000
FXAK68 PAFC 141258
AFDAFC
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
458 AM AKDT Tue May 14 2024
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Today
through Thursday night)...
The cold upper level low responsible for showers (and a few
thunderstorms with hail) over Southcentral yesterday is exiting
south into the Gulf this morning. Vorticity-maxima rotating around
the north side of the low continue to produce isolated showers
early this morning, primarily from the Talkeetna Mountains south
to the Mat Valley and through Tahneta Pass into the western Copper
River Basin. Meanwhile, a surface low over the northeastern Gulf
is being pulled back westward toward the upper low center.
Middleton Island radar imagery shows a North-South oriented band
of rain tracking westward across the northern Gulf and
southeastern Prince William Sound, including Cordova. Further
west, mostly clear skies can be found from Kodiak Island north
to the Kenai Peninsula and much of the Susitna Valley.
Temperatures have once again dropped into the 30s, with isolated
areas down below freezing.
The upper level low will exit eastward across the Gulf today,
though cyclonic flow aloft, with embedded vorticity.maxima will
continue to transit Southcentral. Slightly warmer temperatures
in the upper atmosphere means conditions won`t be quite as
unstable today as they were yesterday. Still expect increasing
showers this afternoon, but fewer showers than Monday and no
thunderstorms. The favored areas for scattered showers will be
the Mat-Su near the Talkeetna Mountains (roughly Willow to
Palmer) along with the Copper River Basin - especially along
the Tok Cutoff and north side of the Wrangell Mountains.
An upstream ridge of high pressure will build eastward tonight,
then move overhead of Southcentral on Wednesday. This will cap
off convection and lead to widespread sunny skies and warm
temperatures. With a surface high building up from the Gulf,
expect stronger sea breezes along the coast. This will lead to
somewhat cooler temperatures for coastal communities compared
to inland areas.
A dissipating front from a deep low in the Bering Sea will
approach Kodiak Island and the western Gulf on Thursday. There
will be very little forcing left, but likely enough to produce
areas of very light rain. This will also lead to increasing clouds
across the western tier of Southcentral Thursday through Thursday
night. Model spread is quiet large with regard to the eastward
progression of the long-wave trough and handling of individual
short-waves. Thus, it is not clear whether any precipitation
will make it up to Southcentral.
-SEB
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA AND THE
ALEUTIANS (Days 1 through 3/ Today through Thursday morning)...
The building ridge over the eastern Bering continues to move into
Southwest Alaska this morning, providing calmer conditions for
much of the area through tonight. This brief period of calmer
weather will be short lived however, as a Kamchatka low in the
western Bering continues to move eastward towards the western
Alaska coastline.
The Kamchatka low`s front extends across the entire western
Bering, producing widespread gale force winds through tomorrow
morning. Warm air behind the front will cause the majority of
precipitation to come in the form of rain as the low progresses
eastward. By Wednesday morning, the range of gale force winds
will be limited mainly to Nunivak Island and the Kuskokwim Delta
before the system weakens further in the afternoon hours.
Widespread precipitation will occur along the western coastline
of Alaska through at least Thursday afternoon. With the ridge
settled over mainland Alaska by this time, there is still some
model disagreement to the eastward shift of the ridge and how
it will effect the placement of the frontal precipitation across
Southwest.
A new shortwave low is also expected to impact the western
Aleutians Wednesday night into Thursday afternoon. While the
exact timing and intensity of the system is uncertain, it does
appear that some precipitation will be likely as it moves
eastward before dissipating Thursday night.
-BS
&&
.LONG TERM FORECAST (Days 4 through 7: Thursday night through
Monday)...
The long term forecast for the Southern Alaska will begin with a
ridge over the Gulf of Alaska sliding east as a shortwave trough
rounds the base of a longwave upper-level trough situated over the
Bering and moves over Southwest Alaska. Models quickly diverge
with regard to the evolution of this system, adding plenty of
uncertainty right at the beginning of the long term forecast. All
guidance has the development of a surface low near the AKPen by
Friday as the shortwave deepens. However, both the GEM and EC try
to hold onto the downstream ridging longer, driving the low and
its moisture into Southcentral. The GFS pushes the ridge south and
provides a more progressive solution with the low tracking east
with only scattered showers along the western slopes of the
interior and coastal mountains. This system then exits to the east
late Saturday.
Sunday may offer a reprieve from any extensive cloud cover and/or
shower activity across the Southern Mainland. But, again, all
models are struggling with the track of various shortwaves
embedded within the longwave trough. While guidance shows a ridge
trying to build north from the North Pacific and western Gulf,
the EC and GEM quickly move the ridge axis east over the eastern
Gulf. This solution would place the entirety of the Southern
Mainland on the back side of the ridge with the resultant
southwesterly flow lending to a more unsettled pattern with
various waves moving along the Aleutian Chain and across the AKPen
and Kodiak Island. The result would be more cloud cover and
chances for rain across the region. The GFS is the more amplified
solution, with a more northerly building ridge remaining in place
longer. This result would slow any upstream storm systems and
likely result in a more northerly storm track, keeping conditions
much more tranquil across the Southern Mainland. Given the
consistency of the GFS and a trend of the EC and GEM ensembles
leaning more toward the GFS, the long term is weighted more toward
the stronger ridge solution.
For the Aleutians and Bering, the longwave trough situated over the
region will likely keep conditions cool and unsettled through the
long term. Any ridging between storm systems would be brief, with
the best chance for high pressure over the Bering late Friday
into Saturday. Any warmer air associated with the ridge, though,
would likely result in widespread stratus and fog due to the
warmer air riding over the cold open waters.
-TM
&&
.AVIATION...
PANC...VFR conditions and light winds will persist.
&&
$$
000
FXAK69 PAFG 141043
AFDAFG
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
243 AM AKDT Tue May 14 2024
.SYNOPSIS...
Numerous showers and isolated storms move to the Eastern Interior
today. Any shower or storm can come with briefly heavy rain and
some pea sized hail. A strong front will impact the west coast on
Tuesday with snow and blowing snow along the Bering Strait. Snow
mixed with rain from Nome east Tuesday night into Wednesday.
Unsettled weather will continue for the west coast Wednesday and
Thursday.
.DISCUSSION...
Upper Level Analysis...
The 00z models initiated well aloft with a shortwave trough
dipping southeast over the Western Interior today. Ridging over
the West Coast today will move east as a strong upper low glides
into the Central Bering this afternoon bringing a strong front to
St. Lawrence Island and the West Coast. Persistent troughing over
the North Slope will be booted out by brief ridging moving in
from the southwest this afternoon. Subtle troughing over the
Interior will traverse east this afternoon with ridging building
in behind it.
West Coast and Western Interior...
A strong front will begin to impact St. Lawrence Island around 8
to 10 AM with strong southerly winds, snow and blowing snow. It
gets into the Bering Strait around 3 to 6 PM and then over to Nome
by 7 PM. The strongest winds will begin to move through during
the afternoon and evening across the entire Bering Strait Region
and continue overnight. Southerly winds could gust up to 45 mph
around Nome with gusts near 60 mph for St. Lawrence Island and
the Bering Strait. Winds will begin to subside Wednesday morning
from West to East and any snow may begin to mix with rain from
Brevig Mission south and east marking an end to any blowing snow
concerns in those areas. From St. Lawrence Island to Wales, it may
remain all snow as cold air wraps in quickly behind the main
front.
North of the Bering Strait, winds will increase this morning with
the strongest winds expected this afternoon and evening around
Kivalina and Red Dog Mine. Gusts up to 55 mph are possible with
snow and blowing snow. The worst conditions in this area may end
up being around Red Dog Mine as strong winds and upslope result in
heavy snow and blowing snow, though Kivalina will also get strong
wind, just not as much snow.
Winter Storm Warnings and Winter Weather Advisory`s have been
issued for all the locations that will see impactful winter
weather conditions.
Central and Eastern Interior...
Numerous showers with isolated storms move over the Eastern
Interior today. The greatest risk for thunderstorms will reside
from Salcha to just south of Circle and Chalkyitsik south to
Northway. Tok and Delta Junction will most likely be spared from
thunderstorms but will still have rain showers and downpours
around. Any shower or storm will likely come with briefly moderate
to heavy rain and erratic wind gusts up to 20-30 mph. Any storm
has the potential to come with pea sized hail. These continue
through about midnight then diminish in coverage. Wednesday looks
to be beautiful with partly to mostly sunny skies and high
temperatures getting into the low to mid 60s. Thursday will come
with plenty of sun as well as highs reaching the mid to upper
60s.
North Slope and Brooks Range...
This evening, a Bering Sea Low will bring a strong front to the
West Coast. Snow is expected to begin in Point Hope around 10 PM
with southerly winds increasing to 30-40 mph with gusts to 55 mph.
The snow may mix with rain at times Wednesday afternoon, but the
winds will remain strong through Thursday morning. A Winter
Weather Advisory is in effect for blowing snow in Point Hope.
Northeast of Point Hope, there won`t be much in the way of snow,
but it will be breezy from Deadhorse west to Barrow with peak
gusts around 30-35 mph Wednesday afternoon into Thursday morning.
Temperatures will be warming up Wednesday and Thursday as well.
Expect high temperatures in the mid 30s along the coast and mid
40s to low 50s in the Brooks Range.
Coastal Hazard Potential Days 3 and 4...
Water levels 2 to 4 feet above normal on Thursday will be
dropping gradually Friday and back to near normal levels on
Saturday.
Extended Forecast for Days 4-7...
Models are in slightly better agreement than yesterday for day 4
and beyond but there is still plenty of uncertainty. We will be
monitoring a chance for another low to move into the West Coast
Friday into Saturday as troughing persists. At this time, this low
looks to be much weaker than what we are currently going through.
Expect a few showers and maybe an isolated storm in the Interior
on Saturday with cooling temps on Sunday.
.FIRE WEATHER...
Numerous showers with isolated thunderstorms move to the Eastern
Interior today. Any shower or storm has the chance to bring
localized wetting rain though most will produce 0.05" or less,
unless it is slow moving. Any storm can be accompanied by small
hail. No precip expected on Wednesday or Thursday. Highs in the
lower 60s on Wednesday with mid to upper 60s on Thursday. Minimum
RH`s around 25-35% today and will decrease to 20-30% on Wednesday
and Thursday. Winds remain relatively light, though any shower or
storm may cause some erratic winds with gusts as high as 20-30
mph possible.
.HYDROLOGY...
A mild breakup on the Yukon River will continue. No impacts have
been reported in Tanana, but there has been ice running for the
last 24 hours and the water has come up. Ice running past Ruby
made its way to Galena today. The water level in Galena rose 2
feet today and has been fluctuating around 114.0 feet since this
afternoon. A heavy run of bank-to-bank ice ran through Galena
during the afternoon. A large channel formed this afternoon around
Bishop Rock and allowed for a heavy run of ice to flow down river.
This run was about 40-45 miles long and extended down river past
Koyukuk near Last Chance. Water levels held steady near Koyukuk.
From Last Chance to Nulato, the river was mostly open with some
chunk ice but there was a series of jams down river of Nulato with
some improvement during the afternoon. Most of the ice has
released at the south bank of the Ninemile Island Jam, and the
jam at river mile 470 appeared weak and degraded. A small jam near
Halfway Island (river mile 460) started to move as well. Water
levels in Nulato were slowly rising but we have not heard of, or
seen any impacts. At Russian Mission, the river is mostly open
upstream but just below, there is a small ice jam. There is some
in place ice in Marshall with chunk ice packed in front of
Marshall. The main break up front is located 7 miles below
Marshall with water levels remaining low. Towards Pilot Station,
the river ice was intact but showed signs of movement and the ice
below Pilot Station appears stronger and more intact. A resident
in Pilot Station reported that the water levels have risen about 5
feet since Sunday.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Winter Weather Advisory for AKZ801.
Winter Weather Advisory for AKZ814.
Winter Storm Warning for AKZ820-821.
Winter Weather Advisory for AKZ822-823.
Winter Storm Warning for AKZ827.
PK...Gale Warning for PKZ801.
Gale Warning for PKZ802-856.
Gale Warning for PKZ803.
Small Craft Advisory for PKZ804.
Gale Warning for PKZ805.
Gale Warning for PKZ806-807-850-853.
Brisk Wind Advisory for PKZ808.
Brisk Wind Advisory for PKZ809.
Gale Warning for PKZ810-811-857.
Brisk Wind Advisory for PKZ812.
Gale Warning for PKZ816-817-854.
Gale Warning for PKZ851.
Gale Warning for PKZ852.
Brisk Wind Advisory for PKZ855-858.
&&
$$
Bianco
000
FXAK67 PAJK 141357
AFDAJK
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
557 AM AKDT Tue May 14 2024
.SHORT TERM...Active weather continues across the panhandle
through Tuesday. The southern half of the panhandle will see more
sustained, stratiform precipitation as an atmospheric river moves
through, albeit with the greatest QPF totals likely to be over
Haida Gwaii. The northern half will continue to feature some
embedded convective elements as onshore flow proves to be the
primary driving force through the day - though this will result in
some relative lulls between heavier bands of precip. The decaying
low over the northern gulf responsible for the current weather
pattern will slowly move E through Tuesday, contributing to the
continued chances of precip even as the system moving through the
S panhandle departs overnight. Much of the panhandle, especially
the northern and central panhandle, could potentially see drier
weather and some clearing skies by the latter half of Wednesday.
The forecast itself remains largely on track, with only minimal
changes made.
.LONG TERM...The primary feature of the mid range forecast is a
weak atmospheric river (AR) Tuesday into Wednesday. Unfortunately
for many in the southern panhandle, the main hose of moisture is
looking increasingly likely to miss our AOR, and instead mainly
impact Haida Gwaii. While there are still indications that places
like the western side of PoW Island and Ketchikan may get
substantial rainfall, the probabilities of this has gone down
based on the run to run ensemble models between yesterday. The
higher weighted models, the GEFS and the GEPS, which previously
were in lock step run to run, appear to have shifted the bulk of
the precipitation southward to match the EPS and ECMWF. In
addition, any additional surface lows being generated off of the
potent jet streak aloft looks to impact Haida Gwaii. While
Ketchikan, Hydaburg, and Craig may see some enhanced northerly
winds as a developing system passes south, the overall threat has
decreased. Again, while it is possible that heavier rains and
winds could impact the southern panhandle, the likelihood is now
lower.
Finally, looking late Thursday into Friday, a ridge begins to
build aloft with a surface ridge in the outer gulf. From this
setup, a short lived drier pattern will extend over the panhandle
with some possible break in clouds, particularly for the northern
half of the panhandle.
&&
.AVIATION.../Until 12 Wednesday/...A post-frontal onshore-flow
showery regime will continue to provide primarily MVFR category
CIG and VIS flight conditions over most of the Panhandle with
periodic rises into low-end VFR category through the TAF period.
The lower flight conditions will be associated with the heavier
showers. SFC winds and LLWS will remain benign through the period.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ661>664.
&&
$$
SHORT TERM...GFS
LONG TERM....NC
AVIATION...JLC
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