656
FXAK67 PAJK 182248
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
248 PM AKDT Tue Jun 18 2024

.SHORT TERM.../Through Wednesday night/...Situation today was very
similar to yesterday and will be similar to tomorrow. Repeating
themes include a marine layer advancing inland from the outer
coast and afternoon Canadian thunderstorms approaching from the
north/northeast with few if any making it over the Coast
mountains. The low clouds associated with the marine layer over
the inner channels will slowly dissipate through the day leaving
much of Southeast Alaska under partly cloudy skies. Strongest
winds will once again be over the far northern inner channels with
southerly winds 10 kts increasing to 20 kt in the afternoon in
Skagway. Also am expecting low end small craft winds in Lynn Canal
by tomorrow afternoon.

A pattern change will begin wednesday night with the approach of a
surface trough from the west. This will displace the surface high
pressure ridge situated over the eastern Gulf which has been
responsible for the marine layer these past few days. The trough
will also re-introduce the possibility of precipitation along the
northern half of the outer coast by late Wednesday night and
heading into the long range forecast period.

.LONG TERM.../Thursday into the weekend/...A weather pattern
change will bring rain and brief elevated winds back to the
panhandle.

High pressure ridging will slide east into Canada as a trough of
low pressure approaches. This trough could bring some showers or
light rain to the area on Thursday. Low confidence on where the
greatest chances will be, so for now, stuck with 20 to 40% PoPS.

Friday into the weekend is when the greater chance for precip
will move in. This is due to a low tracking east through the gulf
towards Haida Gwaii. The associated front will swing north into
the panhandle. This front will likely (greater than 70% chance)
bring rain to the area, especially in the southern half. Farther
north, confidence is a little lower, so stuck with PoPS around 40
to 60%. This is due to questioning just how far north will the
front track.

In addition to the incoming rain, wind speeds will be elevated
along the front as well. For now, went with marine wind speeds up
to 25 knots along the front in the gulf. Euro ENS and GFS ENS give
greater than 60% chance for wind speeds greater than 20 knots
along the front during this time.

As the front tracks through the inner channels, went with wind
speeds around 15 to 20 knots. This was supported by the latest
NBM, EURO ENS, GFS ENS, and EURO AIFS.

After the frontal passage, 500mb ridge looks to build back up but
surface features generally keep light, leftover rain in the area so
for now, low PoPS and light winds linger.

&&

.AVIATION...Generally expecting MVFR with CIGS AOA 025 AGL through
tonight most locations, but with marine layer working its way back
near shore and over some of the inside channels tonight we expect
sites like Klawock, Sitka, Gustavus, and Yakutat to go IFR with
CIGS AOB 010 AGL late tonight into Wednesday morning. Winds will
be generally light for the next 48 hrs, but as we get some breaks
in the stratus late morning into the early afternoon, we expect to
see some seabreeze interactions for Skagway and Juneau tomorrow
with 10-15 kts from the SW. Otherwise no other significant
impacts expected through the forecast period.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012.

&&

$$

SHORT TERM...Fritsch
LONG TERM....GJS
AVIATION...JG

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