Champi quickly formed in the last 24 hours and is forecast to further develop, evolving from a tropical depression to a tropical storm and now forecast to become a typhoon soon. With typhoon conditions possible, authorities in the U.S. have issued a Typhoon Watch for Guam and the nearby islands of Rota, Tinian, and Saipan in the Marianas. A Typhoon Watch means that typhoon conditions, including winds of 74 mph or more, are possible within the next 48 hours.

A typhoon is a tropical cyclone identical in every way but name to a hurricane; west of the International Date Line, these tropical cyclones are called typhoons while east of the International Date Line, they’re called hurricanes.

As of the latest advisory from the National Weather Service in Tiyan, Guam, the center of the storm was located about 295 miles west-northwest of Ujelang, about 300 miles north-northwest of Pohnpei, about 420 miles northeast of Chuuk, about 795 miles east-southeast of Saipan, and about 825 miles east of Guam. Maximum sustained winds of the storm are at 40 mph, making it a minimal tropical storm for now as it moves west at 12 mph.

The National Weather Service says Champi should continue heading to the west through Sunday, with a slight increase in forward speed. While it’s heading west, it is also expected to intensify. The forecast calls for intensification through Sunday, with Champi expected to become a typhoon on Saturday.

Guam and Saipan are no stranger to typhoons, including this season. On July 6, a category-5 storm, Super Typhoon Bavi, blasted through the islands with 180- mph winds, moving directly over Rota while bringing severe impacts to Saipan and Guam too. Bavi eventually claimed over 22 lives and created damages in excess of $140 million.