Former Tropical Depression Thirteen-E strengthened to Tropical Storm Lester south of Mexico on Friday morning and the government of Mexico issued a Tropical Storm Warning for a portion of the coast. At 8:00 a.m. EDT on Friday the center of Tropical Storm Lester was located at latitude 13.4°N and longitude 96.1°W which put it about 160 miles (255 km) south of Puerto Angel, Mexico. Lester was moving toward the northwest at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1005 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Punta Maldonado to Zihuatanejo, Mexico. The Tropical Storm Warning included Acapulco. A Tropical Storm Watch was in effect for the portion of the coast from Punta Maldonado to Laguna de Chacahua, Mexico. A Tropical Storm Watch was in effect from Zihuatanejo to Lazaro Cardenas, Mexico.

The circulation around former Tropical Depression Thirteen-E strengthened on Friday morning and the National Hurricane Center upgraded it to Tropical Storm Lester. Even though former Tropical Depression Thirteen-E strengthened to Tropical Storm Lester, the distribution of thunderstorms continued to be asymmetrical. Most of the thunderstorms were occurring in bands in the western half of Lester’s circulation. Bands in the eastern half of the circulation consisted primarily of showers and lower clouds. Storms near the center of circulation generated upper level divergence that pumped mass away to the west of the tropical storm. Winds to tropical storm force extended out 45 miles (75 km) in the southern half of Lester’s circulation. The winds in the northern half of the circulation were blowing at less than tropical storm force.

Tropical Storm Lester will move through an environment somewhat favorable for intensification during the next 36 hours. Lester will move over water where the Sea Surface Temperatures are near 30˚C. It will move under the southern side of an upper level ridge over Mexico. The upper level ridge will produce easterly winds that will blow toward the top of the tropical depression. Those winds will cause vertical wind shear and the wind shear will inhibit intensification. Tropical Storm Lester likely to strengthen gradually during the next 36 hours.

Tropical Storm Lester will move around the southwestern part of a high pressure system that extends over Mexico. The high pressure system will steer Lester toward the northwest during the next 36 hours. On its anticipated track Tropical Storm Lester will approach the southwest coast of Mexico on Saturday morning. Lester will bring gusty winds and locally heavy rain to Guerrero. Heavy rain could cause flash floods in some locations.