Scientific Forecaster Discussion
Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
227 am akst Wed Dec 7 2016
Models...good run to run continuity in the short term and in a
general way trend to similar solutions through the extended
periods. Initialized well against the 07/06z surface analysis.
Temperature guidance is still lacking as models bounce all over.
Will be using a blend of the solutions for all elements except
temperatures where a more hands on approach will be used.
Aloft...at 500 hpa...a ridge extends from the North Pacific over
the central Aleutians to the Gulf of Anadyr the northwest to a
556 dam center over the northwest coast this morning. The ridge
remains stationary through Thursday morning as a 558 dam high
center separates from the ridge and moves over the western
Arctic. By Friday morning the ridging over the central Bering Sea
remains stationary with ridging extending northwest across the
chukotsk peninsula to the 558 dam center 300 nm north of Point
Barrow. The pattern takes more of an Omega signature as a 529 dam
low develops over Bristol Bay Thursday evening, then moves south,
with yet another 529 dam low developing over Bristol Bay in its
wake. By Saturday morning the ridging over the Arctic takes more
of a west to east orientation as the troughing over Bristol Bay
pushes west over the Pribilof Islands. At 850 hpa...the Fairbanks
upper air sounding had 17.2 celsius below at 3 PM yesterday. This
was around 4 degrees cooler than the 3 am observation. Models
currently indicate temperatures will remain about the same through
Thursday then a slow warming trend through the weekend.
Surface...not much change since yesterday, a 1057 mb high center
sits over the northwest territories with ridging extending west
and south over the forecast area, and will persist into the
weekend. A 1012 mb low that was over Kodiak Island yesterday has
moved into the western Gulf of Alaska and will remain relatively
stationary, then drift southwest before eventually merging with a
low in the northeast Pacific. The local gusty winds that occur are
really impacting the temperature forecasts, models continue to
show some compacted pressure gradients in some of the drainages,
and winds are gusting over the summits around the interior to
around 30 mph. There are also some indications that the Tanana
Valley jet may kick in around Delta Junction and that will also
impact temperatures around Delta Junction.
Arctic coast and Brooks range...a pesky patch of stratus is easily
identified on the npp-viirs sport nighttime microphysics product
at 07/0018z. It extends from about 200 nm north of Point Barrow to
Point Barrow, then east over the coast to Harrison Bay. The patch
is about 100 nm wide in some places and has been lingering in the
area for the past 24 hours or so impacting the aviation forecasts.
Another small patch is hanging around Nuiqsut impacting that
site. Otherwise mostly clear skies will continue. Winds generally
east to southeast at 5 to 15 mph. Low temperatures will range from
around 20 below along the coast to around 35 below in some of the
coastal plains locations, while highs will range from around 10
below to around 30 below.
West Coast and western interior...quiet the next few days. Mostly
clear conditions continue. Winds along the coast northeast to
southeast at 5 to 15 mph, inland winds will generally be less than
10 mph. Temperatures warmer in the windier locations. Coldest
temperatures will be in the middle Yukon valley with lows around
25 below Thursday morning. Temperatures across the area will be
slowly warming starting Thursday afternoon.
Central and eastern interior...the forecast challenge will be the
winds. If they pick up temperatures will be warmer in the windy
locations. Areas with light or no winds will generally stay cold.
Will forecast worst scenario, but temperatures in some areas could
be 20 degrees warmer than forecast again today. The coldest
temperatures will continue to be in the upper Yukon Flats.
Temperatures across the area will be warmer starting Friday. Some
stratus has moved into the upper Tanana Valley and fortymile
country south of a line from Eagle to Chicken. Northway has been
reporting light snow most of the last 24 hours and that will
continue into the afternoon before tapering back to flurries.
Accumulation will be less than an inch.
Coastal hazard potential days 3 and 4...none.
Heavy freezing spray warning for pkz210-pkz220-pkz225.
Brisk Wind Advisory for pkz245.
Sdb Dec 16