NDBC’s Observations Associated with Hurricane Iniki – September 1992

The deadliest and costliest hurricane to affect Hawai’i (Blake et al. 2007) and one of the deadliest and costliest US hurricanes of the 1990s (http://www.pricip.org/ea-portal/web/guest/home), Hurricane Iniki passed within 300¹ nautical miles (nm) of four buoys operated by NDBC and one Tropical Ocean Global Atmosphere (TOGA, now Tropical Atmosphere Ocean (TAO² ), see http://tao.noaa.gov/) buoy (see Figure 1). During the passage of Iniki, three of the NDBC buoys set extreme records for the month of September or for the Period of Record (PoR) for reported winds or seas. All NDBC buoys were 6-m NOMAD hulls with anemometers at 5 meters above the ocean surface and use eight-minute averages for wind speed taken near the top of each hour. The TOGA buoy is toroid hull with the anemometer about 4 meters above the ocean surface and speeds are averaged over one-minute period taken near the top of the hour. TOGA buoys do not make wave measurements.

Iniki’s track is taken from the Central Pacific Hurricane Center’s Archives (http://www.prh.noaa.gov/cphc/summaries/1992.php#Iniki). Closest Points of Approach (CPA) are interpolated at one-hour positions from the 6 or 3-hourly CPHC track points.

Iniki’s CPA to the TOGA buoy, 51006, occurred on 06 September 1992 at 1800 UTC about 192 nm to the north with peak wind speeds of about 11 m/s on 7 September (see Figure 2). Three days later Iniki’s CPA with NDBC buoy 51004 occurred on 09 September 1992 at 1600 UTC approximately 260 nm to the south with peak sustained winds also about 11 m/s (Figure 3). No extreme records were set on either buoy given the distance and still strengthening character of Iniki during that time.

As Iniki passed about 114 nm southwest of 51002 on 11 September 1992, at 0300 UTC, that buoy reported several records (Figure 4) for September (PoR 1984-2007):

• Lowest Sea-Level Pressure for September: 1003.2 hPa,
• Highest Sustained Wind Speed for September: 31.9 knots (16.41 m/s),
• Highest Gust for September: 38.1 knots (19.6 m/s), and
• Highest Significant Wave Height for September: 6.0 meters (19.69 feet).

Iniki would pass closest to 51003, 41 nm to the east on 11 September 1992 at 1600 UTC, as it approached peak intensity of 125 knots at 1800 UTC. Reports (Figure 5) set records that stand through the PoR, 1984-2007:

• Lowest Sea-Level Pressure: 996.5 hPa,
• Highest Sustained Wind Speed: 19.39 m/s (37.7 knots), and
• Highest Gusts: 24.13 m/s (46.9 knots).

In addition, 51003 reported the Highest Significant Wave Height for September: 5.5 meters (18.0 feet).

After passing over the island of Kauai, Iniki passed about 159 nm to the east of 51001. Although weakening, it remained a Category 3 hurricane resulting in 51001 reporting (Figure 6) the Lowest Sea-level Pressure 1005.5 hPa for September (PoR 1981-2007).

Reference:

Blake, E.S., E.N. Rappaport, and C.W. Landsea, April 2007, The Deadliest, Costliest, And Most Intense United States Tropical Cyclones From 1851 To 2006 (And Other Frequently Requested Hurricane Facts), NOAA Technical Memorandum NWS TPC-5, National Hurricane Center, Miami FL, p. 20.

1 Tropical cyclone warning centers request observations from ships within 300 nm of a tropical cyclone center.
2 NDBC assumed operational responsibility for TAO in 2006

Figure 1: NDBC and TOGA buoys within 300 nm of Iniki's Track

Figure 2: 1-minute wind speed at TOGA buoy 51006. Anemometer height: 4 meters.

Figure 3: Meteorological Reports for 51004

Figure 4: Meteorological reports for 51002

Figure 5: Meteorological Reports for 51003

Figure 6: Meteorological Reports for 51001