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Northern Alaska forecast discussion 
National Weather Service Fairbanks Alaska
201 PM akdt Friday Jul 22 2016

Discussion...
Hydro related issues across interior Alaska stemming from recent
heavy rainfall and the potential for more rainfall are the main
forecast concerns for this forecast period. Latest 22/12z models
are in good agreement throughout the forecast period.

Westerly flow over Alaska has weakened and will continue to break
down today as an upper low moves over southwestern Alaska. This
upper low will continue to push southeast and into the Gulf of
Alaska tonight. Meanwhile, another upper low will drop south over
the western Arctic coast tonight and south over the western
interior and southwest through late Sunday night. By Sunday night,
pattern will have evolved into a large scale trough stretching
from MacKenzie Bay and eastern Beaufort Sea coast southwest to
Bristol Bay. This pattern will continue to keep an unsettled, wet,
showery pattern over most of northern Alaska.

At the surface, a weak broad trough stretching from the chukotsk
peninsula across Alaska and over the Yukon territory will slowly
shift south over northern Alaska through the weekend. A 1000 mb
low will develop over the Kenai Peninsula this evening then track
southeast along the coast. High pressure centered 400 miles north
of Barrow over the Arctic Ocean will gradually shift east through
early next week.

Central and eastern interior....a large scale trough at the
surface and aloft over northern Alaska will help to maintain the
showery, cloudy, unsettled pattern over the central and eastern
interior. Heaviest rainfall amounts through the weekend are
expected along the eastern Alaska Range, where up to 1 inch of
rainfall and numerous to widespread showers are forecast. Will
have to monitor river drainages that flow north into the upper
Tanana Valley, the Delta, Nabesna, Johnson, Robertson, and
gerstile. Isolated to scattered rain showers will continue over
the rest of the area through the weekend with forecast rainfall
amounts ranging from 0.10 to 0.40 inch.

West Coast and western interior...a wet unsettled weather pattern
will continue for locations from the Seward Peninsula south
through the weekend. Periods of rain will develop over the Bering
Strait and Saint Lawrence Island this evening and spread southeast
over the Yukon Delta and lower Yukon valley Saturday morning and
continue through Saturday night. From 0.25 to 0.40 inch is
expected to fall over these areas through Sunday evening.

Arctic coast and Brooks range...areas of fog from Barrow east and
north over the Beaufort Sea coast is quite evident on the 1847z
image of the NASA sport daytime microphysics product. Fog is
expected to hang in along the coast tonight. Northerly flow will
become easterly tonight as the surface high pressure over the
Arctic Ocean slides east and will increase over the Beaufort Sea
coast Sunday. Isolated to scattered rain showers are expected over
the eastern Brooks range Saturday and Sunday. Isolated
thunderstorms over the Yukon Flats and eastern Brooks range are
expected this evening and over the western and central interior
Saturday.

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

&&

Fire weather...wet conditions will continue to keep fire weather
concerns to a minimum through early next week. Relative humidity
values will continue to be high and above 40 percent with
excellent overnight recovery. Isolated thunderstorms over the
Yukon Flats and eastern Brooks range are expected this evening and
over the western and central interior Saturday.



&&

Hydrology...Flood Advisory for the chena river upstream of Moose
Creek dam continues, see latest statement for up to date
information. Most river and streams are bankfull with the chena
river at Two Rivers cresting earlier this morning and other
locations upstream still slowly rising with a crest expected
tonight. Latest model run paints the heaviest precipitation over
the eastern Alaska Range over the weekend, so will have to keep a
close watch on the rivers draining north into the upper Tanana
Valley, the Delta, Nabesna, Johnson, Robertson, and gerstile. In
western Denali National Park, water levels on streams in rivers
will likely remain near bankfull stage today due to the saturated
ground and recent rainfall.



&&

Afg watches/warnings/advisories...
Small Craft Advisory for pkz210-pkz220-pkz225-pkz230. &&

$$

Lth Jul 16

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