A few days ago I wrote an article about how Hurricane Nolo was threatening the Hawaiian Islands. It was the latest in a series of hurricanes to impact Hawaii during this El Nino-fueled Pacific basin season. Hurricane Nolo lingered for several days to the west of Hawaii and has now become a Typhoon. Here’s what happened.

How Hurricane Nolo Became Typhoon Nolo

As Nolo tracked westward, it crossed the International Date Line. That action did two things. It placed the storm a day ahead, and it entered the western Pacific Ocean. Because Nolo was still a Category 3 storm when it crossed the 180 degrees longitude, it maintained its status as a tropical cyclone. However, in the western Pacific Ocean, such storms are called typhoons rather than hurricanes.

During my three decades as a meteorology expert, people often ask me about the difference between a hurricane and typhoon. The answer is simply geography. “In the North Atlantic, central North Pacific, and eastern North Pacific, the term hurricane is used,” note the NOAA website . “The same type of disturbance in the Northwest Pacific is called a typhoon,” It continued. What about the South Pacific and Indian Ocean? In those regions the term “tropical cyclone” or “cyclone” is used.

Another interesting handoff also happens. The entire time that the Nolo was in the eastern-central Pacific, NOAA’s National Hurricane Center was providing updates and forecasts for the storm. The storm is now the responsibility of the Joint Typhoon Warning Center. What’s that? “The Joint Typhoon Warning Center (JTWC) is a joint United States Navy – United States Air Force command in Pearl Harbor, Hawaii…. Responsible for the issuing of tropical cyclone warnings in the North-West Pacific Ocean, South Pacific Ocean, and Indian Ocean for all branches of the U.S. Department of Defense and other U.S. government agencies,” stated the Cooperative Institute for Research in the Atmosphere website at Colorado State University. Because of the vastness of the oceans in its area of responsibility, they monitor about 89% of the tropical cyclone activity on Earth, continued the CIRA website.

What’s Next For Typhoon Nolo?

Nolo is expected to continue its westward motion and gradually weaken. It, however, will remain a threat worth watching in the coming days. It joins a crowded field in the western Pacific Ocean. JTWC is also monitoring Supertyphoon Choi-Wan and Tropical Storm Koguma.

How often does a date line crossing happen? According to a 2018 Yahoo article , a tropical cyclone crosses the international date line about every 1 to 2 years. We have gained greater confidence in this assessment in recent decades due to weather satellites.