On May 17, a disturbance associated with a low presure area, and the ITCZ formed southeast of Guam. Late on May 20, the JTWC issued a TCFA on the system because of improving equator-ward outflow. Early on May 21, the JMA upgraded the low-pressure area to a tropical depression, and the JTWC also upgraded the system to a tropical depression later.
Early on May 22, the JMA upgraded the system to a tropical storm and named it Sanvu, as the tropical depression intensified even as it moved northwestward away from coastal waters of the Marianas.
As of 5pm yesterday, Tropical Storm Sanvu was still churning northwestward at 12 miles per hour with maximum sustained winds near 85 km/hr (45 knots) with higher gusts. At that time, Sanvu’s center was 130 miles west-northwest of Guam, 155 miles west of Rota, 190 miles west-southwest of Tinian, and 200 miles southwest of Saipan. Tropical Storm Force Winds (62-117 km/hr) extend outward up to 185 kilometers (100 nautical miles) from the center. Sanvu is an average-sized tropical cyclone with a diameter of 480 kilometers (260 nautical miles).
A tropical storm warning at that time was still in effect for Guam and Rota, while a tropical storm watch was also still in effect for Tinian and Saipan. The storm brought numerous showers and isolated thunderstorms in the morning until last night, Tuesday. NWS said that scattered showers and isolated thunderstorms will linger into Wednesday night in the region.
Sanvu is expected to continue moving NW for the next 12 to 24 hours, before turning more northerly on Friday and recurving NNE to NE-ward on Saturday. On the forecast track, the core of Sanvu will pass very close to Iwo To by early Saturday morning. The system is forecast to continue intensifying and will likely become a Typhoon on Thursday.