Area Forecast Discussion
Issued by NWS Pago Pago

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FXZS60 NSTU 240119

Area Forecast Discussion
National Weather Service Pago Pago  AS
219 PM SST Sun Jun 23 2019

.Discussion...IR satellite loop showing area of strong convection
with heavy rainfall in a line about 200 miles north of the Samoan
Islands. The latest satellite trends shows a slight southward
drop in the line during the past several hours. The biggest
forecast concerns tonight will be the winds and developing
potential for heavy rainfall into early Monday.

Satellite data shows the strong convection north of the islands,
firing in an compressing area of Theta-E while mid level qvectors
show strong convergence through the ridge of increased instability
and moisture. The latest NESDIS AHI QPE estimates from this area
of pcpn showing an estimated rainfall nearing one inch per hour.
The latest model trends suggests this area of moisture and
instability dropping south toward American Samoa tonight, while
qvector convergence shows a slight decrease in forcing. GFS and
ECMWF vertical moisture profiles show limited mstr in mid and
upper levels, while abundant low level moisture extends up toward
700mb. Overall based on current trends will mention scattered rain
showers into Monday while heaviest rainfall amounts should remain
north. Otherwise will continue to mention at least some chance for
rain showers through the upcoming week as weak troughing passes
east over the region. Rain chances really increase again next
weekend as mid and upper level moisture increases rapidly over the

Will keep southeast to east winds just under advisory criteria
into Monday, as vertical wind profiles and the latest PPG
sounding shows strongest winds in the mixed layer remaining
southeast to east around 25 kts.


.Marine...Current data showing winds and seas remaining in
advisory criteria across the Samoan Islands this evening through
Monday. The latest PacIOOS at Aunu`u shows wave heights around
10ft with periods around 7 seconds with peak periods around 8sec.
The latest Wave Watch III data shows significant wave heights
lingering between 9 to 12ft through Monday with periods
increasing little overnight. East trades this week will continue
rough seas around the islands, before a significant increase is
expected again during the upcoming weekend.



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



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