321
FXAK69 PAFG 251210 CCA
AFDAFG

Northern Alaska Forecast Discussion National Weather Service
Fairbanks AK 406 AM AKDT Wed Sep 25 2024

.SYNOPSIS...
Weather remains quiet and mostly unimpactful across Northern
Alaska. An arctic trough will keep areas of light snow over the N
Slope and Arctic through Thursday. Showers with snow levels
between 1500 and 2500 feet will continue across the Interior. A
mix of showers and mostly clear skies are expected across the West
Coast.


&&

.DISCUSSION...

Analysis and Model Discussion...
The 25/00z model suite initialized well with observations aloft
and at the surface. Models are in good agreement through Saturday
morning.

Global models are running a bit too strong on winds on the West
Coast. We will use a blend of the NBM and high resolution models
for the winds, and a general blend of models with minimal hand
edits for other elements.

Aloft at 500 mb, an elongated north/south oriented upper level low
lies over the West Coast with northerly flow to the west over the
Bering Strait. Weak southerly flow is in place east of the low
center, which is near Kotzebue. The low will migrate slowly to the
west through the forecast period, with a ridge building over the
central and eastern Interior Friday and Saturday. At the surface,
gradients will remain mostly light. A NE/SW gradient across the West
Coast will keep north/northeast winds of 15 to 20 mph in place there
through much of the forecast period. A north/south gradient across
the Brooks Range producing winds gusting to 25 mph through Anaktuvuk
and Atigun Passes will weaken tonight. High pressure building over
the Copper Basin will bring southerly gap winds through Alaska Range
passes beginning late Friday night and early Saturday morning.

Central and Eastern Interior...Quiet weather persists with highs
near normal and lows above normal under cloudy skies. These
conditions will persist through Friday. Patchy fog is expected
this morning from Minchumina to McGrath and from Delta Junction
east along the Alaska Highway. Shower coverage will decrease each
day through Friday. Showers will be most numerous today and
tonight over the Yukon Flats, tomorrow over the Fortymile Country,
and Friday over the Upper Koyukuk Valley. Snow levels will be
mainly between 1500 and 2500 feet, though a bit higher from
Fairbanks southeast to the Alcan Border. Winds will be light
except through Alaska Range passes beginning Friday. Highs will be
in the 40s with lows in the 30s.

Anecdote: The latest first freeze of the season on record at
Fairbanks International Airport is September 27, 1974. Cloudy
skies this week will make Saturday September 28th the first day
where a freeze may be likely. Models are in good agreement that
skies will be clear Saturday morning with a mid level dry slot
moving north over the Alaska Range beneath the building ridge of
high pressure, though gap winds through Alaska Range passes may
be strong enough to produce modest adiabatic heating. At this
time, a freeze appears likely on Saturday morning, but is far from
certain.

North Slope and Brooks Range...Snow showers are expected in the
Brooks Range and north across the Arctic Plain today and tonight
with an inch or less of accumulation. Along the coast, expect
clouds with some areas of fog and low stratus to continue. A few
light snow showers are possible mainly east of Deadhorse. Winds will
be 15 mph or less. Highs will be in the 30s, except in the 20s over
Brooks Range passes. Lows will be in the 20s and lower 30s.

West Coast and Western Interior...Mostly sunny conditions along
the coast today will transition to mostly cloudy overnight. North
winds will remain around 15 mph through Thursday morning before
increasing to around 25 mph through the Bering Strait. In the
interior, rain and snow showers are expected today and will
diminish in coverage overnight tonight. Snow levels will be near
the surface. Highs everywhere will be in the low 40s with lows in
the upper 20s and low 30s, except in the mid 30s at St. Lawrence
Island.

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

Extended Forecast For Days 4 through 7...Forecast models are in
agreement that the extended forecast period beginning on Saturday
will begin with a ridge in place and seasonably warm and dry
conditions over the Central and Eastern Interior and North Slope,
with showers and cooler conditions on the West Coast. These
conditions will likely pesist until Tuesday when models show a
low in the Bering Sea bringing a front to the West Coast. A
potentially impactful low may follow in the Thursday/Friday
timeframe, however there is still a lot of uncertainty on location
and timing. The Interior looks to be much drier and cooler beginning
on Saturday.

A note on the first significant snow in the Fairbanks area:
Ensembles show a large spread, but generally agree that the first
measurable snowfall won`t be before the October 4-7 timeframe. GFS
ensemble members all indicate some amount of measurable snowfall
in Fairbanks by October 7. The ECMWF is less enthusiastic, but
probabilities for measurable snow increase beginning around
October 6. The average first measurable snow in Fairbanks is
October 2 and the average first snowfall of one inch or greater is
October 10.

&&

.HYDROLOGY...No concerns.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...None.
PK...Small Craft Advisory for PKZ851.
&&

$$

CHRIEST