National Weather Service United States Department of Commerce

Sunday Brings Heat Relief For Some; Flash Flood Threat Along Cold Front

A cold front shifting across the Central Plains, Midwest, Great Lakes and Northeast on Sunday will bring some relief from the heat with cooler and drier air. Excessive heat holds Sunday roughly south of I-70. Heavy rain from thunderstorms along the front may bring flash flooding. Read More >

FXZS60 NSTU 210147

Area Forecast Discussion
National Weather Service Pago Pago AS
247 PM SST Sat Jul 20 2019

.Discussion...Current observation trends continue to show limited
precipitation occurring over the Samoan Island this afternoon with
the main areas of rain remaining north and south of the region.
The main forecast concern this package will be chances for rain
along with increasing winds into the middle of next week.

The current IR satellite is showing rapidly cooling cloud top
temps near Fiji and well northeast of the islands this afternoon,
in ridge of increasing moisture and instability and mid lvl
qvector convergence. Short-term model trends show these bands of
most unstable air and most persistent rainfall, to remain north
and south of American Samoa this evening. Mid level streamlines
and moisture plumes would also suggest limited pcpn chances for
the region through Sunday.

Vertical moisture profile data shows an increase in mid and upper
level moisture developing over the islands Tuesday night and
Wednesday. Significant moisture then extends through the column
Thursday and Friday, increasing chances for rain for American
Samoa during the second half of the work week.

Overall will continue with limited rainfall tonight through
Monday and Tuesday, before increasing the chance of rain by mid


.Marine...Current marine observations show winds and waves are
under advisory criteria this afternoon. PacIOOS and Wave Watch III
data, shows winds and waves to remain below advisory criteria
into the beginning of the upcoming work week. However, winds are
expected to slowly increase from southeast by the middle of next
week, as speeds increase to between 20 and 25 kts with higher.