Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Northern Alaska forecast discussion 
National Weather Service Fairbanks Alaska
123 PM akst Friday Feb 27 2015

Discussion...

Models...have been very consistent all week in development of the
weather front in the Bering Sea that will be moving across the
state the next 36 to 48 hours. The 12z GFS and European model (ecmwf) runs
initialized well against the 18z surface with very minor pressure
differences. Will use a blend of the models to nudge the current
gridded database...but will bump most of the probability of precipitation up using the
sref so we have categorical probability of precipitation with the system. Precipitation
numbers look pretty consistent with around one half inch so most
areas will see 3 to 7 inches of snow.

Aloft...at 500 hpa...ridge over the central part of the state
extends from a high near Hawaii. The ridge will be flattened out
as a weak shortwave moves across the top of it this evening. A
second...much stronger...shortwave associated with a 499 dam low
will move to the West Coast by early Saturday morning...then from
Wainwright to Tanana to Lime Village by Saturday afternoon as the
low falls 497 dam as it moves to the high Arctic. The low
continues to strengthen as it moves to 78n 160w in the high Arctic
and the shortwave moves to lie from deadhorse to Fort Yukon to
McCarthy by late Saturday evening...then exits the state early
Sunday morning. Ridging will build in pretty rapidly behind the
shortwave as heights climb from around 534 dam Saturday evening to
around 550 dam Sunday morning. The ridge will continue to rotate
over the area through Tuesday stalling over the Yukon territory as
a long wave trough anchored by a 532 dam low over the western
Alaska Peninsula digs in over the West Coast. At 850 hpa...cold
air advection across the area as the ridge slides east.
Temperatures will fall 12 to 16 degrees celsius over the next 36
hours...then begin to warm Sunday and rise 12 to 16 degrees from
Sunday afternoon to late Monday...then become pretty steady
through the week. Winds kick up pretty good with the front to 40
to 50 kts a few hours either side of frontal passage.

Surface...1029 mb high over the interior will be pushed south and
east as a rapidly moving weather front moves east across the
state. The front will move to the West Coast early Saturday
morning as it lies from Point Hope to Nome to Kipnuk by around 3
am...then from Wainwright to Kotzebue to Marshall by 9am Saturday.
The front continues east to lie from Nuiqsut to Bettles to Tanana
to Lime Village by 3 PM...and then from Demarcation Point to Fort
Yukon to eielson to Palmer by 6 PM Saturday evening. The front
will continue east exiting the state early Sunday morning. A
fairly strong gradient will develop behind the front as a 1040 mb
high builds in rapidly behind it...winds will come down
significantly by middle day Sunday as the high pressure build over
the interior. Strong gradient will persist over the eastern Arctic
coast into Sunday evening. The high will continue to build as it
moves over the Arctic coast Sunday evening at 1045 mb...then
slides into the Yukon territory by Monday morning. Ridging will
persist over the central interior with Lee side troughing along
the north side of the Alaska and Brooks ranges.

Arctic coast and Brooks range...it is going to be a mess the next
24 to 48 hours as the front moves through the area. Models showing
around 20 celsius of cold air advection and that combined with
strong pressure gradient will produce some very significant
winds...especially over the northeast coast. Winds will pick up in
the west this evening and work across the Arctic. Initially winds
will be 10 to 20 miles per hour increasing to 25 to 40 miles per hour gusting around 50
miles per hour...that will be as strong as the wind gets west of
Nuiqsut...to the east of Nuiqsut the winds will continue to
increase as the gradient and cold air advection combine to push
winds to near hurricane force of 65 miles per hour gusting to 80 miles per hour. Winds
will begin to settle down Sunday morning as the front continues
east and the ridge of high pressure build over the area. Expect 3
to 7 inches of snow but most of that will be blown around into
drifts. Visibility will be very poor and white out conditions will
occur from Saturday evening through Sunday morning. Temperatures
will fall 20 to 30 degrees fahrenheit over the next couple days
then rebound up 10 to 20 degrees fairly rapidly Monday. Will
issue blizzard warnings for zones 203...204...and 206 mainly east
of the Dalton Highway. Winter weather advisories for mainly
blowing snow and strong winds for zones 201...202...and 205.

West Coast and western interior...snow showers moving over the
coast this evening associated with the first shortwave. Some areas
will see up to 2 inches of snow with this first shot. The next
shot will come with the front that gets to the coast Saturday
morning. This front will carry a little punch with it so expect 3
to 7 inches of snow over most of the areas as the front moves west
to east. The coastal areas will begin clearing by noon with
inland areas clearing in the afternoon and evening. Wind will not
be as strong out here as they will be on the Arctic coast and in
the interior as the cold air hangs back a little. Still expect
that many locations will see winds in the 30 to 40 miles per hour range.
Strong winds to 50 miles per hour can be expect in the Kotzebue Sound region
and the Bering Strait...but they should only last a few hours.
Temperatures will be on the roller coaster as they cool rapidly
behind the front then warm rapidly as the ridge of high pressure
moves to the east of the area by Monday afternoon. Will keep the
winter storm warnings up for 207...208...213...and 217. Will
issue winter weather advisories for zones 209 and 210 for near
blizzard conditions.

Central and eastern interior...mostly clear tonight with
increasing clouds Saturday. Conditions will deteriorate rapidly
Saturday afternoon and evening as the weather front marches
through the area. Winds increasing around Tanana by 10 am Saturday
with winds increasing fairly rapidly in the Fairbanks area in the
late afternoon and early evening. Winds trending down overnight
from the west. Strongest winds will be over the hills with gusts
to 50 miles per hour but expect winds in the valleys to gusts to around 40
miles per hour. Snowfall with the front will be in the 3 to 7 inch range for
most areas...but much of that snow on the hills will be blown
around into drifts. There will also be some drifting of snow in
the valleys. Temperatures will fall significantly Saturday
night...but look for them to rebound Monday. Will issue winter
weather advisories for zones 218...219...220...221...222...and
224.

Satellite...sport modis 27/2040z/npp viirs at 27/2012z 24 hour
and nighttime microphysics rgbs show the large area of stratus
moving around the ridge over the interior. A little harder to see
it on the nighttime microphysics...but using in combination with
the GOES MVFR/IFR/LIFR products and the GOES cloud phase product
it stands out really well.

&&

Afg watches/warnings/advisories...

Winter Storm Warning for akz207-akz208-akz213-akz217.

Blizzard Warning for akz203-akz204-akz206.

Winter Weather Advisory for akz201-akz202-akz205-akz218-akz219-
akz220-akz221-akz222.

Brisk Wind Advisory for pkz200-pkz210-pkz215-pkz220-pkz225-
pkz235.

&&

$$

Sdb Feb 15

National Weather Service Glossary of Abbreviations