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FXAK67 PAJK 192255
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
255 PM AKDT Wed Jun 19 2024

.SHORT TERM.../Through Thursday night/...A weak weather front is
making its way northeast this afternoon and will displace the
surface ridge located just offshore the outer coast. As the ridge
shifts east, cloud cover will increase and a chance of
precipitation re-enters the forecast for Southeast Alaska by
Thursday morning. Have only a slight chance of rain is the
forecast for tomorrow, but PoPs increase to 30-50% by late
Thursday night for locations north and west of Clarence Strait.
The coming cloud cover will not be the marine layer that we have
seen these past few days, so any significant clearing of the skies
tomorrow afternoon in maximum daytime heating is not likely. Not a
very auspicious start to summer with the solstice occurring
Thursday evening at 6:13pm.

Afternoon thunderstorms are once again prevalent over the
interior, The Yukon, and British Columbia but are not threatening
Southeast Alaska as of this afternoon. With a shift in the surface
ridge to the east, more stable air over SEAK tomorrow will aide in
inhibiting thunderstorm activity tomorrow, so the Tongass should
remain safe from any wildfire starts. With that in mind, have been
looking at red flag parameters for Skagway. There, it is windy
enough and dry enough for a red flag warning, but at 68 degrees
not warm enough yet.

With such a weak pressure gradient, forecast winds are once again
quite light. The only meaningful wind action will be northern Lynn
Canal and Skagway, as it was today. Biggest change to winds was to
decrease wind speeds over the canal and Skagway by a full 10 kts
when forecast small craft conditions did not materialize. No
impactful winds or seas on the outside either.


.LONG TERM.../Friday into next week/...The next round of rain and
wind approach the panhandle Friday with the rain chances lasting
into the weekend.

We`ll be watching 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 80% chance) bring
rain to the area, especially in the southern half. Farther north,
confidence is a little lower, so stuck with PoPS around 50 to 70%.
This is due to low confidence in how far north the front, and
organized precip, will go.

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. Increased winds in Clarence
Strait to up to 20 to 25 knots due to EFI tables highlighting the
wind speeds in the southern inner channels.

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...The marine layer and associated cloud deck has
pushed out of the inner channels but it is still along the out coast
and impacting PASI CIGS. The rest of the forecast area is pretty
clear with some cue developing along some of the islands. The marine
layer will move back into the inner channel to be in the Icy Strait
area down Chatham Strait, Fredrick Sound and then into Clarance
Strait. The marine layer may reduce some CIGS and VSBY to be near
IFR conditions, mainly along the coastal locations. Some high
clouds from the approaching front will begin to move other area
from the west and the marine layer will begin to break up/lift
through Thursday.

&&

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

&&

$$

SHORT TERM...Fritsch
LONG TERM....GJS
AVIATION...ABJ

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