966
FXAK69 PAFG 191330
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
430 AM AKST Sun Jan 19 2025

.SYNOPSIS...

Another potentially impactful West Coast Storm is possible
Tuesday and Wednesday. An arctic front will set up from the Y-K
Delta to the Kobuk Valley. Where the front sets up there will be
heavy snowfall underneath it. There is still a lot of uncertainty
on the exact location of the narrow arctic front, as well as the
snow amounts. A shortwave trough will be moving through the
interior Sunday night bringing light snow accumulations to much of
the interior. There is more confidence that we will see a full
pattern change by the end of the week with ridging breaking down
over the Eastern portion of the state and being replaced with
troughing.

&&

.DISCUSSION...

Key Weather Messages:

Central and Eastern Interior...

- Temperatures are beginning to warm in the Interior this morning.
  The highs throughout the week will be in the 20s.

- Southerly gap winds will continue through Isabell Pass the
  remainder of the day today. There could be gusts up to 60 mph.
  A Tanana Valley Jet will continue through tomorrow night with
  Delta Junction gusting up to 40 mph and Nenana gusting up to 35
  mph.

- Snowfall will return to the Interior tonight. Accumulations
  will remain light as there isn`t a lot of moisture to be had in
  the atmosphere. Here in Fairbanks we should expect up to an inch
  of snowfall. The Richardson Highway south of Trims Camp
  however, will see some heavier snowfall with accumulations of 7
  to 10 inches through tonight.

West Coast and Western Interior...

- Light rain continues to fall across the West Coast this morning.
  Another weak low is moving into the Y-K Delta and will bring
  cooler temperatures back transitioning the rain to snow. The
  Southern Seward Peninsula could see an additional 3 to 5 inches
  of snow through tonight.

- Monday there will be some brief calm conditions as another low
  paired with a strong arctic front moves into the Bering by
  Monday evening. This arctic front will potentially bring a
  narrow band of long duration heavy snowfall from the Y-K Delta
  to the Kobuk Valley. The exact location of the band is still
  uncertain, however currently we are looking at it to be from
  Hooper Bay to Unalakleet then to Ambler with it`s western edge
  of the band being somewhere in between Elim and Nome. Snow
  totals could be up to a foot in some spots depending on snow
  ratios.

- The system on Tuesday looks to northeasterly wind gusts up to 35
  mph from the Seward Peninsula to the Y-K Delta. We could see
  significant visibility restrictions in areas that are receiving
  the heaviest snow as well as gusty winds.

- After this next system moves out of the area Wednesday morning
  there will be another system Thursday and Friday. This system
  looks to be bring a quick shot of snow the West Coast. The
  weekend looks to be quiet as weak high pressure builds in the
  Bering Sea.

North Slope and Brooks Range...

- Chinook flow will continue today bringing near record warm
  temperatures from the Brooks Range to the Arctic Coast.
  Temperatures are currently above freezing across the Arctic
  Plains and along the coast east of Wainwright.

- Point Hope will see additional snow accumulations up to 3".
  Southerly winds up to 45 mph could create visibility
  restrictions down to a 1/2 mile at at times through today.

- Monday evening there will be some falling snow as well as
  southerly gap winds through the Brooks Range passes up to 40
  mph. Blowing snow could create visibility restrictions through
  the overnight and

Forecast Analysis and Confidence...

A 990 mb low is moving north across the Y-K Delta near Kipnuk
currently. This low will bring another round of moisture advection
and cold air advection. The light rain in the Southern Seward
Peninsula and Kotzebue Sound will transition back to snow by
midday today. With this next push of moisture there could be
another 6 inches of snow due to continued uplsope flow. The
gradient through Alaska Range will slowly weaken today as the
1040 mb high in the Northwest Territory of Canada begins to weaken
and move southeast.

Monday night there will be an arctic low that moves east from
Wrangell Island that will have an arctic front draped to the
southwest. This front will catch up to an inverted trough that is
associated with a 990 mb low south of St. George Island. There
will be rapid frontogenesis along this boundary creating a very
narrow band of heavy snowfall. Now determining snow amounts will
be a bit tricky, because where there is cold air advection on the
western portion of the boundary the ratios will be 15 to 1 or even
as high as 20 to 1. On the eastern portion of the boundary where
there is still sub tropical air being advected into the region the
ratios would be 8 to 1 or 10 to 1. With a narrow band of
precipitation it will make nailing exact amounts difficult. The
exact placement of the boundary is also uncertain at this time.
The GFS and ECMWF are complete opposites on where they place the
band of heavy snow. The GFS has it from St. Lawrence Island to
Nome and the Kotzebue while the ECMWF has it from Hooper Bay to
Koyuk to Ambler. We are trending to the ECMWF solution as the
ECMWF/GFS ensemble support that solution as well as the Nam. If we
average the ratios in the whole band and work with 13 to 1 snow,
snow totals will be 8 to 12" of snow along this boundary. Some
areas would receive less due to lower ratios and some could get
more. The 12z model runs will give us more confidence on either
solutions as this is a relatively new solution that was given.



Extended Forecast Days 4-8...

Next weekend we will see the ridging over the Eastern Interior
fully break down as a strong polar low moves across the high
arctic and an arctic front goes through the Interior. We have seen
2 days of continuity with the ECMWF/GFS Ensembles as well as their
deterministic models showing this arctic front coming through the
interior, so our confidence of this occuring is going up. This
front would bring some gusty winds to the Interior as well as
snow. All of the models are showing southwesterly flow going into
the Interior, which is our preferred flow to get heavier snowfall
here in Fairbanks. There is still a lot of uncertainty with snow
totals and timing. This pattern will have a lot of moving parts
which could effect the amount of snow we could see in the
Interior. We will continue to monitor and hopefully get a clearer
picture in the coming days.

Coastal Hazard Potential Days 3 and 4...None.


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Winter Weather Advisory for AKZ801.
     Wind Advisory for AKZ849.
     Winter Weather Advisory for AKZ850.
PK...Brisk Wind Advisory for PKZ803.
     Brisk Wind Advisory for PKZ804-807-808.
     Brisk Wind Advisory for PKZ805.
     Brisk Wind Advisory for PKZ806-814.
     Brisk Wind Advisory for PKZ809-852-855.
     Gale Warning for PKZ810.
     Gale Warning for PKZ811-857.
     Brisk Wind Advisory for PKZ812-858.
     Brisk Wind Advisory for PKZ816-851.
     Brisk Wind Advisory for PKZ817-854.
     Gale Warning for PKZ856.
&&

$$

Dennis