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FXAK67 PAJK 202256
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
256 PM AKDT Thu Jun 20 2024

.SHORT TERM.../Through Friday night/...Passing trough tonight
will increase clouds and give isolated rain showers to areas along
the far northeastern gulf coast. As the trough moves north, wind
speeds in the gulf will increase to around 15 to 20 knots. Inner
channel speeds will increase to near 10 to 15 knots as the trough
axis moves north, then decrease back to 5 to 10 knots.

Friday into Friday night is when the next front will come near.
The parent low will track west to east, way out in the gulf,
towards Haida Gwaii. As this low marches east, it will swing a
front north into the panhandle. This front will have minor impacts
to the panhandle.

The impact with the biggest concern is the marine winds along the
front, where speeds could get up to 25 knots, with some evidence
of near 30 knot wind speeds. As the front moves north, inner
channel winds speeds will respond by increasing to near 15 to to
20 knots. Greater details for the marine forecast can be found
in the Marine section.

This front will also give the area passing light rain. Rain
amounts aren`t anything too impressive with 24 hours amounts
mainly less than 0.50 inches.

Normally with increased cloud cover and rain in the forecast,
temperatures would be expected to cool a bit. But with energy
coming up from the south, overnight lows are still expected to
bottom out near 50 and afternoon highs ranging from the low to mid
60s in the southern half to the upper 60s to low 70s in the north.
Temperatures like this are a few degrees above normal.

.LONG TERM.../Saturday through Tuesday/ A stacked low pressure
center will slowly track eastward across the southern Gulf through
Saturday then across Haida Gwaii and Hecate Strait Sunday. The
low will be weakening some as it moves through, however bands of
vorticity wrapped around the low will result in convective bands
of showers, which tend to have some gusty winds. Those bands of
showers will namely be over the southern panhandle closer to the
low center. The lower latitude of the track will cause offshore
flow across the northern half of the panhandle, which should
reduce rainfall potential and amounts there.

Models are indicating potential for an easterly wave on Sunday.
There is disagreement on where said wave would cross from B.C. and
extends over the panhandle. However, then central panhandle is
looking most likely at this time.

Through the first half on next week, another upper level low will
track eastward across the southern gulf and give a repeat of
offshore flow across the north and shower potential across the
south. Additionally, there will be potential for convective
development in Canada most days which could spill over the Coast
Mountains.

From mid-week onward, upper level flow will shift out of the NW as a
ridge of high pressure pushes into the western gulf. This will push
most lingering showers back out of the area...but bring back
potential for marine layer clouds over the gulf coast.

&&

.AVIATION...Marine layer has primarily moved offshore through the
afternoon hours, with the lone holdout being Sitka which may break
out briefly but then see a higher cloud deck move in later tonight.
The rest of the panhandle will see continued relatively clear
conditions with light winds aside from some local sea breezes
through the evening hours, such as Skagway. A weak front will push
into the panhandle tonight bringing lower ceilings and some light
rain potential. By Friday morning a stronger low will move into the
eastern gulf with higher shower potential spreading into the
northern panhandle. Overall not expecting significant LLWS for the
TAF period, though can expect ridge top winds to pick up out of the
east heading into tomorrow afternoon for the southern and central
panhandle with the approaching system.

&&

.MARINE...For the Friday into Friday night time frame, marine
wind speeds will be greatest along the front. In the gulf, speeds
are expected to reach 20 to 25 knots with some evidence of up to
30 knots. These winds will first be seen in the far southern gulf
and will track northward, reaching Cross Sound area late Friday
morning. Speeds will decrease Friday night as the front more-or-
less shears apart.

For the inner channels, the winds will respond as the front moves
north. But as the front gets farther away from the parent low, the
forcing will be limited, so the speeds won`t respond quite as much
the farther north it goes. Current timing has the front increasing
wind speeds in the southern inner channels to around 20 to 25
knots Friday afternoon with those speeds lasting into Friday
night. Farther north, mainly areas north of Frederick Sound, wind
speeds will increase to around 10 to 15 knots beginning late
Friday afternoon into Friday night.

For the far northern inner channels, winds looks to stay out of
the north at around 10 knots or less.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ036-641-642-661>664-671-672.

&&

$$

SHORT TERM...GJS
LONG TERM...FERRIN
AVIATION...STJ

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