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490
FXAK69 PAFG 212322
AFDAFG
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
222 PM AKST Tue Jan 21 2025
.SYNOPSIS...
A series of storms will impact the west coast through the week. A
strong front will set up over the west coast Tuesday into
Wednesday. A heavy band of snow will set up from the Seward Penn
to the Kobuk Valley. Winter Storm Warnings remain in effect for
these areas. A stronger storm will impact the west coast and
Northwest Alaska Thursday into Friday bringing high winds, heavy
snow, and some mixed precipitation south of the Seward Penn. This
system will also impact the Western north slope and Brooks Range
Friday into Saturday with high winds, snow and blowing snow.
The potential for heavy snow as well as possible mixed
precipitation over the Western and Central Interior this weekend,
then turning much colder towards the end of the month over much of
the area.
.DISCUSSION...
Key Weather Messages:
Central and Eastern Interior...
- Much warmer than normal temperatures continue this week with
highs mostly in the 20s before most areas reach the 30s on
Friday and over the weekend.
- Southerly gap winds through Isabel and Windy Passes will
continue to gust to 60 mph into Wednesday. Wind Advisories are
in effect.
- Areas of heavy rain and snow are expected beginning late
Thursday night and Friday morning, mainly west of Fairbanks.
Over a foot of snow possible for higher terrain locations along
the Dalton Highway and from Bettles west.
West Coast and Western Interior...
- A strong front will set up over the west coast Tuesday into
Wednesday. A heavy band of snow will set up from the Y-K Delta
to the Kobuk Valley. Winter Storm Warnings have been issued for
portions of the west coast, including the Seward Penn. Snow
totals could be up to a foot in some spots depending on snow
ratios. Winter Storm Warnings remain in effect for these areas.
- 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 late Wednesday,
there will be another weaker shortwave moving through the west
coast late Wed into Thursday, then a more impactful system late
Thursday into Friday. This system looks to be bring strong
winds and heavy snow initially, then mixed precipitation as it
moves northeast through Saturday. Gusts over 60 mph are possible
along the coast. Another foot of snow is possible along the
Nulato Hills, Seward Penn and Kobuk Valley.
North Slope and Brooks Range...
- Well above normal temperatures continue today from the Brooks
Range to the Arctic Coast. Expect temperatures mainly in the
20s, with colder air filtering back in from west to east through
Wednesday.
- Strong winds, snow and blowing snow will begin to develop over
the western north slope and Brooks Range on Friday as a strong
low and tight gradient swiftly moves through the area. The north
slope and Brooks range temps will bottom out on Sunday and
beyond as the strong cold front sweeps through the area over the
weekend.
Forecast Analysis and Confidence...
Upper level pattern shows an upper level low near Wrangel Island
will continue to track to the NE over the Arctic. Another upper
low will move into Bristol By on Tuesday and another shortwave
move through the west coast late Wednesday into Thursday. An upper
level low over E Russia will develop and be the main player for
the late Thursday Storm over the west coast. Southwestly flow
will set up over the west coast and Interior Thursday and into the
weekend as the main upper low tracks NE across the Arctic. This
will be a good set up for parts of the western Interior to see
several inches of snow.
A strong front will set up over the west coast Tuesday into
Wednesday. There will be rapid frontogenesis along this boundary
creating a very narrow band of heavy snowfall. Heavy band of snow
has shifted slightly to the west to include the Seward Penn. Have
upgraded the last of the watches to warnings. We are trending to
the ECMWF solution as the ECMWF/GFS ensemble support that solution
as well as the Nam. Snow totals will be 8 to 12" of snow along
this boundary. Models are still in some disagreement on the
the timing of the precip and precip type that will be moving
across the western Interior and Central Interior over the weekend.
Extended Forecast Days 4-8...
A major pattern shift is likely by the end of the week as flow
turns more southwesterly and a number of strong low pressure
systems enter the Bering Sea. The overall pattern is favorable to
bring an abundance of warm air and precipitation northward over
western Alaska and possibly into the central and eastern Interior.
Expect a strong storm with high winds across the West Coast on
late Thursday into Friday, with increasing chances for heavy
precipitation in the Interior late Friday through Sunday as well
as gusty winds over higher terrain of the Interior. Some areas
will see heavy snow and there could be mixed precipitation as well
over the Interior. There is still some model differences on
timing and amounts and precip type. Models indicate an increasing
probability for very cold temperatures early next week behind this
system.
Coastal Hazard Potential Days 3 and 4...Impactful storm will
produce near Storm-force winds offshore as well as possible water
moving over the ice or any open leads along the coastlines of the
Y-K Delta and Norton Sound and Northwest Alaska late Thursday into
Friday. Shorefast ice may be lifted, and minor flooding may occur
in areas where shorefast ice is lifted. There is a high amount of
uncertainty in terms of what the impacts of this storm will be
due to the track, time of year, and ice extent. Without ice in
place, this would be a major coastal storm. Given the extent of
the ice and thickness, impacts are expected to be minimal, so no
coastal flood products will be issued at this time. The Potential
for coastal impacts remains south of Hooper Bay and Nunivak
Island.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Wind Advisory for AKZ847-849.
Winter Storm Warning for AKZ813-816-819-822-823.
Winter Storm Warning for AKZ824>826-829-830.
PK...Heavy Freezing Spray Warning for PKZ801.
Small Craft Advisory for PKZ802.
Heavy Freezing Spray Warning for PKZ802-803.
Small Craft Advisory for PKZ803-804.
Heavy Freezing Spray Warning for PKZ804.
Gale Warning for PKZ805.
Brisk Wind Advisory for PKZ806-816-817-851-852.
Brisk Wind Advisory for PKZ807-856.
Brisk Wind Advisory for PKZ810-811.
Brisk Wind Advisory for PKZ812-853-858.
Brisk Wind Advisory for PKZ814.
Brisk Wind Advisory for PKZ815.
Brisk Wind Advisory for PKZ850.
Gale Warning for PKZ854.
Brisk Wind Advisory for PKZ857.
Brisk Wind Advisory for PKZ859.
Brisk Wind Advisory for PKZ861.
&&
$$
119
FXAK68 PAFC 220315
AFDAFC
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
615 PM AKST Tue Jan 21 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: This
afternoon through Friday afternoon)...
Active weather persists across Southcentral Alaska. A strong
front transits across the north Gulf coast through early tomorrow
morning, bringing gusty winds and moderate rain/snow. Several
weaker storms follow behind this front from Wednesday through
Thursday, leading to unsettled weather but nothing particularly
hazardous... though we`re keeping an eye on snow amounts for the
Homer Bluffs and Susitna Valley. By late Friday morning, a warm
and wet atmospheric river begins to move in, hinting at much more
impactful weather this weekend. For the front moving through
tonight, we are currently monitoring heavy snow in Turnagain Pass,
with snowfall rates of 1-2 inches per hour potentially leading to
lower visibilities through 9 PM. Please see the Winter Weather
Advisory for more information.
Diving into the details...strong winds and light to moderate
precipitation are the name of the game as a front lifts northwards
across the Gulf coast. The strongest gusts/peak winds so far have
been: 71 mph at Portage Lake, 68 mph at Whittier Access Road, 59
mph at Middleton Island, and 55 mph at both Cordova and Kodiak
Airport. Most of the precipitation has fallen along Eastern Kenai
Peninsula and the Kachemak Bay area, though Anchorage did pick up
a trace of snow/graupel earlier today. The front will gradually
weaken as it runs up against the coast, with winds diminishing by
late tonight.
Behind the front, south to southwesterly flow will usher in
cooler air. Weaker upper level shortwave troughs moving in behind
the front will help prolong precipitation along the coast, as well
as bring light precipitation to areas bordering Cook Inlet.
Expect a light band of rain/snow mix to move north across Western
Kenai Peninsula, Anchorage, and Mat-Su from late Wednesday morning
through Wednesday evening. Any precipitation that falls should be
light. There is some question of whether the air will be cold
enough to support all snow for these locations; have kept the
forecast precipitation type as rain/snow mix for now as the
coldest air looks to move in after this band of precipitation has
gone through. By Thursday morning, a chance for all but the Copper
River Basin and Kodiak Island to see another round of light snow
as a quick-moving shortwave transits west-to-east across
Southcentral.
We`ll be monitoring two areas with the Wednesday and Thursday
storms: the Homer Bluffs and northern Susitna Valley.
Southwesterly flow is favorable for higher snow amounts at these
locations due to enhancement from upslope flow along the terrain.
Susitna Valley could pick up a fair amount of snow in the coming
days as several rounds of precipitation move through. Ballpark
values are around a foot or more north of Talkeetna, though this
will be occurring over a long duration of light to moderate
snowfall rates. For the Homer Bluffs, models tend to underdo snow
amounts, especially in convective snow showers like the type we`ll
see on Wednesday. Snow amounts look higher for the Bluffs
Thursday, but we`re expecting temperatures to warm up ahead of
Friday`s atmospheric river, which could cut down overall snow
amounts. All told, confidence is low regarding the potential for
snow or blowing snow on the Bluffs, so that will bear watching.
-Chen
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA AND THE BERING
SEA/ALEUTIANS (Today through Friday afternoon)...
Currently, spotty showers are affecting the southwest mainland
due to the presence of a low over Bristol Bay. These showers are
mostly in the form of rain due to a warmer air mass in place
driven by southerly flow. The low will weaken as it moves onshore
later today and will break down into a trough as it moves
northeastward. On the backend of the weakening low, winds will
shift to a more westerly direction, allowing cold air from the
Bering to intrude and convert any lingering precipitation to snow
early Wednesday. This will be shortlived, however, as a weak ridge
pushes in from the west by Wednesday afternoon, diminishing
precipitation chances. Looking at the Bering, a Kamchatka low
swings in, bringing rainfall and high-end gale force winds to the
western Aleutians this afternoon. Cooler air behind the low will
allow for snow showers in the same area. This low will quickly
track eastward, bringing a burst of precipitation and gale force
winds to the Bering and Aleutians throughout Wednesday.
Following the previous low is a more compact North Pacific low
riding an atmospheric river. This low will push the prior low
onshore more quickly, allowing for some brief inland snow showers,
then rain showers as southerly flow drives a warmer airmass
inland by Thursday morning. Gale force winds will also affect
Bristol Bay and the Kuskokwim coast. The North Pacific low
mentioned before will rapidly move northwards into the Bering,
passing by the Pribilof Islands by Thursday afternoon. Heavy
precipitation mostly in the form of rain will accompany this low.
The more impactful feature, however, will be the winds. This low
will drive winds to storm force category, which will affect the
Eastern Aleutians and Alaska Peninsula from Nikolski to Cold Bay,
as well as the Pribilof Islands and Kuskokwim coast. The effects
on the Kuskokwim coast are notable because surge from this low
will drive waves up and could cause coastal flooding. Communities
such as Kwigillingok and Kongiganak could be affected. Due to this
threat, a Coastal Flood Watch has been issued for the Kuskokwim
Delta Coast. Water levels could rise 4 to 6 ft above the normal
highest tide line from Wednesday evening to Friday morning. As the
low tracks northward, winds will quickly diminish by Friday
afternoon. However, the atmospheric river will remain, and will
drive tons of moisture into the southwest mainland. This means
that moderate to heavy precipitation will affect a large swath of
the southwest mainland including Bethel, Dillingham, King Salmon,
and Iliamna through the end of the short term.
It doesn`t end there as a very cold air mass moves in from the
west. Temperatures will decrease in the Bering through Friday and
convective snow showers will affect the western and central
Aleutians, eventually reaching the Pribilofs by Friday afternoon.
The cold air will reach the Kuskokwim Delta region by this time as
well, transitioning rain into snow near Bethel. Looking a bit
ahead reveals that this cold air mass could drop temperatures
below zero in the mainland, especially in the northern regions.
Other implications are likely, so we will monitor as this event as
it draws closer.
-JAR
&&
.LONG TERM FORECAST (Days 4 through 7: Saturday through
Tuesday)...
Little change from previous discussion.
Strong winds, precipitation and unseasonably warm temperatures
will continue through Monday over much of Southern Alaska as a
frontal system moves across the region. A major change in the
weather pattern late Monday and into Tuesday will see Southerly
winds give way to a more northerly component across much of
Southern Alaska as an Arctic airmass dips southward into the lower
half of the state. Much lower temperatures are expected across
much of Southern Alaska by Tuesday.
A very strong longwave ridge along the U.S. and Canadian west
coast, coupled with a deep longwave trough with associated closed
low and frontal systems is expected to be moving up into the
northern Bering Sea and up into far northeastern Russia. Strong
pressure and temperature gradients between these two systems will
be very impressive even by Alaskan standards. The strong pressure
gradient setting up along this boundary, plus at least two
distinct stronger areas of low pressure that will move north along
it, will support strong southwest winds, initially over the
eastern Aleutians and Southwest. Stronger winds could also affect
parts of Southcentral on Sunday as the second low moves up from
the Pacific into Southwest. Heavy precipitation along the main
frontal zone is expected as deep moisture will help support rather
intense precipitation rates for much of Southwest and later
Southcentral compared to what is typically possible for late
January. Temperatures in many areas of Southwest close to sea
level will likely initially be warm enough for rain at lower
elevations, and this will likely also be the case as the front
shifts into Southcentral between Sunday and Monday. There could be
a transition over to snow across both Southwest and Southcentral
as cooler air begins to move in behind the front between Sunday
and Monday.
&&
.AVIATION...
PANC... The likelihood of wind shear from this morning through
late this evening remains. As a front moves through the Gulf
today, northerly winds change to a more northeasterly/easterly
direction mid-afternoon. Winds continue to shift southeast as
Turnagain Arm winds bend into Anchorage. Wind gusts will range
from 20 to 30 knots later this evening into Thursday. Otherwise,
VFR conditions expected.
&&
$$
918
FXAK67 PAJK 212307
AFDAJK
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
207 PM AKST Tue Jan 21 2025
.SHORT TERM...Another gale force front is upon us Tuesday evening
into early Wednesday. Satellite imagery shows the main front
entering the eastern gulf and the parent low located over the
western AK interior. The front tracks quickly over the region
bringing moderate precip, mainly over the south with QPF totals
near an inch to two inches, and elevated winds through the
morning. Temperatures remain steady or have a slight rise as the
front crosses over so majority of precip will fall as rain.
Unseasonable temps in the low 40s and mid 30s for Wednesday. The
rain-snow mix early on should only produce 1 to 2 inches at most,
with the exception of Haines, Skagway and their highways with
accumulations of 3 to possibly 4 inches. Residual showers for
Wednesday will be mostly rain. Coastal wind gusts with the front
in the 40 mph range while breezy inner channel wind gusts likely
getting to 30 mph. Models have been overall consistent so little
change made to the inherited forecast.
.LONG TERM.../Thursday into next week/...Minor changes to the
overall forecast, particularly in regards keeping the
precipitation out of the panhandle for the most part through the
weekend. Unfortunately, Yakutat is not included in the lack of
precipitation.
For Thursday and the weekend, a blocking pattern looks to set up,
with run to run consistency of the GEFS and ensemble Euro
settling on a 580 dam ridge. At the surface, this means a high
pressure, with approximately 80% chance of being above 1045 mb in
the gulf, unseasonable for this time of year. This will bring
clearing skies, downward motion aloft, and lighter winds for the
inner waters. The main source of uncertainty in regards to these
patterns is how long the ridge will stick around, which will
determine when precipitation returns. Upstream; however, has very
cold arctic air advecting down from the Arctic, which will assist
in both strong systems moving into the northern Gulf Coast, and
pushing the stream of moisture towards the NE Gulf Coast/Yakutat
area. It does indeed to look that the ridge will win over the cold
air advection moving in from the north for at least another day.
Main moisture transport, with significant spread, has the general
consensus that Yakutat will see heavy rain by late in the weekend.
Beyond the weekend; however, cold air will indeed push the ridge
to the east, moving SE AK back into an active pattern, but this
time with much colder temperatures aloft compared to now. Sufficed
to say, a pattern change is in the works.
&&
.AVIATION...As the next front approaches, CIGs and VIS will
lower due to mainly rain. Wind speeds will increase in association
with the front. So expecting wind shear to develop for coastal
areas and parts of the southern panhandle.
Lowest flying conditions will be seen during the overnight into
early morning hours Wednesday, around 6z to 18z (9PM Tues to 9AM
Wednesday). This is the window where the the front will begin to
lower conditions along the coast to the backside of the front
exiting the panhandle. After that window, the entire panhandle
should start to see improvement.
Wind shear starts to ramp up earlier. The HREF has probabilities of
wind shear >20 knots over 50% along the coast beginning later this
afternoon (3-5pm). Going into the overnight, the probabilities
spread inland and increase to over 70% for much of the area. Around
10z (2AM Wed), the probabilities start to decrease for the coast
with those much lower probabilities (<20% chance) spreading inland
overnight. Most areas will be done with wind shear by 18z (9AM)
Wednesday.
&&
.MARINE...Eastern gulf gales last into the late evening, but with
frontal passage show a quick drop off and shift to the SW. Seas
remain elevated due to continued SW swell after the combined
winds waves and swell that bring levels up to 15-20ft Tuesday
evening. Inner channel winds increase to small craft with the
front then drop off through the morning. Lynn Canal winds remain
elevated as N-S pressure gradient tightens.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind from 6 PM AKST this evening through late tonight for
AKZ317.
Strong Wind from 9 PM AKST this evening through late tonight for
AKZ323.
MARINE...Gale Warning for PKZ641-642-644-651-652-661>664-671-672.
Small Craft Advisory for PKZ012-013-021-022-031>036-053-643.
&&
$$
SHORT TERM...PRB
LONG TERM....NC
AVIATION...GJS
MARINE...PRB
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