FXZS60 NSTU 160051
AFDPPG

Area Forecast Discussion
National Weather Service Pago Pago  AS
151 PM SST Wed Apr 15 2026

.Short term [tonight through Friday night]...
This afternoon's RAOB upper-air sounding shows that the low and
mid-levels of the atmosphere have become significantly more moist
and unstable compared to the overnight hours due to a nearby
trough to the north and east of the territory. A weak surface
convergence in the light easterly flow is indicated by satellite
wind estimates (ASCAT) over the islands. This weak convergence
helped to develop a line of showers that has overspread from
Manu'a early this morning to Tutuila by late morning to early
afternoon. Showers have tended to be light as the convergence is
very weak and the trough remains displaced to the north and east,
keeping the flooding threat very low despite coverage briefly
increasing to numerous showers. As the surface wind flow becomes
variable tonight, rain chances should decrease back to scattered
without the influence of the convergence.

The trough will remain north and east of the islands throughout
the duration of the short term forecast period. Light surface
winds (under 10 mph) are expected to hold for this time frame.
Showers are expected to return to scattered Thursday into Flag
Day, with near to slightly below average rainfall for this time
of year.

.Long term [Saturday through Wednesday]...
During the weekend into the new week, a weak surface ridge of
high pressure will develop to the south of the territory. This
should bring an easterly trade wind flow regime by late weekend
through the new week. Since the ridge is forecast to be weak,
trade winds are not expected to be overly strong, likely
remaining in the 5 to 15 mph range. Isolated to scattered passing
showers are possible embedded in the tradewind flow.

&&

.Marine...
Following the rough ocean conditions over the weekend, seas have
gradually subsided throughout the week, down to around 5 feet at
Aunu'u buoy which is favorable for small craft. The favorable
seas and light winds will continue through the remainder of Flag
Day week, bringing ideal conditions for mariners. South swells
are expected to increase period times Thursday into Friday.
However, these swells are expected to be small with seas
remaining in the 4 to 6 foot range. Still the long period times
may lead to some stronger currents along vulnerable shorelines,
conditions for mariners on the other hand may become even more
favorable as long period swell is less choppy that short period
wind waves. For the extended period, wave models do not indicate
any signifcant change in ocean conditions.

&&

.PPG WATCHES/WARNINGS/ADVISORIES...
None

&&

$$

Barton