Tropical Storm Maria strengthened quickly on Wednesday and it brought gusty winds and heavy rain to Guam. The weather station at Andersen Air Force Base on Guam reported sustained winds to 44 m.p.h. (71 km/h) and wind gusts to 72 m.p.h. (116 km/h). At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Maria was located at latitude 13.9°N and longitude 144.7°E which put it about 5 miles (10 km/h) south of Andersen Air Force Base. Maria was moving toward the north-northwest at 11 m.p.h. (17 km/h). The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h). The minimum surface pressure was 987 mb. Tropical Storm Warnings remained in effect for Guam and Rota. Tropical Storm Watches were in effect for Saipan and Tinian.
The circulation of Tropical Storm Maria organized quickly on Wednesday. A tight center of circulation contracted at the center of Maria. A partial ring of thunderstorms formed on the east side of the center. Numerous bands of showers and thunderstorms were revolving around the core of the circulation. Storms around the core generated well developed upper level divergence which pumped mass away in all directions from the tropical storm. Winds to tropical storm force extended out about 95 miles (155 km) from the center of circulation.
Tropical Storm Maria will move through an environment very favorable for intensification. Maria will move over water where the Sea Surface Temperature is near 30°C. Tropical Storm Maria will move under the western portion of an upper level ridge where the upper level winds are weak. There will little vertical wind shear. Upper level lows east and west of the ridge will enhance the upper level divergence. Tropical Storm Maria will strengthen into a typhoon on Thursday. Maria could intensify rapidly and it is likely to become the equivalent of a major hurricane.
Tropical Storm Maria was moving around the western end of a subtropical ridge which was steering Maria toward the north-northwest. The ridge is forecast to steer Maria toward the northwest during the next few days. On its anticipated track Tropical Storm Maria will move away from the Marianas and toward the Ryukyu Islands. Tropical Storm Maria will continue to cause gusty winds and drop locally heavy rain on the southern Marianas for a few more hours. Conditions will improve on Thursday when Maria moves away the Marianas.