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FXAK68 PAFC 190034

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
434 PM AKDT Thu Apr 18 2024

afternoon through Sunday afternoon)...

Wet and windy weather persists into the weekend as an atmospheric
river lingers near southern Kenai Peninsula and Kodiak Island. A
Flood Watch is in effect for Kodiak Island, while a Flood Advisory
is in effect for the Kodiak City area. We continue to monitor rain
amounts and intensity associated with the atmospheric river. Aside
from an increase in precipitation amounts for Kodiak Island, few
major changes were made with this most recent forecast package.

Diving into the details... an Omega block is in place over Alaska
and Canada, with a high amplitude ridge centered over NW Canada,
a deep trough and closed low nearly stationary to the south of the
Alaska Peninsula and Kodiak Island, and a deep trough and low
east of the ridge over the heart of Canada. An atmospheric river
extends from the East Tropical Pacific north and west to Kodiak
Island and the western Gulf of Alaska. A series of upper level
waves rounding the upper low are tracking westward across the Gulf
to Kodiak Island, bringing a resurgence of stronger winds and
precipitation from this afternoon through late tonight.

The upper level ridge strengthens over Southcentral through
tomorrow, keeping rain limited to areas south of Seward.
Meanwhile, steady rain will continue for Kodiak Island, with
periods of moderate to heavy rain as upper level short-waves
continue to pass overhead. There has been some uncertainty with
rain amounts as the atmospheric river oscillates north and south
under the influence of these shortwaves. With models keeping the
front more consistently over Kodiak Island, have increased rain
amounts and durations. The heaviest periods of rainfall will
likely occur this afternoon/evening, and from early Friday morning
through the afternoon. Expect lighter but steady rainfall
throughout for Kodiak Island, bringing an additional 2-3 inches of
rain from what has already been observed yesterday and today.
Rain lingers for Kodiak Island through Saturday, though
precipitation should be much lighter as the surface low occludes
and the tropical moisture tap is lost.



ALEUTIANS (Days 1 through 3)...

A vertically stacked low remains roughly 300 miles to the south
of Sand Point and the Alaska Peninsula this evening. An axis of
cooler temperatures aloft (-10 degrees Celsius at 850 mb)
stretches from the north central Bering down through the Eastern
Aleutians as flow wraps cyclonically into the southern side of the
low. Wind remains elevated within this thermal gradient with a
swath of northerly gales extending from east of the Pribilof
Islands down into the Dutch Harbor and Akutan. Ongoing snow
showers across Unalaska have kept visibility between one half mile
and one mile, as winds gusting over 30 knots are resulting in
poor visibility within the falling snow. Temperatures are likely
too warm at the surface for snow on the ground to blow around, but
reduced visibility and deteriorated conditions are forecast to
persist through Friday morning. A winter weather advisory remains
in effect for the Eastern Aleutians through 8am AKDT Friday.
Likewise, a blizzard warning for Toksook Bay has been extended
through 6am AKDT Friday morning as snow and blowing snow with
visibility down to one quarter mile are expected to linger through
tonight. Of note, rain has been observed in Bethel with surface
temperatures below freezing. Thus, a mix of freezing rain and snow
is possible into tonight with light icing on surfaces.

East of the stacked low, strong southeasterly flow is spilling
into the Kamishak Gap. Easterly winds have gusted to around 35 mph
through much of the day for Iliamna, Koliganek, and New Stuyahok.
Winds across all of Southwest Alaska look to remain elevated
through late Saturday. Above normal temperatures are forecast for
the region with mostly dry conditions forecast for Friday and
Saturday. The pattern finally begins to change over the weekend as
the vertically stacked low south of the AKPEN falls apart and a
new developing low moves into the western Bering by Sunday.



.LONG TERM FORECAST (Days 4 through 7: Monday through Thursday)...

Changes are expected as the weather pattern is becoming more
stable conditions through the forecast period. An upper level
ridge is slowly losing its hold across Mainland Alaska. A Western
Gulf of Alaska low weakens and slips across the Gulf to Haida
Gwaii by Wednesday before dissipating. A well developed Aleutian
low maintains some additional upper level support from both
Siberia and and the Northern Pacific through midweek. A number of
moderate shortwaves rotate through the pattern across the
Aleutians and along the Western Coasts.

Periods of rain spread across Southcentral Alaska through
Wednesday from the Kenai Peninsula to the Canadian Border. The
most active weather will be associated with the Aleutian/Bering
low and its front on Monday. Heavy rains spread across the Central
and Eastern Aleutians, with mixed rain and snow over the Bering
with the low center. Gusty Southerly winds move with the front
from the North Pacific, across the Pribilofs and St Matthew
Island. Rain continues to spread into the Alaska Peninsula with
the front through Tuesday, and into Southwest Alaska late Tuesday
and Wednesday. Another round of locally heavy rains moves into
Kodiak Island late Tuesday through Thursday. Gusty Southeasterly
winds moves through the Barren Island into Kamishak Bay Wednesday
and Thursday.




PANC...VFR conditions will persist. The Turnagain Arm wind is
expected to continue bending southward down Cook Inlet while
generally northerly winds persist over the airport. Southeasterly
winds are flowing across the mountains and generating mountain
waves. Low level wind shear concerns are borderline for the
forecast period with a majority of the shear to remain near or
above the 2000 foot level. At the surface, winds are coming from
the northwest over the terminal and although there is a small
chance for winds to mix and become gusty this afternoon, winds are
expected to remain lighter.




FXAK69 PAFG 191242

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
442 AM AKDT Fri Apr 19 2024

Snow and blowing snow winding down over the Yukon Delta
coast today. Dry and warm conditions will persist
into the weekend for Interior Alaska. Winds have diminished
across the Alaska Range. Strong northerly winds will
develop over the Bering Strait over the weekend with
25 to 40 mph possible.


Models are in decent agreement in the short term with ridging
building in over the west coast and remaining over the Interior
through the weekend. An upper level low over Eastern Russia
will lift northward through Friday, while high pressure builds
over Interior Alaska. Still some uncertainty in the extended
with a front impacting the west coast around mid week next week.

West coast...A weak front near the coast is producing snow
and blowing snow and reduced visibility along the Yukon Delta
Coast this morning. A Winter Weather Advisory is in effect through
Noon. Precip will taper off in the afternoon then pick back up Saturday
morning as another low moves into Bristol Bay. Upper
ridging will build across most of the West Coast over the weekend,
with temperatures warming into the mid 30s to lower 40s. Strong
northerly winds will develop over the Bering Strait over the weekend
with 25 to 40 mph possible.

Interior...Melting continues over the Interior as high pressure
dominates the area. Highs will reach into the upper 50s to low
60s through Sunday. Winds are on the downtrend over the Alaska
Range this morning. Cancelled the wind advisories. A chance
of showers around the Interior on Monday then high pressure
builds back over the area on Tuesday.

North slope...Areas of fog and stratus over the north slope this
morning. Flow looks to shift northwesterly on Saturday as the
current upper system off the West Coast shifts north of the area.
Temperatures will range from the 20s to 30s through the weekend,
falling into the teens and single digits Sunday and Monday. A
chance of snow over the western Brooks Range on Sunday.

Extended Forecast Days 4-7...High pressure will remain over much
of the state early next week. Still some uncertainity but a low
will enter the western Bering and bring a front across the Bering
Strait .

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


AK...Winter Weather Advisory for AKZ825.
PK...Brisk Wind Advisory for PKZ801-802-850.
Brisk Wind Advisory for PKZ807.
Brisk Wind Advisory for PKZ811-815.
Brisk Wind Advisory for PKZ814.
Brisk Wind Advisory for PKZ857-858.
Brisk Wind Advisory for PKZ859.
Brisk Wind Advisory for PKZ860.
Brisk Wind Advisory for PKZ861.


FXAK67 PAJK 182301

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
301 PM AKDT Thu Apr 18 2024


The nice spring weather continues for SE AK today as
clear skies and warm temperatures continue. Little changes were
made to the short term forecast today. Biggest changes that were
made was to reduce the winds in the latter half of the short term
period as well as raise high temperatures for Friday with the
persistent weather continuing for the end of the week.

.LONG TERM.../Saturday through Thursday/...Dry weather for
SE AK lasts a bit longer into Saturday as the approaching front has
slowed down. As high pressure ridge shifts east a trough from a 500
mb low over the Western AK Gulf extends over the SE Gulf then
rotates over the Panhandle from S to N Saturday night into Sunday.
Cloud cover increases and temps return to seasonable normals with a
narrower diurnal range. The front will shear apart as it loses upper
level support so not expecting much in the way of rainfall amounts.
Operational models still have some spread on if this front will
produce widespread precip but ensembles have been consistent keeping
in some light precip over entire area. GFS/NAM/Canadian show good
agreement so leaned towards those. As the front rides over the ridge
another short break in precip looks to occur Monday as another low
moves in from the west. "Active" weather continues into next week
but again ensembles show higher probability of precip than the
operational models, mainly due to uncertainty from blocking ridge
break down, large model spread, and likely leaning on climatology.
Northerly winds diminish as pressure gradient weakens with a
directional shift occurring through Saturday into Sunday. Marine
winds generally less than 20 kts. So overall lower confidence in
forecast details for the mid range.


VFR conditions will persist across the panhandle with clear skies
and localized afternoon sea breezes through the TAF period. Winds
go near calm and variable overnight. Winds increase during the
afternoon, but should remain less than 15 kt with an isolated
gusts up to 20 kt possible.


High pressure over the region keeps a stalled front over the
gulf through Saturday. Strong to near gale southeasterly winds
will persist over the central gulf through Saturday night before
high pressure moves E of the region. Over the inner channels,
generally light to gentle winds prevail with moderate to fresh NE
to E outflow winds out of Taku Inlet, back side of Douglas Island
and S Lynn through Cross Sound.


MARINE...Small Craft Advisory for PKZ022-053-641>644-651-652-661>664-671-




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