Strong Winds and High Seas around the Samoan Islands
Wave observations from the Aunu’u site just to the east of American Samoa, above, show waves exceeding 12 feet starting late in the day on 22 September and persisting through the weekend into the 25th. The National Weather Service office in Pago Pago issued High Surf Warnings during this event
ASZ001>004-251915-Tutuila-Aunuu-Manua-Swains Island-Rose Atoll-705 PM SST Sun Sep 24 2023
...HIGH SURF WARNING NOW IN EFFECT UNTIL MONDAY...
WHAT...Surf of 15 to 18 feet
WHERE...East and south shores
WHEN...Through Monday
IMPACTS...Expect ocean water occasionally sweeping across beaches,very strong breaking waves, and strong longshore and potentially deadly rip currents. Some strong coastal erosion is likely. Very large waves may bring some ocean debris onto roadways, impact small harbors, and make navigating the harbor channel dangerous.
PRECAUTIONARY/PREPAREDNESS ACTIONS...Residents in vulnerable locations may experience flooding. Some roads in vulnerable, low-lying areas may be closed from floodwaters. Stay tuned to local officials for any road closures or evacuations. Anyone in low-lying and vulnerable areas could be swept out to sea and face significant injury or death.MetopB and MetopC Advanced Scatterometer plots (taken from this website), below, show a large region of strong (20-25 knot) east-southeast winds to the west and south of Samoa and American Samoa.
GOES-18 Derived Motion Wind vectors, below, similarly show a large region of 20-25 knot winds to the east and south of the Samoan Islands. These winds are helping to force the wave action.
Altimetry from satellites can also be used to determine wave heights, and a plot (also from this website, then click on ‘Altimeter’) is shown below. It is difficult to compare these values to the buoy values above; altimetry plots show the Significant Wave Height, namely the mean wave height of the highest 1/3 of all waves. The single swath shown below has Significant Wave Heights between 9 and 11 feet, at 1343 UTC on 23 September 2023.
