Graphical Hydro Meteorological Discussion

845
FXAK68 PAFC 020111
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
511 PM AKDT Tue Apr 1 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Tonight through Friday)...

It`s become a remarkably warm spring day for a number of spots
across Southcentral thanks to a combination of strong upper level
ridging moving overhead and mostly clear skies (aside from the
Copper Valley) and gusty offshore winds out of favored gaps along
the Kenai Peninsula and Kodiak Island. Both Seward and Kodiak
have managed to soar above 60F as gusty north to northwest winds
cause downslope warming off of terrain and increase mixing of warm
air aloft under the ridge in place. Even much of Anchorage is
seeing the first day of the season reaching into the 50s with
ample sunshine this afternoon.

The pattern will shift slowly as the longwave ridge gradually
shifts more into the Gulf Wednesday, then towards the Alaska
Panhandle and Northwest Canada on Thursday. As the high shifts
eastwards, flow will become more southwesterly on Wednesday,
putting an end to the gusty offshore gap winds along parts of the
Gulf coast. The pressure gradient driving these winds will
essentially reverse by Wednesday night as a coastal ridge builds
along the north Gulf Coast and over Prince William Sound. This
could help a weak Turnagain Arm wind develop that could bend into
west Anchorage late Wednesday night into Thursday morning before a
down-inlet gradient pulls the Turnagain Arm jet back away from
town later on Thursday morning.

From Thursday night into Friday, an expansive North Pacific low
drifting slowly north will push a gale force front across the
Gulf, with the boundary then stalling close to the Gulf coast by
Friday afternoon. Southeast winds across the Kenai Peninsula and
along the Turnagain Arm will strengthen significantly along the
Turnagain Arm as the front approaches, with gusts as strong as 35
to 50 mph possible from Thursday evening through at least Friday
evening. Stronger winds will likely mostly stay out of the
Anchorage Bowl, except possibly for a short window during peak
daytime heating on both Thursday afternoon and Friday afternoon,
where boundary layer instability could be enough to mix easterly
winds aloft down off of the Hillside.

The other side of this frontal system of course will be light to
moderate rainfall and mountain snowfall quickly filling in across
the Prince William Sound region and eastern Kenai Peninsula
Thursday night into Friday. Snow levels initially could be low
enough for wet, slushy snow through Turnagain Pass, but warming
temperatures should transition snow over to rain even at pass
level by Friday afternoon. Thompson Pass will have the best chance
for seeing several inches of accumulating snow through the end of
the week where snow levels could stay low enough for all snow for
much of this event.

-AS

&&


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

An elongated front, stretched from Nunivak Island to Amchitka, is
steadily advancing eastward across the Bering and Aleutian Chain.
Meanwhile, a weakening ridge over portions of Southwest Alaska
continues to shift southeastward, out of the area. Widespread
areas of fog across the Eastern Aleutians, Alaska Peninsula and
coastal Southwest Alaska are breaking down this evening, however
there is the potential for areas of fog to return in similar areas
Wednesday morning. A trough driving the front over the Bering
will push into the Kuskokwim Coast later this evening and will
likely contribute to additional periods of reduced visibility from
light precipitation. Areas further south across the Greater
Bristol Bay region have remained largely dry and are forecast to
stay dry into Wednesday.

Through Wednesday, the front is expected to slow, somewhat
anchoring over the Central/Eastern Aleutians to the Pribilofs,
promoting a light rain/snow mix and steady northerly winds.
Influence from the front`s northeastern extent over the Kuskokwim
Delta will weaken through Wednesday, providing a reprieve from the
precipitation in the area for the time being. Along with the
return of fog to areas of Southwest and the Aleutians, Wednesday
will be largely benign, leading to a stark pattern shift beginning
early Thursday morning.

Late Wednesday night, a robust North Pacific Low will advance into
our area, merging with the remnants of the front across the Bering
and amplifying the pattern. As the low continues to push northward
toward the Alaska Peninsula, northerly winds will increase
significantly across the Eastern Bering and across the Eastern
Aleutians including Unimak Island/Pass. Winds through gaps will be
strong by Thursday afternoon, reaching Storm-force along the
southern side of the eastern Aleutians. Given the strong northerly
flow, temperatures are expected to settle near freezing at sea-
level in places such as Dutch Harbor and Akutan. This system will
also be bringing with it a significant shot of moisture allowing
for the potential of heavy snow. Unalaska, Akutan, and Nikolski
are currently expected to see the worst conditions from this
system. As such, a Winter Storm Watch has been issued for the
Eastern Aleutians beginning Thursday morning and lasting through
Saturday morning.

Similarly to the northeast over the Coastal Kuskokwim Delta
including Kipnuk and Nunivak Island, the resurgence of winds and
snow along the frontal boundary show potential to drive blizzard
conditions. A Winter Storm Watch has also been issued for this
area from Thursday morning through Saturday afternoon. The
heaviest snowfall rates and strongest winds are expected Thursday
evening through Friday. Snow and gusty winds will taper off
beginning late Friday from south to north along the coast as the
front moves into the eastern Bering. Snow and blowing snow is also
possible for communities south and east of Kipnuk. However,
blizzard conditions are not expected for these locations.

Please reference these Watches and stay tuned to the forecast as
we hone in on the potential impacts of this strong late Winter
system.


&&

.LONG TERM FORECAST (Days 4 through 7: Saturday to Tuesday)...

Some increasing amplitude comes with the changes on the Alaska
Weather map through the forecast period. The upper level Eastern
Bering trough slips into the Central Alaska Mainland for Tuesday.
An upper level closed low South of Alaska Peninsula moves into the
Southern Gulf of Alaska and consolidates its link with the
Mainland trough by Tuesday. An upper ridge over the Western
Canadian Provinces adjusts to the movement and shortwaves rotating
through the pattern, while a second upper ridge builds over most
of the Bering through the period. A forecast blend of the GFS and
ECMWF maintains good continuity over the features` strength and
movement through the weekend, but the GFS slides to the South with
the Gulf of Alaska low by Tuesday.

A moderately strong surface low South of the AKPEN pushes across
the Southern Gulf of Alaska through Tuesday. Locally heavy rains
and gale force winds span from the AKPEN across Kodiak Island
through Sunday. High end gales are expected through bays and
passes. The rain and gusty winds spread over the Southcentral
Alaska coasts to the Canadian Border through Tuesday. Locally
heavy snow is expected over higher terrain inland Monday and
Tuesday. Rain and snow extends from this low into Southwest
Alaska, with gusty winds from Nunivak Island into the Eastern
Aleutians. Out west, a well developed low and front approaches
the Western and Central Aleutians, bringing rain and gusty winds
through Monday, with most of more significant weather remaining
offshore through Tuesday.

- Kutz

&&

.AVIATION...

PANC...VFR conditions and light winds will persist until late Wednesday
night when the Turnagain Arm jet develops and could bend gusty
southeasterly winds towards the terminal.

&&


$$

167
FXAK69 PAFG 012316
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
316 PM AKDT Tue Apr 1 2025

.SYNOPSIS... Snow continues along the West Coast and through the
Interior through Wednesday afternoon. Strong southwesterly wind
gusts possible through Wednesday morning across the West Coast and
through the Interior. Temperatures increase across the Interior
later this week with highs reaching the mid 40s on Friday.

&&

.KEY WEATHER MESSAGES...
Central and Eastern Interior...
-Snow continues through Wednesday night with an additional 1 to 4
inches expected across the Central and Southern Interior with up to
7 inches expected in the hills of the Fairbanks North Star Borough.
-Strong southwesterly winds continue through this evening and pick
up again early Wednesday morning. Gusts up to 30mph possible in the
valleys with up to 40mph possible along highway summits through this
evening with blowing snow potential.
-Temperatures warm through the end of the week with highs reaching
near 40 Wednesday and into the mid and upper 40s this weekend.
-Wednesday afternoon will see increased chances of rain snow mix and
some areas of just rain are possible. The majority of the
precipitation will have already fallen by Wednesday afternoon
limiting rain accumulations.

West Coast and Western Interior...
-Southwesterly winds will continue through Wednesday morning
bringing light wintry mix, snow, mist, and fog across the YK Delta,
Norton Sound Coast, and Southern Seward Peninsula.
-Additional snowfall will mainly be in the 1 to 3 inch range for the
West Coast and Western Interior, but locally higher amounts up to 5
inches are possible at higher elevations of the Nulato Hills before
snow tapers off Wednesday.
-Southwesterly gale force winds are possible tonight and Wednesday
morning that could push water over ice, but blowing snow potential
is limited by warm temperatures.
-Northerly winds and snow chances increase across the Yukon Delta
Thursday night which may bring reduced visibility due to blowing
snow through Saturday.

North Slope and Brooks Range..
-West winds increase this afternoon before diminishing overnight
with a passing front. There may be brief periods of blowing snow
from Point Thompson east as wind gusts as high as 45 mph are
possible this evening, but lack of falling snow will limit
visibility restrictions.


&&

.FORECAST ANALYSIS AND DISCUSSION...
A 984mb low in the high Arctic, a 1030mb ridge over the central
Aleutians, and a 1040mb high building south west of the Aleutians is
creating a large area of southwest flow across the West Coast and
into the Interior. This is bringing a large amount of moisture
across the state as a shortwave rotating around the Arctic low moves
east into Canada today. There will be a brief lull in snowfall this
afternoon before a weak low in the Northern Bering strengthens and
moves east into the Seward Peninsula overnight providing yet another
round of snow to the West Coast and much of the Interior. This will
bring cooler temperatures to the West Coast and North Slope, but the
Interior will stay warm through the rest of the week.

A 965 to 976mb low moves into the Gulf of Alaska with models
disagreeing on its strength. The GFS and NAM are showing this low as
976 with the ECMWF and Canadian models resolving the feature as
stronger at 965mb. Models are in good agreement about this feature`s
location and a front bringing additional snowfall to the West Coast
and snowfall with chances of rain to the Interior with the greatest
accumulations along Yukon Delta and the southern Brooks Range.


&&

.EXTENDED FORECAST DAYS 4-7...
A low in the Gulf of Alaska drapes a front across the state from the
YK Delta through Ambler and to the central North Slope. This front
will move east through the weekend bringing additional snow to the
Western Interior and the southern Brooks Range. A weak low moves
east from Siberia across the North Slope Sunday and Monday bringing
additional snow to the Arctic Coast. Some additional snowfall is
possible Sunday and Monday in the southeastern Interior and the
Yukon Uplands, but models differ on timing, area, and quantity of
snowfall. Midweek next week may see a low move into the western
Bering Sea, but confidence is low as models all have different
strengths and timings for this low.


Coastal Hazard Potential Days 3 and 4... Near gale-force west-
southwesterly winds across the Norton Sound may push water through
cracks in ice. Flooded shorefast ice is therefore possible across
the eastern Norton Sound Tuesday night into Wednesday. Winds
diminish quickly Wednesday afternoon limiting impacts.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Winter Weather Advisory for AKZ834-838-842.
Winter Weather Advisory for AKZ839>841-843>845.
Winter Weather Advisory for AKZ847.
PK...Brisk Wind Advisory for PKZ801-808-809-855.
Brisk Wind Advisory for PKZ802-807-853.
Brisk Wind Advisory for PKZ803>805-852.
Brisk Wind Advisory for PKZ806.
Brisk Wind Advisory for PKZ812-858.
Brisk Wind Advisory for PKZ813-814.
Brisk Wind Advisory for PKZ815-859>861.
Brisk Wind Advisory for PKZ816-850.
Brisk Wind Advisory for PKZ817-854.
Gale Warning for PKZ851.
Brisk Wind Advisory for PKZ856.
&&

$$

Stokes

335
FXAK67 PAJK 012150
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
150 PM AKDT Tue Apr 1 2025

.SHORT TERM...The blocking pattern continues for SE AK through the
short term period. With that in mind, made very minimal changes to
the forecast and left most of the going forecast the same as is.
The northerly gradient that has been in place is expected to
weaken and winds will continue to weaken. Otherwise, mostly clear
skies and warm daytime temperatures will continue.

.LONG TERM...Dry conditions remain until Friday. Winds have decreased to
southerly light breezes for the majority of the panhandle preceding
the gale force front expected to reach us Friday night. Temperatures
continue to rise slowly through the week, with the majority of the
panhandle expected to see highs near or above 50 degrees going into
the weekend.

The deep low forming in the gulf is currently moving northeast with
models dropping as low as 975mb as the front reaches the outer
coast. 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.
Precipitation associated with this system will impact the panhandle
through Saturday peaking overnight into Sunday. 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 2-3 inches
through the weekend. The majority of impacts will occur Saturday
afternoon, and the active pattern is expected to continue through
the weekend.

&&

.AVIATION.../Until 00Z Thursday/..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
exception will be PAGY, which will see some relatively gusty
southerly winds up to between 15 & 20 kts into this evening before
becoming light & the gusts picking-up, once again, tomorrow
afternoon. LLWS values will remain benign through the period.

&&

.MARINE...With the weakening pressure gradient, Inner Channel
winds should decrease in speed this evening and into the overnight
hours. 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...None.

&&

$$

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

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