Kilo (2015)

Kilo formed as a tropical disturbance southeast of the Big Island of Hawaii in mid-August 2015 and became a tropical depression in the central North Pacific on 22 August 2015. It moved generally westward and then southwestward and northwestward, drifting slowly at times as steering currents weakened. After remaining weak and disorganized for several days, Kilo became a tropical storm on 26 August and reached hurricane strength on 29 August. The cyclone rapidly intensified late on 29 August and into 30 August as it approached the International Date Line, then crossed the Date Line on 1 September and continued westward into the western Pacific.

Kilo did not make any landfall on major populated islands while in the central Pacific basin covered by the report. The center passed about 35 miles north of Johnston Island late on 27–28 August, producing tropical-storm conditions there, but no reports of tropical-storm-force winds or impacts from the island were received. After crossing the Date Line, responsibility for warnings and forecasting passed to other agencies; the NHC/CPHC portion of the record contains no landfalls on U.S. territory.

Kilo’s maximum sustained winds reached 120 knots (about 138 mph) at its peak on 30 August, with a minimum central pressure of 940 millibars. At peak intensity it was a high-end Category 4 hurricane on the Saffir-Simpson scale. After peak, Kilo weakened slightly but remained a major hurricane for a period before moving into the western Pacific.

Measured storm surge and rainfall reports associated with Kilo in the central Pacific were minimal. No ship or land-based reports of tropical-storm-force or greater winds were recorded in the central Pacific portion of its track, and no specific storm surge heights or substantial rainfall totals at named cities or counties were reported in the NHC/CPHC portion of the record. Johnston Island experienced tropical-storm conditions when the center passed nearby, but no calibrated barometer or impact measurements from the island were received by the National Weather Service.

There were no reported deaths or damage attributed to Kilo in the central North Pacific. Noteworthy aspects of Kilo include its long track of over 4,000 statute miles from formation to its location near the western Kuril Islands and its rapid intensification to a Category 4 hurricane as it approached the Date Line. Kilo was part of an unusually active 2015 Pacific season (strong El Niño), and for a time was one of three concurrent major hurricanes in the Pacific—an unprecedented event east of the Date Line. Forecast track errors were generally better than recent averages at some lead times, but intensity forecasts underperformed because the system was slow to organize early and then intensified faster than anticipated.