Hanna Strengthens to a Hurricane Near South Texas

Former Tropical Storm Hanna strengthened into a hurricane near the coast of South Texas on Saturday morning.  At 8:00 a.m. EDT on Saturday the center of Hurricane Hanna was located at latitude 27.1°N and longitude 96.0°W which put it about 100 miles (160 km) east-southeast of Corpus Christi, Texas.  Hanna was moving toward the west at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (150 km/h).  The minimum surface pressure was 982 mb.

A Hurricane Warning was in effect for the portion of the coast from Port Mansfield to Mesquite Bay, Texas.  Tropical Storm Warnings were in effect for the portions of the coast from Barra de Mezquital, Mexico to Port Mansfield and from Mesquite Bay to High Island, Texas.

A NOAA aircraft detected winds to hurricane force in former Tropical Storm Hanna on Saturday morning and the National Hurricane Center upgraded Hanna to a hurricane.  The circulation around Hurricane Hanna was well organized.  A circular eye with a diameter of 25 miles (40 km) was at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Hanna.  Storms near the core were generating upper level divergence which was pumping mass away from the hurricane.  Winds to hurricane force extended out 25 miles (40 km) from the center of circulation.  Winds to tropical storm force extended out 90 miles (150 km) from the center.

Hurricane Hanna will move through an environment favorable for strengthening during the next few 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.  Hurricane Hanna will continue to intensify until it makes landfall on the coast of South Texas.

Hurricane Hanna will move south of a high pressure system that stretches across the southern U.S.  The high will steer Hanna a little to the south of due west.  On its anticipated track the center of Hurricane Hanna will make landfall on Padre Island later today.  The northern part of the eyewall will pass near Corpus Christi and that city could experience winds to hurricane force.  The southern part of the eyewall will pass near Port Mansfield which could also experience hurricane force winds.  The core of Hanna will pass north of Brownsville, but Brownsville, Harlingen and Mcallen could all experience winds to tropical storm force.

Easterly winds will blow water toward the coast of South Texas and they will cause a significant storm surge.  The storm surge could reach 6 to 9 feet (2 to 3 meters) near and just to the north of where the center makes landfall.  Hurricane Hanna will also drop heavy rain over South Texas.  Isolated locations could receive over a foot (0.3 meters) of rain and flash flooding is likely.

Elsewhere, Tropical Storm Gonazalo was quickly nearing Trinidad.  At 8:00 a.m. EDT on Saturday  the center of Tropical Storm Gonzalo was located at latitude 10.3°N and longitude 59.8°W which put it about 100 miles (160 km) east of Trinidad.  Gonzalo was moving toward the west at 18 m.p.h. (30 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 1009 mb.

Tropical Storm Warnings were in effect  for Tobago and Grenada.