Area Forecast Discussion
Issued by NWS Pago Pago

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
FXZS60 NSTU 110145

Area Forecast Discussion
National Weather Service Pago Pago  AS
245 PM SST Mon Aug 10 2020

.Short term...

The latest ASCAT satellite data shows winds strengths are
seasonable to slightly above average for this time of the year.
Satellite data throughout the late morning and early afternoon
shows a decrease in cloud cover throughout American Samoa. This
matches model data as drier mid level air will continue to move
into the region overnight as a high pressure system will slowly
moves away from the territory.

As winds will slowly shift from the southeast to east tomorrow,
this will increase low level moisture in the region. As this
happens, cloud coverage increases with the likelihood of towering
cumulus clouds increasing throughout the day tomorrow. This will
increase the chance of showers to scattered. However, the high
pressure system, that has been responsible for giving breezy
conditions across American Samoa, will retreat further
southeastward to decrease wind speeds across the area.

We are monitoring a tropical wave from the east on Wednesday
through Thursday morning. Models disagree on the timing of the
approaching wave, however agree that severe weather is not likely
during this time. The shift of surface winds, along with incoming
mid level moisture from the northeast will increase the
precipitation forecast to numerous showers during this time frame.

.Long term...

A low pressure system is forecast to form just to the southeast
of Fiji along a tail end of a front on Thursday. As this low moves
south/southeastward, and a high pressure system adjusts while
remaining east of American Samoa, winds will shift from the east
to north/northeast on Thursday night through Saturday night and
wind speeds will be well below average for this time of the year.
Cloud coverage will decrease in the long term forecast and
possibility of showers will decrease to scattered showers during
this time.



The latest information from the PacIOOS buoy shows that seas have
been slowly building throughout the last 24 hours. This is due to
the increase of locally driven trade winds in the region as shown
by period timing data, which is very low at this time. Even
though seas are not expected to reach above the 9 foot mark as it
peaks tomorrow morning, choppy seas are forecast as periods will
be around 6 seconds, which is very low for the region.

By mid to late week, conditions that meet the criteria for a
Small Craft Advisory will decrease as tradewinds decrease and
there is no swell expected to arrive along territorial waters with
no significant weather systems to the south of the region.



A Small Craft Advisory remains in effect.



LaPlante is the U.S. government's official web portal to all federal, state and local government web resources and services.