Tropical Depression Eight Strengthens to Tropical Storm Hanna

Former Tropical Depression Eight strengthened to Tropical Storm Hanna on Thursday night and a Tropical Storm Warning was in effect for a large portion of the coast of Texas.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Hanna was located at latitude 26.2°N and longitude 91.4°W which put it about 385 miles (620 km) east-southeast of Corpus Christi, Texas.  Hanna was moving toward the west-northwest at 7 m.p.h. (11 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 1002 mb.

A Tropical Storm Warning was in effect for the portion of the coast from the Mouth of the Rio Grande River to San Luis Pass, Texas.  A Tropical Storm Watch was in effect for the portion of the coast from San Luis Pass to High Island, Texas.

A NOAA aircraft detected winds to tropical storm force in former Tropical Depression Eight on Thursday night and the National Hurricane Center upgraded the system to Tropical Storm Hanna.  The surface pressure was decreasing and Tropical Storm Hanna was exhibiting greater organization.  A band of thunderstorms was wrapping around the southern and eastern sides of the center of circulation.  Thunderstorms were forming in other bands the were revolving around the center of circulation.  Storms near the center began to generate upper level divergence which was pumping mass away from the tropical storm.  The removal of mass allowed the surface pressure to decrease.  Winds to tropical storm force extended out 35 miles (55 km) from the center in the eastern quadrant of Tropical Storm Hanna.  Winds in the other parts of Hanna were blowing at less than tropical storm force.

Tropical Storm Hanna will move through an environment favorable for intensification during the next 36 hours.  Hanna will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Hanna will continue to intensify and there is a chance it could strengthen into a hurricane.

Tropical Storm Hanna will move south of a high pressure system that extends from the Atlantic Ocean across the southern U.S.  The high will steer Hanna slowly toward the west.  On its anticipated track Tropical Storm Hanna will approach the coast of Texas near Corpus Christi on Saturday.  Hanna could be a strong tropical storm or a hurricane when it reaches the coast.

Elsewhere, Tropical Storm Gonzalo continued to churn toward the Windward Islands.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Gonzalo was located at latitude 9.9°N and longitude 50.6°W which put it about 730 miles (1170 km) east of the southern Windward Islands.  Gonzalo was moving toward the west at 14 m.p.h. (22 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. (120km/h).  The minimum surface pressure was 1000 mb.

A Hurricane Watch was in effect for Barbados and St. Vincent and the Grenadines.  A Tropical Storm Watch was in effect for Tobago and Grenada.