Hurricane Nolo intensifies to Category 3, poised to become a typhoon

Hurricane Nolo has rapidly intensified into a major Category 3 storm in the remote Pacific Ocean, packing winds of 115 mph as it marches toward the International Date Line.

By Sunday, the storm is expected to cross the 180-degree longitude line that separates the Central and Western Pacific basins. When it does, meteorologists say it will undergo a geographical rebrand, changing its title from Hurricane Nolo to Typhoon Nolo.

The National Hurricane Center reported on Saturday that Nolo was churning about 210 miles south-southwest of Maro Reef, moving westward at 17 mph.

While the storm poses no threat to Hawaii's populated islands, a tropical storm warning has been issued for the Papahanaumokuakea Marine National Monument. The massive, federally protected marine reserve of islands, seamounts, and coral reefs stretches from Maro Reef to Lisianski Island. Forecasters warned that large ocean swells associated with Nolo are likely to flood low-lying, uninhabited atolls in the area.

Crossing the date line

The transition from a hurricane to a typhoon is entirely a matter of geography, not a change in the storm's physical structure. Hurricanes and typhoons are the exact same weather phenomenon; the only difference is where they are located on the global map.

Once Nolo crosses 180 degrees longitude, it enters the Western Pacific basin. Under the rules of the World Meteorological Organization, the storm will keep its assigned name. However, as long as its sustained winds remain above the 74 mph threshold, it will officially be classified as Typhoon Nolo. Should its winds strengthen even further to exceed 150 mph, it will earn the designation of a Super Typhoon.

The geographical crossover also triggers a shift in scientific oversight. Official tracking and forecasting duties will hand over from the Central Pacific Hurricane Center to the Japan Meteorological Agency and the US Joint Typhoon Warning Center, which monitor the Western Pacific.

Such crossovers are rare but not unprecedented. Hurricane Dora made the same leap in August 2023, eventually becoming Typhoon Dora. Other historical examples include Hurricane Genevieve in 2014 and Hurricane Ioke in 2006.

Nolo's erratic journey

Nolo has had an unstable week in the Pacific. It first skirted past Hawaii's main population centres as a hurricane a week ago, before losing steam and weakening into a tropical storm. It then spent several days drifting westward over open waters before rapidly re-strengthening back into a hurricane on Friday.

Meanwhile, forecasters are also tracking Hurricane Rachel, a Category 1 storm heading westward away from the west coast of Mexico. Although Rachel is moving out to sea, the National Hurricane Center warned that it is generating dangerous coastal swells that will affect west-central Mexico and the Baja California Peninsula.