589
FXZS60 NSTU 130126 CCA
AFDPPG

Area Forecast Discussion...CORRECTED
National Weather Service Pago Pago AS
226 PM SST Fri Jun 12 2026

.Short term [tonight through Sunday night]...
Latest satellite imagery shows a line of showers and embedded
thunderstorms (trough) to the north of American Samoa. Along the
western fringes of this trough is a developing area of low
pressure to the east of Vanuatu. The pressure gradient between
equatorial low pressure associated with the trough and a very
strong high pressure system near New Zealand will hold and
further intensify the strong gusty southeasterly trade winds over
American Samoa this weekend. Southeasterly trade winds up to 30
mph with higher gusts can be expected throughout the short term
forecast period.

This afternoon`s 00Z RAOB upper-air observation revealed a very
dry and stable mid-level atmospheric profile, unfavorable for any
widespread or deep convection. The high pressure near New Zealand
will hold these stable weather conditions for American Samoa
through the weekend as it keeps the trough to the north. A
shallow moist layer in the low-levels may still allow for
isolated to scattered passing trade wind showers, but overall
rainfall should be limited and below average through the short
term forecast period.

.Long term [Monday through Friday]...
The high pressure system near New Zealand will begin to gradually
weaken and move to the east to start the new week. This will
allow the developing low pressure near Vanuatu to drift
southeast, moving near Fiji and continuing to the south of
American Samoa by early through midweek. As this area of low
pressure moves south of the territory, it will pull the trough to
the north closer to the islands. This is forecast to bring
increased rain chances by as early as Monday night continuing
through midweek. However, there is still signficant model
disagreement regarding the exact progression of this trough, so
potential for flooding is uncertain at this time.

With the pressure gradient weakening over the early to mid-week
time frame, trade winds should weaken below advisory levels
Monday into Tuesday as they begin to turn out of the north to
northeast, becoming a light flow by Wednesday. Light winds and
passing showers are forecast for late week as the trough moves
away to the southeast.

&&

.Marine...
Today`s data from Aunu`u buoy show that combined seas with a
large south swell and southeasterly wind waves are continuing to
bring very large and hazardous seas and surf to American Samoa`s
coastal waters and south facing shorelines. The swell component
is gradually weakening with time. The swell is expected to weaken
enough by tomorrow to make the short period southeasterly wind
driven waves the dominant wave component.

As the swell weakens, wave heights may briefly subside 9 to 12
feet tomorrow. However, strong to near gale force winds over the
weekend should build seas back to 10 to 14 feet by Sunday. With
lower period times, surf heights will decrease slightly, but will
remain at high-end advisory to borderline warning levels, capable
of sweeping away people near vulnerable shorelines and generating
powerful rip currents. These large and choppy wind driven waves
will make navigation extremely difficult to impossible for small
vessels and inexperienced mariners. Seas are expected to begin
gradually subsiding Tuesday as wind speeds decrease, but will
still remain rough until midweek.

&&

.PPG WATCHES/WARNINGS/ADVISORIES...
High Surf Warning remains in effect.
Wind Advisory remains in effect.
Small Craft Advisory remains in effect.

&&

$$

Barton