Malia — 2015

A low-pressure trough in the central North Pacific organized into a tropical depression on 18 September 2015 about 1,050 nautical miles west‑southwest of Honolulu. The system moved generally northward and became Tropical Storm Malia on 21 September while passing near the northwest Hawaiian Islands. Malia reached its peak on 21 September and then moved northwest, weakened as wind shear displaced its thunderstorms, became a post‑tropical remnant low on 22 September, and was absorbed by an extratropical low on 23 September. Malia did not make a direct landfall on any of the main Hawaiian Islands. Its closest approach to land was near the small northwest Hawaiian Island of Laysan: at about 1500 UTC 21 September the center passed roughly 20 nautical miles east of Laysan while the system had tropical‑storm‑force winds. Tropical storm watches and warnings were issued for parts of the Papahānaumokuākea Marine National Monument; warnings were cancelled when the storm tracked safely to the east of most islands. The storm’s maximum sustained winds were estimated at 45 knots (about 52 mph) at 1200 UTC 21 September, with a minimum central pressure estimated near 992 millibars. At peak intensity Malia was a moderate tropical storm (not a hurricane). No storm surge reports or significant rainfall totals associated with Malia were documented in the report for populated Hawaiian islands. Observations noted wind measurements from satellite scatterometer data indicating a swath of roughly 40‑knot winds with embedded 45‑knot winds, but there were no ship or station reports of tropical‑storm‑force winds on land in the northwest Hawaiian Islands. There were no reports of damage or casualties attributed to Malia. The storm caused minimal impacts because its strongest winds and convection remained over water and it passed well east of most island facilities. Notable aspects included relatively good advance notice of formation in the Tropical Weather Outlooks and generally good intensity forecasts. Track forecasts were less accurate than the recent 5‑year average because the low‑level center was shallow and difficult to locate, producing large spreads among model track guidance.