955
FXAK69 PAFG 071220
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
420 AM AKDT Tue May 7 2024

.SYNOPSIS...
Unsettled conditions continue across much of northern Alaska the
next several days as a series of disturbances push across the
state. These disturbances will bring a mix of rain and snow.
Highest snow accumulations expected in the Brooks Range and in the
Fortymile Country where 2 to 4 inches are possible. Temperatures
trend upwards the next several days. A Flood Watch remains in
effect for the Yukon River at Circle.

&&

.DISCUSSION...
Synoptic Analysis and Forecast...
Aloft, at 500 mb, a longwave trough extends south from the pole
across much of mainland Alaska and into the Gulf of Alaska. A
weakening upper level low in the northern Gulf of Alaska moves
onshore this morning between Homer and Yakutat, lifting north
northwest along the AlCan border to be between Eagle and Fort
Yukon by early Wednesday morning. Another piece of energy rounding
the base of the trough today moves across the northern Gulf of
Alaska tonight, joining the first shortwave Wednesday morning. The
shortwave continues northwest across the Interior Wednesday to be
over the Western Brooks Range by Thursday morning and the
northwest Arctic coast by Friday morning. As this wave moves
north, ridging over the Yukon and Northwest Territories gets
shunted north over the Arctic waters. Further west, a closed upper
level low north of St Lawrence Island this morning dives south to
be between St Matthew Island and the Pribilofs by Wednesday
morning and the Alaska Peninsula by Thursday morning. This low
weakens Thursday into an open wave that lifts northeast along the
northern Gulf of Alaska coast through Thursday night and then
pushes north across the Interior Friday

At the surface, a 1026 mb high centered 500 NM north of Prudhoe
Bay moves northeast to be 250 NM northwest of Banks Island by
this afternoon, continuing northeast into the high Arctic through
Thursday. A 1000 mb low near Dawson City weakens as it moves
northwest to be near Venetie this afternoon with a trough
extending southwest to Galena to Crooked Creek. By Wednesday
morning troughing extends from a 1002 mb low near Inuvik southwest
to Manley Hot Springs to Aniak. The low near Inuvik lifts north
to be east of Liverpool Bay Northwest Territories by Wednesday
afternoon with troughing extending southwest to Eagle to Ruby to
Scammon Bay. By Thursday morning troughing extends from a 1008 mb
low near Kotzebue Sound southwest to offshore the Y-K Delta coast
and from the low east to Fairbanks. By Friday the low near
Kotzebue Sound has moved little with troughing extending east to
Bettles to a 1006 mb low near Dawson City. A weak trough near the
Gulf of Anadyr this morning moves south today developing into a
1005 mb low 150 NM southwest of St Matthew Island moving across
the Pribilofs Wednesday morning and to the Alaska Peninsula by
Thursday morning.

Models... The 07/00Z models initialized well against the 00Z
RAOBS and are in good agreement with the overall synoptic pattern.
After the past few nights, models are in good agreement with the
strength and track of the upper level low moving south across the
Bering Sea, additionally models are in much better agreement with
the shortwave moving across the Interior Wednesday and Thursday
and the shortwave/low that moves north across the Yukon and
Northwest Territories. At the surface there are some differences,
most notably in the westward extent of precipitation today over
the Eastern Interior. The ECMWF and the NAM to an extent bring the
precip furthest west, while the GFS and hi-res solutions keep the
precip further east over the Fortymile Country to the Brooks
Range. Leaned towards the GFS and hi-res solutions to keep the
highest pops further east and then blended in low end chance pops
further west towards the Middle Tanana Valley to account for
uncertainty.

North Slope and Brooks Range...
Areas of fog and stratus persist along the Arctic coast this
morning. The gradient off the northwest Arctic has relaxed today
with lighter winds prevailing. East to northeast winds of less
than 15 mph are expected through Wednesday. Wednesday night and
Thursday southerly winds of 10 to 20 mph develop in the eastern
Brooks Range. Gradient tightens over the northwest Arctic coast
late Wednesday into Thursday with a low near Kotzebue Sound,
resulting in northwest winds of 15 to 25 mph. A series of
disturbances moving across the Brooks Range through Friday
continue snow changes. Highest snowfall amounts expected in the
eastern Brooks Range. 1 to 2 inches of snow expected today and
tonight with an additional 2 to 4 inches expected Wednesday
through Thursday night. Along the coast, snow accumulation will be
lighter at 1 to 2 inches from today through Thursday night.
Temperatures trend upwards the next few days with highs for most
areas in the 20s.

West Coast and Western Interior...
The gradient off the northwest Arctic has relaxed today with
northeast winds of 10 to 15 mph prevailing from Point Hope
through the Bering Strait to near St Lawrence Island. Expect winds
in the 15 to 25 mph range in this area Wednesday and Thursday.
Elsewhere, winds will be less than 15 mph. General troughing aloft
and energy moving through the trough will continue to support
rain and snow showers through the week. The best precip chances
today and Wednesday will be south of Galena and in the Brooks
Range, where up to 2 inches of snow accumulation is possible.
Today trend upwards beginning today.

Central and Eastern Interior...
Precip chances continue today as another disturbance moves across
the Interior, bringing more snow, rain, and a rain-snow mix. The
best precip chances will be across the Eastern Interior, in
particular the Fortymile Country north to the Brooks Range. This
will bring 2 to 4 inches of snow to higher elevations an along the
Steese Highway north of Fairbanks. For valley locations including
Fairbanks mostly rain is expected but there could be a change
over to snow Tuesday evening. Weak southerly gap flow is ongoing
in the Alaska Range passes and is expected to continue through the
work week, increasing Wednesday night and Thursday, especially
over the eastern Alaska Range, where a Wind Advisory may be needed
Wednesday night into Thursday morning. Temperatures begin to
trend upwards today.

Extended Forecast Days 4-7...Deterministic and ensemble guidance
continue to indicate persistent broad upper level troughing over
much of mainland Alaska, the Bering Sea and the Gulf of Alaska
through the extended forecast. Guidance also suggests periodic
upper ridging in Canada pushing into the Eastern Interior. This
pattern supports scattered shower activity across northern Alaska
and energy moves through the trough. Temperatures across the
central and eastern Interior will largely be influenced on how far
east the trough axis moves and the southerly flow.

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

&&

.FIRE WEATHER...
A series of upper level disturbances will lift northwest across
the Interior through the end of the work supporting showers each
day. Warming trend ensues today. Minimum relative humidity values
largely remain above 25 percent today. Slightly lower minimum
relative humidity values expected Wednesday afternoon from the
Middle Tanana Valley east to the Alcan border. Winds generally
less than 15 mph. Weak southerly gap flow in the Alaska Range
passes continues through the week, increasing Wednesday night,
especially over the eastern Alaska Range. At this time it looks
like the strongest winds will be late Wednesday night and early
Thursday morning, so not anticipating Red Flag conditions at this
time.

&&

.HYDROLOGY...
As of late Monday, not much change has been reported and the Yukon
River breakup front is roughly 30 miles upstream of Circle, near
Coal Creek. There is a 20 mile run of dense ice above the breakup
front. Residents of Circle should be aware that the breakup front
is approaching. No overbank flooding has been reported yet.
However as the breakup front moves downstream, it is likely that
small jams may form and release, leading to fluctuating water
levels and potential minor or moderate flooding. A large run of
ice passed by Eagle Monday with a sharp rise in water levels
indicated at the river gage and through social media posts. This
high water and heavy ice run is expected to make it down to the
ice jam above Circle this morning.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Flood Watch for AKZ833.
PK...Heavy Freezing Spray Warning for PKZ801-851.
     Heavy Freezing Spray Warning for PKZ802-806-850.
     Heavy Freezing Spray Warning for PKZ803.
     Heavy Freezing Spray Warning for PKZ804.
     Heavy Freezing Spray Warning for PKZ805.
     Small Craft Advisory for PKZ806-810.
     Brisk Wind Advisory for PKZ807-811-817-854-856>858.
     Heavy Freezing Spray Warning for PKZ810-816.
     Small Craft Advisory for PKZ851.
&&

$$