National Weather Service United States Department of Commerce

Hazardous Heat Across the Western U.S.; Heavy Rain and Flooding in the Southwest and Western Gulf Coast

Dangerous heat will persist over portions of interior California, the Great Basin, and the northern Rockies through Thursday. Heat will gradually spread into the northern Plains today. Across the western Gulf Coast, heavy to excessive rainfall will persist through mid-week. Additionally, the Southwest Monsoon will continue to bring a flash flooding threat to the Four Corners Region this week. Read More >

FXZS60 NSTU 230143

Area Forecast Discussion
National Weather Service Pago Pago AS
243 PM SST Mon Jul 22 2024

.Short term...

The ridge of high pressure remained over the territory today to
give a mix of sun and clouds over the American Samoa islands. The
ridge will remain over the territory through early Wednesday
morning. Therefore, the forecast isn`t changing throughout that
time as easterly trades remain around 20 mph with only a very slight
chance of a passing shower. If a shower moves through, it will be
in the passing form and not heavy.

A trough, currently to the north of American Samoa, is projected
to move over the islands as early as Wednesday afternoon. However,
we are monitoring the possibility of heavy rainfall along the
Wednesday evening and Thursday morning timeframe. Winds may
increase to the Wind Advisory levels as the winds shift from the
east to northeast.

.Long term...

The trough is forecast to move to the south by Thursday evening.
The risk of heavy rainfall ends and the chance of rain reduces to
scattered showers. Winds shift from the north on Friday to the
west throughout the weekend as a gale (low pressure system) forms
well to the south of the territory. The risk of flash flooding is
not expected at this time.



Rough and choppy seas remain along the American Samoa coastal
waters due to a fresh to strong easterly breeze. Even though there
are no significant swell moving through the region, the wind
driven waves are high enough to produce surf within the High Surf
Advisory criteria through Thursday. The advisory is for the
eastern shores of all islands. As a trough moves south on
Thursday, winds will decrease to a moderate breeze (11-16 knots)
as winds are to shift from the northeast on Thursday, to north on
Friday, and from the west throughout the weekend.

A gale is to form well to the south of American Samoa late in the
week and this weekend. We are monitoring the possibility of high
surf on Saturday and Sunday.



A High Surf Advisory remains in effect.
A Small Craft Advisory remains in effect.