Scientific Forecaster Discussion
Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
1216 PM akdt Sat Aug 30 2014
A deep upper low...around 510 dam at 500 mb...is centered about
300 nm north northwest of Barrow. The low will remain nearly
stationary through early Tuesday morning...then move on a wobbly
course to about 100 nm north of Demarcation Point by Thursday evening.
A west to northwest flow will predominate over northern Alaska
through the end of next week...with a series of short wave troughs
moving eastward across the forecast area.
A rather weak short wave trough extending southward from the
northwest coast of Alaska will move eastward...to near the
alcan border then northwestward into the low center by sun
evening. Only isolated showers are expected with this short wave.
Over the North Slope...precipitation type will likely be mixed
rain and snow showers at lower elevations and mainly snow showers
in the Brooks range. Over the interior...precipitation type is
expected to be rain showers...but could be mixed with snow at pass
level in the Alaska Range.
The next short wave trough will be stronger and be accompanied
by a strong surface front. This short wave will arrive in
northwest Alaska and the northern West Coast late Sun night...
moving eastward into the Yukon territory by late Monday night.
The surface front will move eastward to extend from Demarcation
Point southwestward to near Dall Point by Monday evening. By late
Tuesday night the front will extend from around 100 miles north of
Eagle to just south of McGrath. Precipitation with this front will
begin over northwest Alaska and the West Coast from northern
Norton Sound northward Sun night. Precipitation will spread across
the western and central interior Monday...and to most of the Alaska
Range and eastern interior Monday night. Significant precipitation
amounts are expected with this short wave and weather front. Over
the the northern parts of the central interior...western
interior...northwest Alaska...and the central and northern parts
of the West Coast...event rainfall totals are expected to be
mainly 0.25 to 0.5 inches with local higher amounts up to 1 inch.
The heaviest rainfall totals...1 to 2 inches...are expected to be
over Denali..zone 226 west of the Richardson Highway...southern
zone 221...and the middle Tanana Valley during the 24 hour period
from 4 PM Tuesday to 4 PM Wednesday. Another 0.25 to 0.5 inch is expected in
these areas between 4 PM Wednesday and 4 PM Thursday...with local amounts to
0.75 inch possible in the Alaska Range.
Another strong short wave trough will follow...sweeping across
northwest Alaska and the West Coast Tuesday afternoon and evening...
moving east to the alcan border by Wednesday. More precipitation is
expected with this feature...but amounts are expected to
be less than those associated with the preceding short wave and
At the surface...a 992 mb low centered 300 miles north northwest
of Barrow will wobble around with little net movement through
early Tuesday morning. A secondary 991 mb low will develop near
Barrow Monday morning then move northeastward and merge into the
northern low center Monday night. By late Tuesday night...model solutions
differ on movement the low center out of the Arctic towards the
northern Alaska coast...but northwest winds 25-35 knots are possible
on the coast from Barrow westward Tuesday night. Strong west winds
may develop east of Barrow Wednesday as the low moves east.
Coastal hazard potential days 3 and 4...
elevated surf possible Monday night through Tuesday on the coast from
Barrow westward with west to northwest winds 15-25 knots. Potential
for high surf in this area Tuesday night through Wednesday...but there
is some uncertainty in timing. European model (ecmwf) brings the low center
faster...and farther westward...than the GFS...and moves the
low out eastward across the Beaufort Sea faster as well.
rainfall amounts of 1 to 2 inches expected in zone 222...zone
225...and western zone 226 between Tuesday afternoon and Wednesday
afternoon. These rainfall amounts would produce significant rises
on the Salcha...chena...and Chatanika rivers and their smaller
tributaries. Flooding could be possible on small streams draining
out of steep terrain in zones 225 and western zone 226.
frost advisory for akz222.
Rf Aug 14