High Wind in Alaska, November 28, 2023

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
646 AM AKST Tue Nov 28 2023

.SYNOPSIS...
A warm southerly flow pattern over Northern Alaska will persist
through Thu with temperatures remaining well above normal most
areas. There will be periods of snow over the West Coast, Western
Interior and Northern Interior through Wed, while the SE Interior
will be under dry southerly chinook winds this afternoon into
Wed, and the North Slope will be under dry southerly chinook
winds late tonight into Wed. Conditions will cool towards normal
late this week.

A storm west of the Bering Strait is causing south winds 20 to 30
mph along capes of the West Coast and over St Lawrence Island that
will slowly weaken through tonight. This is causing snow showers
over the West Coast from Seward Pen north and west that will
diminish from the south today. This is also causing sea levels 2-3
ft above normal and elevate surf along the West Coast this
morning that will decrease through the day today.

A storm in Bristol Bay will move north over the Southwest Interior
this afternoon and then into the Northwest Interior tonight and
weaken over NW AK on Wed. This will cause moderate to heavy snow
north into the SW Interior this afternoon, moving over the Western
Interior late this afternoon into this evening, and then over the
NW Interior late tonight. Expect 2-4 inches of snow in about a
6hr period of time with this feature in most areas, but could see
6-7 inches in the Nulato Hills and near Kaltag.

This storm will cause southeast winds 15 mph gusting to 25 mph
over the SW Interior this afternoon and over the Western Interior
tonight. This will also cause south winds gusting to 70 mph over
the Alaska Range this afternoon through Wed morning, and
southeast winds gusting to 50 mph near Delta Junction this
afternoon through Wed AM. As the storm moves north it will cause
south winds gusting to 40 mph over the Brooks Range from midnight
tonight through Wed afternoon.

Aloft...
The long wave pattern consists of a deep trough stretching from
the North Pole south over the Bering Sea and Eastern Russia with a
ridge over Western Canada and Eastern Alaska. This is causing a
southerly flow pattern with a series of short wave troughs moving
NE and digging into the ridge through the week and eventually
pulling the long wave east over Alaska by the end of the week.
This has set up a warm pattern for the next several days with
cooling towards normal by the end of the week.

Surface...
A 976 mb low 200 NM west of St Lawrence Island will weaken in
place to 990 mb by 3am Wed, and to 997 mb by 3am Thu. A weatehr
front stretching SE from this low is causing light snow over the
West Coast and Interior north of the Seward Pen and Fairbanks that
will diminishin from the south today.

A 988 mb low 300 NM north of Utqiagvik will move to 300 NM north
of Barter Island as a 1006 mb low by 3am Wed and then continue
east. This will cause patchy light snow and fog along the Arctic
Coast today and tonight.

A 992 mb low 200 NM west of Point Hope will weaken slowly in
place.

A low in Bristol Bay will move to 100 NM southeast of Kotzebue as
a 996 mb low by 3am Wed and to near Utqiagvik as a 1003 mb low by
3am Thu. This will bring moderate to heavy snow over Western
Interior today and tonight, and strong winds to the AK Range this
afternoon into Wed AM, and to the Brooks Range late tonight into
Wed.

&&

.DISCUSSION...
At 00Z, models initialize well aloft. Models show similar
solutions aloft through 3pm Wed, then start to show differences
in short wave strength and timing that increase through time. The
long wave patterns remain similar into the weekend. Will use a
blend of models for features aloft through Thu.

850 mb temperatures range from -8 to -10 with warming to near -4
in the chinook shadow of the Alaska Range this afternoon into
tonight and then remaining like that into Thu.

With precipitation, models show similar areal coverage and amounts
through Thu. Will use a blend of models for pops and amounts.
Highlights are:
Light snow Fairbanks east diminishing from the SW today with less
than 1 inch additional snow. Light snow along the West Coast from
the Seward Pen north diminishing from the south with less than an
additional inch. Moderate to heavy snow spreading into north into
the SW Interior this afternoon, moving over the Western Interior
late this afternoon into this evening, and then over the NW
Interior late tonight. Expect 2-4 inches of snow in about a 6hr
period of time with this feature in most areas, but could see 6-7
inches in the Nulato Hills and near Kaltag.

At the surface at 06Z, the NAM verifies 3 mb too strong in the low
in the Gulf of Anadyr while other models do well on that feature,
and all models verify 2-3 mb too weak on the low near Cold Bay.
The NAM and ECMWF deepen the Cold Bay low more than the GFS this
morning, and keep the low deeper as it moves north over the
Western Interior this afternoon and tonight. Since this surface
low will likely remain deeper than models indicate, favor the
NAM/ECMWF solutions at the surface. Will use the NAM for surface
winds, particularly along the AK Range where this deeper low will
cause stronger winds as shown by the NAM. Highlights are:
South winds 15-25 kt over the Northern Bering Sea decreasing this
afternoon. Southeast winds 15 gust 25 mph over the SW Interior
this afternoon and over the Western Interior tonight. South winds
gusting to 70 mph over the Alaska Range this afternoon through Wed
morning. Southeast winds gusting to 50 mph near Delta Junction
this afternoon through Wed AM. South winds gusting to 40 mph over
the Brooks Range from midnight tonight through Wed afternoon.

Coastal Hazard Potential Days 3 and 4...
Water levels along the West Coast are 2-3 feet above normal, but
stronger winds and elevate surf remain west of Nome. Winds
generally offshore Fri into Sat not significant coastal issued Fri
into Sat.

&&

.PREV DISCUSSION... /issued 234 PM AKST Mon Nov 27 2023/

SYNOPSIS...

Elevated water levels of 2 to 3 feet above normal high tide remain
expected into Tuesday along the West Coast. Moderate to potentially
heavy snowfall is expected in the West Interior Tuesday late morning
to evening. Very strong southerly winds, gusting 60 to 80 mph,
within and immediately north of the Alaska Range are possible
Tuesday afternoon to late Tuesday night. Blowing snow may occur on
the Parks Highway within the Alaska Range Tuesday afternoon and
evening. Temperatures returning to near-normal remain expected
starting Saturday night and Sunday daytime.

DISCUSSION...

Upper levels, analysis and model discussion...

A closed low set up over the north-central Bering Sea this morning
and remains around 972 mb this afternoon. Models have continued to
struggle with the placement of a shortwave currently over Unalaska
as it lifts northward tonight over Bristol Bay and enters the
Alaskan Peninsula tomorrow morning. There was a notable shift
eastward in the overnight 06Z and 12Z deterministic guidance in the
main band of possible heavy snowfall for the West Interior. This
trend was reversed somewhat with the 18Z guidance as the main
band shifted slight back further westward. This ongoing trend
keeps high uncertainty in the actual placement of the main band of
heavy snowfall, but moderate confidence in moderate snowfall within
the Winter Storm Watches. Models have trended even further up in
expected wind speeds for Tuesday afternoon and overnight along the
and immediately north of the Alaska Range. Gap winds of 70 to 80
mph are entirely possible Tuesday afternoon to early overnight.

Central and Eastern Interior...

A cold front moving northward this afternoon and tonight brings very
light snowfall to the area. The more impactful time period is likely
to be Tuesday afternoon through Tuesday night over and north of the
Alaska Range when a shortwave passing from south to north over the
West Interior increases the pressure gradient along the Range.
Southerly gap winds are enhanced as a low-level jet will already
be in place from 50-60 knots per high res model guidance. The
western AK Range and northward High Wind Watch remains in effect,
with an expansion now into the the eastern Range and encompassing
Delta Junction. While winds in Delta Junction and immediate
surrounding areas likely will not reach Warning criteria, there is
still fair confidence for the Watch with a possible upgrade to an
Advisory down the road. Gap winds between Isabella Pass and north
to Fort Greely could gust to 80 mph tomorrow night. The strongest
winds are expected from early Tuesday evening to early Tuesday
night. As the shortwave lifts into the western Arctic by Wednesday
morning, winds drop off fairly quickly into mid-day so the Watch
currently ends in the eastern zones at 6 AM Wed. Blowing snow may
occur along the Parks Highway between Summit and Denali Airports
Tuesday evening, which could drop visibility down to 1 mile from
downstream snow being blown in from the west, even if winds are
only 25 to 35 mph along the Highway. A Special Weather Statement
has been issued for these blowing snow conditions. Temperatures
five to ten degrees above normal persist into mid- week.

West Coast and Western Interior...

A front lifting northward this afternoon is located from Kotzebue
Sound to the central Alaska Range and bringing scattered light
rain/snow mix to the immediate coastline of the West Coast and snow
to the West Interior. A few locations in the West Interior may see a
quick inch or two of snowfall tonight into Tuesday morning, but
impactful snowfall is not expected for the next 18 hours. A quick
moving shortwave lifts northward from the Alaska Peninsula Tuesday
early morning. This will be a time when a quick 3 to 6 inches,
locally up to 7 inches, may fall for the Lower Kuskowim Valley,
including west of McGrath, and the central and lower Yukon River
valleys throughout the West Interior. Winter Storm Watches remain
in effect for the Lower/Central Yukon River zones and was expanded
into the Kuskowin Valley zone, including McGrath, for that potential
of moderate to locally heavy snowfall by Tuesday night. Winds
also quickly increase and may gust to 45 mph in McGrath, to create
blowing snow and limited visibility concerns. Strong winds are
also possible in the southwestern Alaska Range Tuesday late morning
to Tuesday night, with a High Wind Watch remaining in effect.

Ongoing strong southerly winds 25 to 35 knots are expected to
continue to build water levels against the southwest Seward
Peninsula Coast, Bering Strait Coastlines, the south side of St
Lawrence Island and possibly the Yukon Delta. Ensemble guidance
still shows the most likely elevated water levels from 2 to 3 feet
lasting into Tuesday. Those water levels through Tuesday afternoon
recede Tuesday night and return to near-normal by Wednesday evening.

North Slope and Brooks Range...

Ongoing freezing fog along the eastern half of the Arctic Ocean
tapers this evening as onshore to shore parallel flow veers offshore
across the entire Coast tonight. The next few days will feature
multiple chances of light snowfall. The incoming cold front from the
south first brings very light snowfall to the central and western
North Slope region tonight. South to southwest flow continues into
tomorrow ahead of an advancing shortwave through the West Interior.
The western Brooks Range and northwest Arctic Coast may see a few
inches of snowfall late Tuesday night into early Wednesday morning.
As a low deepens over the West Interior Thursday morning, another
weak shortwave rotates through the mean easterly trough rotates
northwestward and could bring another chance of very light snow.

Extended Forecast Days 4-7...

Still warm, southerly air advects into the Interior Thursday PM and
Friday. This will lead to temperatures remaining 5 to 10 degrees
above normal. Easterly off-shore flow over the West Coast leads to
drier conditions, except the Yukon Delta where a low pressure over
the southeast Bering keeps shore-parallel moisture in the southwest
coastlines. Colder air slides into the Interior Saturday night from
east to west and then spreads at or slightly below normal
temperatures areawide into early next week. Expect at or below zero
temperatures beginning Saturday night and carrying forward.

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

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Winter Storm Watch for AKZ829.
     Winter Storm Watch for AKZ830-852.
     High Wind Watch for AKZ837-849.
     High Wind Watch for AKZ847-851.
PK...Small Craft Advisory for PKZ806-807-850-856.
     Small Craft Advisory for PKZ811.
     Brisk Wind Advisory for PKZ812.
     Brisk Wind Advisory for PKZ813.
     Gale Warning for PKZ851.
     Small Craft Advisory for PKZ853-858.
&&