Tropical Storm Alvin intensified over the Eastern North Pacific Ocean southwest of Mexico on Thursday.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Alvin was located at latitude 16.0°N and longitude 107.9°W which put the center about 305 miles (495 km) west-southwest of Manzanillo, Mexico.  Alvin was moving toward the northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 999 mb.

Tropical Storm Alvin intensified over the Eastern North Pacific Ocean southwest of Mexico on Thursday.  The inner end of a rainband wrapped around the western side of the center of Alvin’s circulation.  Other bands of showers and thunderstorms were revolving around the center of Tropical Storm Alvin.  Storms near the center of Alvin generated upper level divergence that pumped mass away from the tropical storm.  The removal of mass caused the surface pressure to decrease.

The area of tropical storm force winds increased in size when Tropical Storm Alvin intensified on Thursday.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Alvin’s circulation.

Tropical Storm Alvin will move into an environment that will become unfavorable for intensification during the next 24 hours.  Alvin will move over water where where the Sea Surface Temperatures are near 26°C.  It will move under the southeastern part of an upper level low over Baja California.  The upper level low will produce southwesterly winds that will blow toward the top of Alvin’s circulation.  Those winds will cause the vertical wind shear to increase on Friday.  The combination of cooler Sea Surface Temperatures and more vertical wind shear will cause Tropical Storm Alvin to start to weaken during the next 24 hours.

Tropical Storm Alvin will move around the southwestern part of a high pressure system over Mexico.  The high pressure system over Mexico and the upper level low over Baja California will steer Alvin toward the north-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Alvin will move parallel to the west coast of Mexico.