139 
FXZS60 NSTU 230112
AFDPPG

Area Forecast Discussion
National Weather Service Pago Pago  AS
212 PM SST Thu Oct 22 2020

.DISCUSSION...
A moist and disorganized area of shallow convections, associated 
with a trough axis just north of the islands, is seen on latest 
satellite IR and VIS imageries lingering in the AOR through the
weekend. A very broad area of high pressure near New Zealand has 
held this trough in the area since the beginning of the week. GFS
and ECMWF 18Z model runs have been keeping the trough close to 
the AOR through the new week. Models are showing a train of low 
pressures stringing along the trough axis, likely producing flash
flooding conditions across the territory over the weekend. Even 
though cloudy to overcast conditions were observed for the 
majority of the day, minimal weather activity has not been evident
around the islands. Still, the increased chance of numerous to 
frequent showers is expected for the short term forecast. Upper 
air observations from this afternoon (23/00Z) also supports the 
latest model solutions. A dry patch in the 850 to 750 mb levels 
then wet conditions thereafter gives more confidence in increase 
flash flooding conditions. Therefore, expect gentle to moderate 
breeze and a wet short term forecast.

With the high pressure to the south and a ridge building to the 
north, these two features will likely compress the trough over 
the area in the beginning of the long term forecast. This is 
clearly seen on the latest model data, TPW moisture and theta-e 
projections. This scenario is prolonged through midweek before 
trending downward. Expect moisture to persist in the region before
drier conditions move into the AOR. Minimal showers with light and
variable winds is expected for the majority of the long term
forecast. 

&&

.Marine...
Current Wave Watch III model runs show seas remaining at 5 to 7
feet for the rest of the forecast period. PacIOOs Aunu'u buoy
continue to show seas around 6 feet with short periods between 8
to 11 seconds. This southeasterly swell will linger in the area 
as winds will remain at gentle to moderate breeze (10 to 15 knots)
for the majority of the short term forecast. Although winds will 
briefly reach fresh trades (20 knots) on Friday overnight into 
early Saturday morning, embedded thunderstorms in the trough will 
likely increase the chances of building seas and surfs in the 
area. This may prompt the issuance of advisories for small crafts 
and high surfs over the weekend. In the meantime, no advisories 
are in effect for all coastal waters of American Samoa.

&&

.PPG WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

JTAllen