Graphical Hydro Meteorological Discussion

788
FXAK68 PAFC 030127
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
527 PM AKDT Wed Apr 2 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Tonight
through Saturday)...

A digging trough over the Bering Sea and Aleutians is leading to
amplification of the downstream ridge over southern AK and the
Gulf. While some high cirrus clouds have formed over Southcentral
today, dry conditions and warm temperatures continue across the
region. The amplification of the upper flow will ultimately lead
to a pattern change, with the ridge progressing eastward to Canada
on Thursday, opening the way for a deep trough and Pacific surface
low to impact Kodiak Island, the Gulf waters, and Southcentral AK
Thursday night through Saturday. The forecast for this storm
system is on track, with few changes made to the going forecast.
A strong leading frontal system will track well out ahead of the
parent low, lifting northward across the Gulf Thursday night and
then stalling over the northern Gulf Friday afternoon through
Saturday afternoon as a vertically stacked low sets up shop south
of the Alaska Peninsula and Kodiak Island. The vast majority of
impacts from this storm will be along the coastal zone, with
strong easterly winds and rain. Snow levels will remain fairly
high, starting out at around 1000 to 1500 feet early Friday
morning, then rising 1800 to 2500 feet by late Friday. Thus, snow
should not be a big issue along the road system. Inland areas will
remain mostly dry with strong downsloping flow, though there
could be an occasional brief period of light precipitation as weak
upper short-waves track inland. Temperatures will remain above
normal, with a trend toward above freezing night-time temperatures
due to extensive cloud cover.

-SEB

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days
1 through 3: Tonight through Saturday)...

Key points...

* Winter Storm Watch upgraded to Warning for Unalaska
-Heavy wet snow, blowing snow and reduced visibilities
-Onset early Thursday morning

* Blizzard Watch for the Kuskokwim Delta Coast continues
-Strong winds with blowing snow
-Onset Thursday morning

Very little to the weather picture has changed over the last 12
hours, other than fine tuning of warning products. A deepening
north Pacific low continues to lift towards the Aleutian Chain
this afternoon. A warm front lifting ahead of this low will slam
into a cold front that lay draped from Norton Sound, southwest
through Adak. The low is expected to slow down and stall through
Friday, southwest of Kodiak Island. Where the interaction of warm
moist air from the south and cold arctic air from north collide,
heavy snow will occur. Current guidance is putting the island of
Unalaska right in the cross-hairs. Unlike the early winter storm
that brought similar snow amounts to the island, the bulk of the
dynamics will remain south of the chain. That said, conditions are
still going to be favorable to produce a lot of heavy and wet
snow over a prolonged time period. Snow totals for the city may be
lower side of expectations, but the influence of terrain will
allow those totals to swell rapidly with minimal elevation gains.
Unalaska and the harbor are should see 10 inches to more than a
foot, while amounts over a foot and a half cannot be ruled out.
The other aspect of this event will be the winds. Winds and cold
air will be driving across the Bering and will easily be
sustained above 25 mph, starting around dawn on Thursday with
gusts at or above 40 mph. Winds will steadily increase and peak in
the overnight hours on Thursday, lasting into Friday, potentially
surpassing 60 mph gusts. The combination of the driving winds and
periods of heavy snow will lead to whiteout conditions. Snow will
taper off Friday into Saturday with winds abating later into
Saturday and Sunday.

North along the Kusko coast the blizzard watch continues. Trends
are starting to focus more on the bulk of the snow pushing later
into the day and along the far western coast (Kipnuk to Toksook
Bay and across to the Nunivak Island). Blizzard conditions are
looking a little less likely, but blowing snow will still be a
hazard.

&&


.LONG TERM FORECAST (Days 4 through 7: Sunday to Wednesday)...

The most significant feature on the Alaska Weather map is an
elongated trough stretching from the Arctic through Interior
Alaska to the Gulf of Alaska through the forecast period. Closed
lows over Northern Alaska and the Gulf weaken through midweek.
Although there is some oscillation within the elongated trough,
there is little movement. Ridges over the Western Canadian
Provinces and the Bering also weaken through the period. Forecast
continuity remains good with a GFS / ECMWF / Canadian blend, but
minor differences with shortwaves gliding through the pattern
represent the variations and short term changes in forecast.

A moderately strong surface low over the Southern Gulf of Alaska
spreads locally heavy rainfall from the Eastern Aleutians over the
Alaska Peninsula through Monday. Gusty winds over the AKPEN
linger through midweek. Locally heavy rains marches across Kodiak
Island and the rest of Southcentral Coastal zones through
Wednesday. Areas of locally moderate snow spread over Southwest
Alaska into the Interior, and diminish through midweek. A well
developed low and front approaches the Western Aleutians for
Sunday, but dissipates to the South of the chain by Tuesday.

- Kutz

&&

.AVIATION...

PANC...VFR conditions are expected to continue through the TAF
period. A ridge of high pressure is developing along the coast,
which will induce winds through Turnagain Arm this
afternoon/evening. Given the warm temperatures and heating in the
Valley, there`s a chance the wind moves over the terminal this
afternoon/evening. We`re not anticipating a strong wind at this
time but gusts up to 20 kt are possible. Calm conditions are then
expected overnight, with a return of the Turnagain wind possible
Thursday afternoon and evening.

&&


$$

089
FXAK69 PAFG 022205
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
205 PM AKDT Wed Apr 2 2025


.SYNOPSIS...
Snow showers across the Interior taper off this evening.
Temperatures increase this weekend as southerly flow over the
Alaska Range brings increased winds and warmer, drier, conditions
to areas north of it including Fairbanks. A front brings
additional snow to the West Coast from the YK Delta Thursday
afternoon and into the Southern Brooks Range by noon Friday.

&&

.KEY WEATHER MESSAGES...
Central and Eastern Interior...
-Light snow tapers off this afternoon. Snow changes over the light
rain or rain/snow mix as temperatures increase later this
afternoon.
-Gusty southwest winds this afternoon and evening may produce
areas of blowing snow where snow showers remain. This is most
likely in the hills north and east of Fairbanks.
-Temperatures increase through the weekend with highs reaching
near 50 from the Alaska Range through the Middle Tanana Valley
and the upper 30s to mid 40s elsewhere.
-Temperatures decrease at night to below freezing almost
everywhere creating a freeze-thaw cycle through the weekend.

West Coast and Western Interior...
-Southwest gusts to through the Norton Sound through this
afternoon allowing scattered showers and patchy fog along the
Northern and Eastern coast of the Norton Sound.
-A front approaching the YK Delta Thursday afternoon will bring
another round of snow to the West Coast through Saturday. The
heaviest snow will fall in the Yukon Delta and lower Yukon with
amounts of 4 to 6 inches.
-Winds shift northerly Thursday with the strongest winds along the
Yukon Delta coast with gusts 30 to 35 mph. With falling snow
there will be areas of blowing snow along the coast with
visibility falling to half a mile or less at times.

North Slope and Brooks Range...
-Light snow moves over the North Slope tonight with amounts
generally less than an inch falling east and south of Utqiagvik.
-Easterly winds increase Friday along the Arctic Coast with the
strongest winds being from Point Thompson east with gusts up to
35mph possible. Brief periods of low visibility due to blowing
snow is possible with conditions improving Friday evening.

&&

.FORECAST ANALYSIS AND DISCUSSION...
A 1006mb low over the Kotzebue Sound is bringing a front across
the Interior and into the North Slope through tonight. This
feature was responsible for today`s snowfall across much of the
Alaskan Interior and is bringing gusty southwest winds behind the
main body of precipitation creating blowing snow potential where
snow showers remain. Daytime heating will allow for possible light
rain showers in the south central Interior including Fairbanks
this afternoon. This low moves north and east across the North
Slope as it fills in this afternoon bringing light snow to the
North Slope south and east of Utqiagvik with totals generally less
than an inch.

Aloft, a 491 dam low sits in the high Arctic with a 560 ridge in
the Gulf of Alaska supports southwest flow through Thursday. This
low fills in and moves further north becoming a less dominant
feature Thursday with the Gulf ridge moving east into Canada and
increasing heights across the Interior. A shortwave low in the
Bering Sea rotating around the Arctic low strengthens as it
merges with a Pacific Low that moves north from 40N latitude into
the Gulf of Alaska on Friday creating broad southerly flow across
the Alaska range as it pushes against the ridge to its east. This
flow will create a downsloping effect north of the Alaska Range
warming temperatures well above normal in the southern Interior
this weekend. This low moving into the Gulf merging with the
Bering short wave will help fuel a front of precipitation
stretching from the YK Delta to the Central Brooks Range Friday
into Saturday. The front will bring the heaviest snow to the
YK Delta and lesser amounts further north until it reaches the
southern slopes of the Brooks Range which will see similar amounts
to the YK Delta.

EXTENDED FORECAST DAYS 4-7...
Monday sees a shortwave low move east from Siberia across Northern
Alaska. Models disagree on the strength and southern extent of
these features, but agree on it moving into the Chukchi sea Sunday
night into Monday. This will weaken the ridge, push it east, and
lead to ridge breakdown across the Alaskan Interior. This will
bring snow to the North Slope and might, depending on how far
south the low moves across the state, bring another round of
light snow to the Interior Monday and Tuesday.

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


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Winter Weather Advisory for AKZ825.
Winter Weather Advisory for AKZ834-838-842.
PK...Brisk Wind Advisory for PKZ803>805-852-853.
Brisk Wind Advisory for PKZ809.
&&

$$

Stokes

356
FXAK67 PAJK 022252
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
252 PM AKDT Wed Apr 2 2025

.SHORT TERM...Dry weather and clear skies remain the big story
through Thursday, though a change in the pattern is in store
beginning Friday.

Aloft, a strong upper level ridge continues to remain over the
Gulf of AK, bringing strong mid and upper level northwest flow
across the panhandle. Closer to the surface, this has resulted in
widespread dry weather, with only some occasional mid or upper
level clouds rotating around the ridge and into the panhandle. A
weak marine layer formed off the coast Tuesday night, but largely
remained offshore.

Wednesday night will remain largely similar, with clear skies,
barring a few locations with mid to upper level cloud cover. While
a marine layer may form once again, anticipate that it will stay
offshore. Thursday will likewise remain similar to Wednesday,
with high temperatures in the 50s for many locations near sea
level. Thursday night will see some upper level cloud cover begin
to spread across the panhandle, but expect dry weather to prevail
across the area until Friday.

Winds will remain on the lighter side, with sustained winds
occasionally reaching gentle to moderate breeze over land-based
areas. The pattern will begin to change on Friday as the ridge
begins moving off to the E, opening up a path for storm systems
rotating around the flank of an advancing trough to race up from
the SE into the area. For more information, see the long term
forecast discussion.

.LONG TERM...The deep low forming in the gulf is currently moving
northeast with models dropping as low as 970mb as the front
reaches the outer coast. A weak atmospheric river will provide
plenty of moisture to help fuel this system and bring an end to
the nice weather we`ve been experiencing. This front will be
accompanied by strong gales and sea heights possibly exceeding 18
ft off the coast in the eastern gulf. This system is expected to
bring elevated winds to the inner channels, with the potential for
gales near channel entrances. Temperatures will continue to rise
through this system before slowly falling through the next week.
Precipitation associated with this system will impact the
panhandle through Saturday peaking overnight into Sunday and
lingering through the beginning of the week. The northern and
central coastal regions will experience the onset first, as well
as the highest accumulated amounts as the front moves eastward.
Yakutat is expected to receive the most precipitation with 1-3
inches through the weekend. The majority of impacts will occur
Saturday afternoon, and the active pattern is expected to continue
through the rest of the week.

&&

.AVIATION.../Until 00Z Friday/...CIG & VIS conditions will remain
within the VFR flight category, & generally benign SFC winds are
in store for Southeast Alaska through the TAF period. The only
appreciable variation will be between sea and land breezes. LLWS
values will remain benign through the period.

&&

.MARINE...With the weak pressure gradient, Inner Channel winds
should remain largely around light breeze, perhaps occasionally
reaching moderate breeze through Thursday night. Marine winds and
waves are expected to remain on the quiet side until the end of
the week when a gale force front is expected to move into the Gulf
by Friday. Seas are expected to increase along the outer coast
with this front with peaks near 20ft along the outer coast Friday
night before winds decrease again.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ652.

&&

$$

SHORT TERM...GFS
LONG TERM....ZTK
AVIATION...JLC
MARINE...GFS

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