853
FXZS60 NSTU 210053
AFDPPG

Area Forecast Discussion
National Weather Service Pago Pago  AS
153 PM SST Thu Jun 20 2024

.DISCUSSION...
Satellite imageries show a cluster of thunderstorms over Swains
Island and west of Savai`i Island. This is an indication of
instability still lingering within the area of responsibility
(AOR). Also shown on the satellite imageries is a line of clouds
to the south-southwest associated with a cold front. A boundary
layer where the light and gentle easterlies merge with the gentle
south and southeast winds will remain over the area through
Friday. Model data shows a high pressure system to the southwest
migrating east and pushing the aforementioned cold front over the
islands by Friday and Friday night. By Saturday, models are
suggesting that the cold front will move further north as the
moderate to fresh trades move into the area.

Although cold fronts are usually dense, bringing severe weather
conditions, this one will likely increase the potential for
showers, but not flash flooding. These conditions are further
supported by the increased values in the upper air (RAOB) data
from this afternoon (21/00Z) compared to the last 12 hours.
However, a mid-level high pressure system will remaining
stationary over the area helping to draw in dry air, and
suppressing any major cloud growth.

Long term model solutions show the aforementioned high pressure
system maintaining the moderate to fresh trades for the rest of
the forecast period. Showers embedded within the trade wind flow
will pass over the islands from time to time. Overall conditions
for the new week will be breezy, cool and dry.

&&

.Marine...
Observations reported from the PacIOOS buoy near Aunu`u show wave
heights within the 5 to 7 feet range with peak periods around 12
to 14 seconds long. This translates to surfs nearing 9 feet, which
is below advisory thresholds. A light and gentle breeze has
remained over the islands throughout the day and will continue
through at least Friday. However, the aforementioned high
pressure system to the southwest moving south of the islands will
produce moderate to fresh southerlies on Friday night turning
southeast on Saturday night. Also generated by this high pressure
is a large south swell moving into the American Samoa waters by
this time frame into the new week.

&&

.PPG WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

JTAllen