Scientific Forecaster Discussion
Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
409 PM akst Wednesday Nov 25 2015
Main forecast concerns include precipitation type...amount...and
associated hazards across parts of the central and eastern
interior. Elsewhere across western Alaska...active winter weather
will continue to diminish. Overall there is decent agreement among
the 25/12z deterministic models...regarding the synoptic
features...however there are some differences regarding the
placement and timing of precipitation across the central and
eastern interior associated with surface stationary front and
upper level shortwave prognosticated to move over the Alaska Range and
eastern interior tonight.
Aloft...currently...an upper level ridge extends from the northern
Pacific north into far eastern Alaska and the Yukon territory.
This ridge will shift slowly east with time. To the west...a
broad upper level trough over the Bering with a 498 dam low over
eastern Siberia and another 504 dam low 200 miles south of Shemya
Island. This trough will gradually shift east and over Mainland
Alaska into the weekend. Meanwhile...south to southwest flow in
between these features will persist...pumping moisture originating
from the northern Pacific over central and eastern Mainland
Alaska through Friday. A shortwave embedded in this flow will
travel northeast today and arrive over the Alaska Range/southern
interior by this evening and then north over the eastern interior
Surface...a 996 mb low located 120 miles west of Point Hope will
weaken in place through Thursday...with the associated front
draped along the Arctic coast shifting north of the coast and
dissipating. A 991 mb low 400 miles south of Kodiak...with a
trough extending north over the Tanana Valley. This low will move
north to near Iliamna Lake as a 990 mb low Thursday
afternoon...with the associated trough extending northeast over
the middle Tanana Valley and upper Yukon River Valley.
Central and eastern interior...active winter weather continues
across much of the area. Ongoing winter weather hazards include
several winter storm warnings for zones 221...223...225 and 226
and a pair of winter weather advisories for zones 220 and 222 for
snow and freezing rain. Southwest flow aloft continues to pump
moisture into the area...allowing for heavy snow to continue in
the central and eastern Alaska Range with an additional foot or
more of snow accumulation expected through tomorrow. Additionally
there have been reports of treacherous driving conditions and Road
closures in this area. So will keep the winter storm warnings for
zones 221...225 and 226 going as is. For zone 223...made the
decision to keep the warning going instead of replacing it with a
Winter Weather Advisory...since snow is expected to redevelop late
this evening north of Quartz Lake with a high likelihood of
freezing rain. The pair of winter weather advisories look good
with the only change being including the entire zone of 220 into
In regards to freezing potential over the interior...there were
reports of light freezing rain earlier...mainly in the Alaska
Range and at Eielson AFB. NAM bufr soundings for the Fairbanks
area shows that most of the atmospheric profile below
freezing...with a shallow pocket of near 0c temperatures above
the surface this evening...with more warming tomorrow. Models
have changed somewhat to the extent and degree of warming above
the surface with the recent run...being a bit cooler than it was.
However...will keep the mention of freezing rain in The Hazards
and forecast. Nonetheless...it will be a winter mess out there
tonight and tomorrow.
Western Alaska...the Winter Weather Advisory for zone 227
continues as heavy snow and freezing rain is expected to continue
overnight into tomorrow. At Kivalina...winds have been favorable
along the coast for high surf and latest web cam images from
there show high surf conditions with slush being pushed
onshore...thus a high surf advisory was issued earlier today.
Elsewhere...fairly quiet weather compared to that of
recently...expecting only isolated to scattered showers over the
next few days. However...chances for precipitation will increase
this weekend as a low moves east along Aleutian island chain and
then north into southwest Alaska.
North Slope...fairly quiet weather is expected over the next few
days. Mostly cloudy skies with isolated to scattered snow showers.
Winds have weakened and are expected to remain below 20 miles per hour...so
no blowing snow concerns over the next few days.
Coastal hazard potential days 3 and 4...none
high surf advisory for akz207.
Winter Storm Warning for akz221-akz223-akz225-akz226.
Winter Weather Advisory for akz220-akz222-akz227.
Heavy freezing spray warning for pkz210-pkz220-pkz225.
Small Craft Advisory for pkz210-pkz220-pkz225.
Brisk Wind Advisory for pkz230.
Lth Nov 15