543
FXZS60 NSTU 260121
AFDPPG

Area Forecast Discussion
National Weather Service Pago Pago AS
220 PM SST Wed Jun 25 2025

.Discussion...
The latest satellite imageries continue to show a trough just east of
the Manu`a Islands and another trough just south and west of the Samoa
Islands lingering in close proximity of our area of responsiblity (AOR).
Thunderstorm activity and heavy showers embedded within the troughs will
likely impact the area for the next 12 to 36 hours. Upper air observations
(RAOB) from this afternoon (26/00Z) shows a moist atmospheric profile,
with thunderstorm possibility, and flash flooding potential remaining in
the area. Gentle to fresh northeast winds at the surface to around 800 mb
together with ASCAT satellite swaths suggests the motion of the trough to
the east will be south, southwestward while the trough to the south and
west will move east as it creates a convergence zone over the islands.
Model data show the latter trough connected to a low pressure system to
the south of the Samoa Islands, pulling the trough as it migrates east.
With this convergence in place, the potential for thunderstorms and flash
flooding will likely remain for tonight through at least Thursday night
as model data projects. Therefore, the flood watch will continue through
at least Thursday night.

Long term model projections show the aforementioned troughs moving away
from the area by the end of the week into the new week. Also shown in model
data is a high pressure system building from the west-southwest, keeping
a gentle to moderate easterly breeze for the remainder of the forecast
period. Embedded scattered to numerous showers within the easterly flow
will remain for this time frame as well.

&&

.Marine...
Manual observations of ocean conditions on the southern shores
show surfs increasing, likely reaching high surf advisory
thresholds. These observations have been confirmed by the data
from the PacIOOS buoy near Aunu`u. Significant wave heights of
8 to 10 feet with periods less than 10 seconds continues to
impact south and east facing shores for the rest of the day.
Model data also show consistent seas building for the rest of the
forecast period peaking tonight through at least the weekend.
Combined seas of 9 to 12 feet is expected for tonight through
Wednesday, subsiding to 8 to 10 feet for the rest of the forecast
period. Gentle to moderate easterlies will prevail for tonight
through the rest of the period. Thus, the advisories for small
crafts and high surfs will remain in effect for this time frame.

&&

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

&&

$$

JTAllen