Saturday, October 18, 2014

Massive Waves Slam O'ahu Tonight and Build on Kauai through Sunday

Hurricane Ana is generating massive waves that are slamming the south shores of the Hawaiian Islands tonight. The highest waves are impacting the south and east coasts of O'ahu, Kauai and Ni'ihau. The National Data Buoy Center's buoy at Barber's Point, just west of Ewa Beach, O'ahu, reported a significant wave height of 9.8 ft (3 m) and building at 4:56 PM HST.

The significant wave height is the height from trough to crest of the highest one-third of the waves. This means the highest one-third of the waves at Barber's Point are at least 9.8 ft (3 m) high.

The National Weather Service offshore forecast for waters south of O'ahu predicts wind waves of 10 ft (3.05 m) and a SE swell of 12 ft (3.88 m) tonight.

Hurricane Ana is generating enormous waves that are pounding the south shore of O'ahu and Kauai this evening.
Base Map: National Data Buoy Center, Graphics: Hal Needham

However, the NOAA Tides and Currents tide gauge at nearby Honolulu is reporting storm surge levels less than 0.5 ft (15 cm). This is not surprising, however, as hurricanes passing near Hawaii typically generated enormous waves but relatively low storm surges.

Storm surge levels at Honolulu remain less than 0.5 ft (15 cm) high this evening, despite enormous surf pounding O'ahu's south shore. Storm surge in this image is the difference between actual water levels (red line) and predicted tide levels (blue line).
Source: NOAA Tides and Currents

As Ana moves NW, the center of circulation will pass dangerously close to Kauai and Ni'ihau. Expect surf to build along the south and east shores of those islands tonight and Sunday. The National Weather Service offshore forecast south of Kauai predicts a 12 ft (3.88 m) south swell on Sunday.

According to a wave model used by Swell Info, significant wave heights along south and east shores of Kauai and Ni'ihau should exceed 12 ft (3.88 m) on Sunday morning.

Significant wave heights are forecast to build tonight and Sunday morning on south and east shores of Kauai and Ni'ihau. This forecast is for 0800 HST Sunday morning.
Source: Swell Info. See animated model at:

Stay safe everyone and send me pics or descriptions if possible!
~Hurricane Hal

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