The potential impacts of Tropical Storm Calvin prompted the issuance of a Tropical Storm Watch for Hawaii. At 11:00 a.m. EDT on Monday the center of Tropical Storm Calvin was located at latitude 16.8°N and longitude 141.4°W which put it about 920 miles (1480 km) east of Hilo, Hawaii. Calvin was moving toward the west at 18 m.p.h. (30 km/h). The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 1000 mb.

A Tropical Storm Watch was in effect for Hawaii County.

The U.S. Central Pacific Hurricane Center issued a Tropical Storm Watch for Hawaii County on Monday morning because of the potential effects of Tropical Storm Calvin. Former Hurricane Calvin weakened to a tropical storm on Sunday as it moved over cooler water east of Hawaii. Tropical Storm Calvin moved over water where the Sea Surface Temperatures were near 24˚C. Less energy was transported into the atmosphere from the cooler water and many of the thunderstorms in Calvin’s circulation dissipated. The bands revolving around the center of Tropical Storm Calvin consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 105 miles (165 km) in the northern side of Calvin’s circulation. Winds to tropical storm force extended out 60 miles (95 km) in the southern side of the circulation.

Tropical Storm Calvin will move through an environment that will be mostly unfavorable for intensification during the next 24 hours. Calvin will move over water where the Sea Surface Temperatures are near 25˚C. It will move through a region where then upper level winds that are weak and there will be little vertical wind shear. Tropical Storm Calvin could continue to weaken during the next 24 hours because of the cooler water even though there will be little vertical wind shear. Calvin will move over slightly warmer water when it gets closer to Hawaii.

Tropical Storm Calvin will move around the southern part of a subtropical high pressure system over the Eastern and Central Pacific Ocean. The high pressure system will steer Calvin toward the west during the next several days. On its anticipated track, Tropical Storm Calvin will move near Hawaii on Tuesday night. Calvin could still be a tropical storm when it approaches Hawaii. Tropical Storm Calvin will bring gusty winds and locally heavy rain to Hawaii on Tuesday night and Wednesday.