches/warnings/advisories...
Small Craft Advisory for pkz210-pkz220-pkz225.

&&

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