889
FXZS60 NSTU 070050
AFDPPG

Area Forecast Discussion
National Weather Service Pago Pago  AS
150 PM SST Sun Sep 6 2026

.Short term [tonight through Tuesday night]...
Surface observations throughout the day and latest ASCAT
satellite wind estimates indicate that east-southeasterly trade
winds have slightly increased over the past 24 hours, now with
speeds of 15 to 20 mph driven by a ridge of high pressure south
of the islands. Mostly clear skies are observed in the area in
latest satellite imagery and surface observations with only few
to scattered passing cumuli clouds of limited vertical depth.
This afternoon`s 00Z RAOB upper-air sounding shows a stable trade
wind inversion based around 850 mb, indicative of the reason for
limited cloud growth in the area. This stable pattern will keep
rain chances low tonight, but a brief isolated shower is possible
(~20%).

Despite the stable weather that is currently observed over
American Samoa, just 200 miles northeast of the Manu`a Islands, a
surface trough is seen on satellite imagery along the northern
edge of the stronger trade winds, slowly moving westward. While
the core of this trough is projected to remain north of the
territory, subtle convergence in the trade wind flow along its
southern fringes should still be enough to increase rain chances
late Monday into early Tuesday. Only weak surface convergence and
ascent is not likely to be strong enough to fully erode the trade
wind inversion and moisten the profile. Therefore, moisture from
the trough should remain confined to the lower levels of the
atmosphere and only a slight increase in rainfall is expected,
with little to no threat for flooding.

.Long term.[Wednesday through Sunday]..
As the trough leaves the area, the surface high pressure center
driving the trade winds should move eastward and out of the area
by midweek. Another high will develop off the east coast of
Australia, but American Samoa is projected to be in between
weather patterns for at least a few days over the latter half of
the week. This should slightly weaken trade winds to around 10 to
15 mph with only weak ridging to the south. The next high
pressure system will begin increasing southeasterly trade winds
as it moves off the east coast of Australia and into the
Southwest Pacific. There is some model uncertainty regarding the
exact timing that trade winds will increase again, but it could
occur as early as Saturday.

&&

.Marine...
A decrease in peak and average wave period times is indicative of
the south swell weakening across the area. This has decreased surf
heights below advisory levels, and as a result the High Surf
Advisory was cancelled yesterday evening. However, the increase in
wind speeds has maintained wave heights in the 6 to 8 foot range.
Wave heights should remain in this range through early portions of
the new week, maintaining choppy conditions that are difficult for
small craft to navigate. By midweek, wave heights are projected
to subside below Small Craft Advisory levels due to the
aforementioned weakening of the trade winds.

&&

.PPG WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory

&&

$$

Barton