603
FXAK67 PAJK 152221
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
221 PM AKDT Sat Jun 15 2024

.SHORT TERM...Ridging due to a high pressure out in the central
gulf continues through the short term and into the long term,
meaning reduced clouds, warming temperatures, and, in this case, a
marine layer over the gulf. Currently on satellite, the marine
layer has retreated nice to the outer coastal waters; however, the
layer will move in later tonight into Icy Strait and Sumner
Strait. Current thinking is that the layer will remain intact up
until the western portion of Icy Strait. There are smaller
probabilities (lower than 25%) that the marine layer will reach
Gustavus with visibilities lower than 1 SM. On the southern end,
there is good confidence (greater than 80%) that the marine layer
will inundate the Western portion of PoW Island and Sumner Strait
up until Port Protection. Expect this marine layer to return
Sunday night as well, reaching further into the inner channels.

Looking towards the mountains bordering Canada, there is
increasing confidence that isolated thunderstorm activity will
move into the area both later this afternoon and tomorrow. A few
convective cells near Whitehorse are showing rapid development in
Canada, moving NE. Looking at NUCAPS soundings, areas directly NE
of White Pass look to have CAPE values 500 J/kg or more. White
Pass and Haines Customs are the most likely area where
thunderstorms could pass tonight and tomorrow, but conditions look
favorable (by SE AK standards) for at least one or two cells to
develop as far as Glacier Bay.

.LONG TERM...Summer is here in the long term. Get out and enjoy
it while you can.

Monday a ridge will continue to dominate the region, with the
axis retrograding under the influence of a closed low moving along
the northern coast of mainland Alaska. Dry, with afternoon sea
breezes in the inner channels is the main theme over the next few
days. By the end of the week, an extension of a closed low over
the Aleutians attempts to form into a longwave trough and move
into the Gulf, bringing some onshore flow, cooler temperatures,
and increasing PoPs through the weekend. However, models are being
a bit too optimistic on ridge breakdown, so have pushed back the
timing on this feature.

Threats to coastal and gulf waters remain low, with our swells
significant deep ocean wave heights remaining under 8ft. With that
said, stout 15 to 20 knot northwest winds along the coast will
bring short period wind driven waves to the west coast of Prince
of Wales and into Dixon Entrance.


&&

.AVIATION.../Through Sunday afternoon/...Not a total bluebird day
across Southeast Alaska this afternoon or tomorrow, but there are
very few places with CIGs below 5000 ft. Light winds from the
surface to ridge tops...except of course for Lynn Canal.
Yesterday it was also spicy in Skagway. Today the challenging
winds on final are in Haines. And for tomorrow...either or both.
No impactful PIREPS today and I suspect there will be few if any
tomorrow. One thing to watch out for is thunderstorm activity
approaching from British Columbia and The Yukon. More often than
not, these CBs will weaken as they cross the ice field & Coast
Mountains, but keep an eye out for them, as they are currently in
the forecasts issued by Juneau and the AAWU for our side of the
border. As always, PIREPS to the FSS even during good flying
weather are appreciated. Good SEAK pictures from aloft and fan
mail can be sent directly to WFO Juneau (juneau.weather@noaa.gov).

&&

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

&&

$$

SHORT TERM...NC
LONG TERM....AP
AVIATION...Fritsch

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