Scientific Forecaster Discussion
Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
247 am akdt Wednesday Jul 29 2015
Weak upper level ridging over the interior and southern West
Coast areas will persist through Thursday...ridging will then
gradually build from the west through the weekend with 500 mb
heights climbing to 100-150 meters above climatological normals.
Daytime high temperatures in the eastern interior will be above
normal over the weekend and into early next week...with near
normal temperatures expected elsewhere south of the Brooks range.
A moist and unstable air mass will persist over most of the
interior today...and over the southern and eastern interior
Friday. Showers and isolated thunderstorms are expected in
these areas. By Friday...instability will be limited to the
Alaska Range and in areas of the upper Yukon valley and fortymile
country near the alcan border as the upper level ridging builds
in...resulting in a drier and more stable air mass. Little or no
convection is expected in the interior Saturday as the drier and
more stable air mass expands eastward.
A weak surface thermal trough extending from the interior
Seward Peninsula to Eagle will be replaced by weak high
pressure ridging by Friday.
Over the Arctic region...upper low centers near 84n/155w and
77n/133w will merge into a single center 600 miles north of
deadhorse by late Wednesday night which will then move on a wobbly
cyclonic path to 500 miles north of Barter Island by late Saturday
night. The outer fringe of the cyclonic circulation around the
low will remain over the Arctic coast through Friday night...and
over the central and eastern Arctic coast Saturday. A 1000 mb low
near 77n/133w will move to near 80n/170w by Thursday evening and
to 400 miles north of deadhorse by late Friday night...weakening
to 1004 mb. A 1006 mb low will develop 100 miles south of wrangel
island Thursday evening...and move to near Barrow by Friday evening.
The low will then open up into a trough moving eastward to the
Canadian Beaufort Sea and northern Yukon territory by Saturday
morning. This low will bring rain to northwest Alaska Friday...rain
will spread eastward across the Arctic slope Friday night and
Saturday. Another period of rain will be possible over northwest
Alaska Saturday as another system emerges from the russian Arctic
Areas of fog along the Arctic coast through this morning
with onshore surface wind flow.
Coastal hazard potential days 3 and 4...none
isolated thunderstorms over much of the interior this
afternoon and evening...and over the southern and eastern
interior Thursday afternoon and evening. Gradual
warming and drying trend from the west Thursday into the
weekend as high pressure ridging builds in from the west.
Rf Jul 15