618
FXAK67 PAJK 211218
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
418 AM AKDT Fri Jun 21 2024

.SHORT TERM...Our pattern change continues this morning as clouds
are racing ahead of the low and associated front in the gulf.
This low is expected to bring rain and slightly cooler
temperatures to the area for the weekend. Current radar and
satellite rain rate products show pockets of rain already starting
to approach the outer coast area including Sitka. Winds are
expected to come up as this system moves closer. Along the outer
coast, winds are expected to get up to 25 knots as well as along
Clarence Strait. Across other parts of the panhandle, winds are
expected to come up with the approaching low but should remain
lower than the expected winds for the Outer coast. The brunt of
the rain is expected to move in this afternoon and evening as the
system moves closer to the panhandle. Right now, the heaviest rain
amounts look to be along the mountains of southern Baranof island
and then south. Most places though are not expected to get above
an inch of rain with this system moving in. With the cloud cover
already over the panhandle, overnight temperatures have stayed
warm. But the increased cloud cover could also hinder how warm we
get today even with the warm origin of this system. Forecasted
temperatures for today were left unmodified due to the uncertainty
of how warm we could get today.

.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...

Anticipating deteriorating flight conditions from south to north
across the panhandle through the period as a low pressure system
moves into the Eastern Gulf of Alaska, overspreading rain showers
under BKN to OVC skies. For southern TAF sites, Sitka over to
Petersburg and southward, expect low end VFR to MVFR flight
conditions and elevated winds by 18z as front and rain showers
push inland with CIGS AoB 5000ft. Conditions deteriorate further
to MVFR flight conditions after 00z with CIGs AoB 2500ft and VSBYs
near 4 to 5 statue miles. Main LLWS concerns will remain limited
to southern coastal TAF sites between 00-06z. For northern TAF
sites along and north of Icy Strait, including PAJN, expecting VFR
flight conditions through 00z with CIGS dropping to AoB 5000ft
after 00z as rain showers begin to move into the northern
panhandle.

&&

.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/MARINE...SF
LONG TERM....Ferrin
AVIATION...NM

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