Scientific Forecaster Discussion
Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
550 am akdt Thursday Jul 24 2014
aloft...long wave trough from Barrow to Cordova will move to
Prudhoe Bay to Cordova 4pm Sat with a closed low near Fairbanks.
Several short wave troughs will move from western Alaska and far
east Russia into the central interior during this time and help
form the closed low which develops in the trough.
Surface...cold front from near Barter Island to Tanana to 50
miles north of Unalakleet to the southern Bering Strait...moving
to inuvik Canada to Eagle to Delta Junction to Talkeetna to Anvik
to Nome 10 am Friday...then the portion over western Alaska will
drift east to lie from Denali park to Cape Lisburne through 4pm
Models...NAM and European model (ecmwf) solution aloft are favored over GFS in that
they develop the closed low near Fairbanks Sat afternoon. In
medium term there is fair agreement between the European model (ecmwf) and the GFS
in maintaining the trough over eastern Alaska while expanding the
Bering Sea ridge into the western interior.
North Slope...the cold advection behind the front is producing
significant snow over the Brooks range above 2000 feet which will
taper off from the east on Friday. Amounts up to 5 inches expected
Western Alaska...areas of rain behind the cold front...will mix
with or turn to snow above 2000 feet over the south slopes of the
Brooks range today for up to 2 inches of accumulation. Precipitation
ending from the west late today and this evening. A short wave
trough moving in from Russia will bring period of light rain to
the Bering Strait and Saint Lawrence Island Friday and to Nome Friday
night and Norton Sound Sat.
Central and eastern interior...as the short wave trough moves in
from western Alaska...areas of rain near and behind the cold
front will increase in coverage and spread to the east through the
day. Up to two thirds of an inch of rain is expected over the
chena basin through this evening. Some thunderstorms possible
over the upper Koyukuk valley and southeastern Brooks range this
afternoon if enough heating allows destabilization at low levels.
Another area for isolated thunderstorms is the upper Tanana
Valley where some unstable air remains ahead of the cold front.
As the main upper trough begins to drift east tonight...the area
of persistent rain will shift east of Fort Yukon and Fairbanks
where up to 1 inch of rain is expected over the forty mile country
and Delta area...and 1 to 2 inches over the central Alaska Range
from the Richardson Highway to Denali park through Friday night.
Over the southeastern Brooks range expect snow level to drop to
3000 feet tonight with accumulations of several inches into Friday
Coastal hazard potential days 3 and 4...none.
Fire weather...the wet and cool pattern across the interior will
keep humidities high into the weekend.
Hydrology...rivers over the eastern interior will rise into the
weekend in response to the rain...for now no flooding is
expected...but will need to monitor. Small streams in the central
Alaska Range will especially run high. The rain over the
southeastern Brooks range did not accumulate Wednesday night to
the extent was thought earlier...so streams there will only rise
somewhat after some rain today and this evening.
Small Craft Advisory for pkz215-pkz245.
Jl Jul 14