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000
FXAK67 PAJK 252313
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
313 PM AKDT Thu Apr 25 2024

.SHORT TERM...Little in way of changes for Southeast Alaska, as
surface ridge continues to keep lighter winds, minimal cloud
cover with exception of lower clouds. Anticipate a marine layer to
reform in the northeast gulf coast tonight that will likely
spread into the coastal area to include: Yakutat, Cross Sound,
Perhaps Peril Strait, Western Chichagof Island and Baranof
Island, and Western Prince of Wales Island. The clouds and patchy
fog under the clouds could start to spreading through Western Icy
Strait towards Gustavus by Friday morning.

Overall short term dry until perhaps late Friday night as a front
starts lifting northwards the southern portion of the panhandle,
when chance PoPs start moving in.

.LONG TERM...The main theme through the weekend is that an open
longwave trough will move into the Gulf, bringing in a 988mb to
998mb surface low, with an escalation in southeasterly winds,
waves, and some light rain. The 988mb low demands attention, but
is a manifest of the uncertainty found within the deterministic
trends. For now, have found a happy medium in the ensembles, with
a hedge in the wind field towards the more serious GFS and NAMNEST
solution. Confidence is very low that we see a 988mb low develop
on the Gulf on Saturday; however, upstream development and model
trends will have to be monitored closely as more high resolution
models start to capture this feature. Main questions to answer in
the coming 24 hours as we watch cyclogenesis is how our waters
will either stabilize, or add to the instability, of the air mass,
which has implications on how much momentum we can mix down to
the surface thus impacting surface wind speeds. If the more robust
solutions featuring instability comes to fruition, there is
potential to see gale force winds near Dixon and along the western
coast of Prince of Wales, along with more elevated and sustained
southwest winds Sunday into Monday which increases and prolongs
the southwest swell a bit.

QPF (quantitative precipitation forecasts) continue to trend
downwards but there is some hope if the more aggressive
deterministic solutions come to fruition, which could steer some
relatively higher IVT into the south. For now, the current
forecast utilizes a modern statistical approach, with 48 hour rain
totals coming in under 1 inch for most of the region over the
weekend into Monday.

Tuesday a secondary low forms aloft near Queen Charlotte sound,
with northerly flow developing across the Gulf as high pressure
builds from the west, likely leading to warming temperatures and
clearing skies into Wednesday. With that said, will need to watch
the potential for a shallow marine layer keeping some areas a
little cooler. Diurnal wind regimes also come to mind.

Attention turns to end of next week as another system lifts into
the Gulf, with the potential to see a bit more moisture moving
into the northern regions.

&&

.AVIATION...Conditions ranging from 3000/5 to CAVU with lower
conditions to the south, if you want to call 3000/5 "low". No
impactful winds, no wind shear, no problems. One exception: low
level marine clouds are expected to move in again tonight and
invade the inner channels possibly as far as Gustavus as well as
the outer coast. Early to mid morning clearing should produce
another day like this afternoon turned out. Go Fly!

&&

.MARINE...
The Gulf continues to be docile, with buoys 82,83, and 84
reporting southwest 3 to 4ft swell at 8 to 10 seconds. Expect
the swell to increase a touch tonight but concerns remain low
through Friday.

Threats escalate Saturday into Monday for our mariners operating
smaller vessels across southeast Alaskan waters as a band of 25-30
knot southeasterly winds and 7 to 12ft south southwest fresh seas
develop, south of Cape Fairweather along our coast. Expect the
highest significant wave heights west of Prince of Wales near
Dixon Entrance, with southerly 5 to 9ft fresh seas in far southern
Clarence Strait exposed to the open waters of Dixon. Mariners
operating in Icy Strait will also feel an increase of 15 to 20
knot easterly winds Saturday, with the most concern around Pt.
Couverden and Skull Island.

Some wording of caution around Saturday for the south. There is
potential to see a brief period of gale force winds which would
lead to an increase in significant wave heights; however,
confidence remains too low to put this threat into the forecast.
Will need to continue to monitor the system as it moves off the
Aleutian Islands into the Gulf.

Tidal variations are relaxing compared to the large swings we saw
with the full moon on April 23rd, with Third Quarter on May 1st.

Many thanks to the operators in our waters who reported their
conditions to WFO Juneau throughout the week.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...None.

&&

$$

SHORT TERM...Bezenek
LONG TERM....AP
AVIATION...Fritsch
MARINE...AP

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