661
FXZS60 NSTU 060045
AFDPPG

Area Forecast Discussion
National Weather Service Pago Pago AS
145 PM SST Sat Sep 5 2026

.Short term [tonight through Monday night]...
This afternoon`s 00Z RAOB upper-air observation revealed a stable
layer of dry air based at around 850 mb, above a shallow moist
layer. Latest satellite imagery is also reflective of this stable
weather pattern with limited convective growth in the area. Any
rainfall would be limited at isolated to scattered (20-30%
chance) light and brief passing showers in this environment. A
ridge of high pressure to the south of the islands will hold this
stable weather pattern and increase southeasterly trade winds up
to 20 mph at times through the remainder of the weekend.

A weak surface trough is observed on satellite around 350 miles
E-NE of the Manu`a Islands. As the high pressure shifts eastward,
this trough will slowly shift westward and closer to American
Samoa. This surface trough is expected to move near the islands by
late Monday. Only subtle low-level convergence for ascent is
anticipated due to southeasterly winds shifting to easterly.
Additionally, GFS model proximity soundings indicate moisture
associated with this trough remaining confined to the lower
levels of the atmosphere. Given only subtle convergence and a
shallow layer of instability, the trough is anticipated to only
bring a slight increase in rainfall, with flooding being
unlikely.

.Long term [Tuesday through Saturday]...
Slightly increased rainfall chances may persist through Tuesday
as the trough lingers in the area. The initial high pressure
system will move out of the area to the east while another area of
high pressure develops off the east coast of Australia by midweek.
This second high pressure system will continue to maintain east-
southeast trade winds of through the long term forecast period.
While these trade winds may be breezy at times (up to 20 mph),
GFS and ECMWF model data also project periods of weaker wind
speeds (as low as 10 mph).

&&

.Marine...
Wave heights have been in a subsiding trend with a weakening of
the trade winds. However, a long period south swell maintains
seas and surf at borderline Small Craft Advisory (wave heights
peaking near 8 feet) and High Surf Advisory (surf heights near 10
feet) levels. Therefore, High Surf and Small Craft Advisories
remain in effect. The influence of the south swell will weaken
going into early portions of the new week, but a slight increase
in wind speeds should maintain wave heights at a similar level.
By midweek, wave heights are projected to drop below Small Craft
Advisory criteria due to the aforementioned periods of weaker
wind speeds (as low as 10 knots at times).

&&

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

&&

$$

Barton