787
FXAK67 PAJK 032337
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
337 PM AKDT Thu Apr 3 2025

.SHORT TERM...Near 47N 158W a storm force surface low is
maturing, being reinforced by a parent trough at 500mb with
positive vorticity advection (PVA) upstream of the main trough
axis. Satellite derived winds and model guidance show strong
agreement with the current the situation; 25 to 33 knot winds
associated with the triple point on the eastern flank and a broad
fetch of gale force SW winds behind that feature. This low will
continue to lift north and east into the Gulf of Alaska over the
next 24 hours as PVA crosses downstream of the trough axis,
indicating full maturity, with the low aloft closing. Expect the
coast to begin to feel E-SE winds freshen up overnight Thursday,
reaching gale force by Friday morning. Of particular concern is
Cape Suckling, where 45 knots sustained winds gusting to storm
force later Friday is becoming more likely; certainly, a bit of an
Alaskan rodeo for this time of year. For further details on
winds, see Marine Section.

Regarding precipitation, for sea-level locations light to moderate
rain arrives Friday along the northern coast and pushes east
across the Panhandle overnight into Saturday morning. Heaviest
rainfall expected Saturday morning into Sunday. For much greater
detail see Hydrology section.

.LONG TERM...The deep low currently situated south of the Aleutian Islands is
continuing to move northeast. A front extending from this low
pressure center will move into the eastern Gulf along the outer
coastline by Friday night, with gale force winds being expected just
along the outer coast and lasting into Saturday morning. A weak to
moderate atmospheric river is expected to bring up plenty of
moisture into this system, however the majority of the moisture is
expected to stay just off the outer coast of the panhandle. The
highest precipitation rates will be just west of Yakutat, with
Yakutat itself being expected to see around 2 inches of total liquid
precipitation throughout the weekend. The rest of the outer coastal
areas as well as POW, Ketchikan, and Annette Island will see some
decent amounts of precipitation during this weekend, between 0.5 to
1 inch of liquid precipitation in 24 hours on Saturday, before
dissipating into Sunday. The front will push through the panhandle
Sunday into Monday morning, bringing some lighter rates of rainfall
as it pushes northeast. This will also bring some precipitation to
the border of the Klondike Highway, which along with lower snow
levels of less than 3,000 feet and wet bulb temperatures of less
than 32, will likely fall as a rain snow mix with very little of it
actually accumulating by Monday morning.

An active weather pattern is expected to continue after this first
system with another front being expected to move into the northeast
and hit the panhandle Monday night into Tuesday. The majority of the
panhandle is expected to remain wet for most of this week as the
deep low in the Gulf is expected to stay stagnant off the west
coast, while smaller lows are expected to track up into the eastern
Gulf coast and bring even more precipitation by the end of the week.
This is largely due to the deep trough sitting over the Gulf and
bringing more of these lows up along the east Gulf coast from the
south.


&&

.AVIATION...End to the days of minimal hazards to aviation as gale
force front moves in Friday evening into Saturday from the west.
Rain hits NW coast first with a drop in CIG and VIS along with
increase in LLWS. As the front moves in widespread precip drops
conditions to MVFR/IFR. LLWS and increased turbulence mainly along
coastal areas. Rising freezing levels as warm mid level airmass
tracks in.


&&

.MARINE...Gulf: Our benign sea state will begin to change
overnight Thursday as our low lifts into the gulf, driving E-SE
gale force, to strong gale force, winds. Of most concern is Cape
Fairweather west towards Kayak Island, where persistent strong
gales Friday evening into Saturday are becoming more likely. The
biggest concern is the fresh seas stacking up on Kayak Island and
running west towards the Kenai Peninsula, higher than previously
anticipated. We have coordinated with WFO Anchorage to show 22 to
25 ft seas near Cape Suckling, a 3 to 5 ft increase from previous
forecasts. For the remainder of the coast, expecting fresh seas
building to 18 to 20ft Friday. Behind this system expect S-SW
swell of 15 to 18ft.

Inner Channels: Southerly onshore winds escalate Friday across
the inner channels, driving E-SE fresh to strong breezes across
most channels south of Icy Strait. Peril Strait will likely see
near-gales at times coming out into Salisbury Sound. As the front
moves over the region Saturday morning we will see gusty
southerly winds of strong breezes impact most areas.

&&

.HYDROLOGY...
1) Flooding is not anticipated.
2) Snow levels above 3000 ft for the majority of the panhandle,
reaching 8000ft for the central and southern coast.
3) 1 to 3 inches of 24 hr QPF at sea level, with the heaviest
amounts along the coast. Less moving into the interior panhandle.

After the onset of precipitation west of Yakutat on Friday, we will
begin to see a shift to a much higher availability of moisture
Friday night as an atmospheric river moves up into the eastern Gulf.
This will bring more moderate to even heavy precipitation Saturday,
with the majority of the heaviest rates being just west of Yakutat
and around Cape Suckling. The CW3E guidance shows both the EC and
GFS in agreement of it being a weak (AR-1) to potentially moderate
(AR-2) atmospheric river event for the northeast and southern
coasts, though with most of the moisture not making it into the
panhandle but rather staying further off the coast. This will still
bring 1 to 3 inches of rainfall to Yakutat and the northeast Gulf
coast during the weekend, and up to 1 inch of rainfall for the rest
of the region. Rivers may rise following this system, but flooding
is not anticipated at this time due to the dry soils at sea level
and mature snowpack at elevation that is likely to withstand the
rain.

As expected with most atmospheric rivers, we will see warmer air
moving into the region alongside higher snow levels as the system
comes in Friday. The snow levels Friday will be around 2000 ft,
before rapidly increasing to around 7000 ft along the coast into
Saturday morning. The northern panhandle will see snow levels get to
above 3000 ft before settling around 1500 to 2000 ft as we move into
next week. The snow level around the Klondike Highway will dip below
3000 ft on Friday, before increasing to 3500 ft on Saturday, before
dropping again to below 2000 ft Monday. This will give us some light
snow overnight on Friday along the higher elevations of the highway
near the border, before transitioning into rain into Saturday
afternoon. This will return to a mix by the start of the week, but
with little snowfall accumulating this event due to the lighter
precipitation rates, more hours of sunlight, and warmer road
surfaces moving into the daylight hours. For anyone at higher
elevations, above 4000 ft in the northern panhandle such as those
in the Chugach or St. Elias Mountains, expect feet of heavy and
wet snow.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale Warning for PKZ641-642-644-651-652-661>664-671-672.
     Small Craft Advisory for PKZ022-035-036-053-643.

&&

$$

SHORT TERM...AP
LONG TERM....Contino
AVIATION...PRB
MARINE...AP
HYDROLOGY...AP/Contino

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