A Slow-moving Isaac Brings Flooding to Gulf States

Isaac – once a Category 1 hurricane and now a strong tropical storm with maximum sustained winds of 70 miles per hour (60 knots) – continues to create havoc across the Gulf Coast, from eastern Texas to Florida. While “only” reaching Category 1 on the Saffir-Simpson hurricane wind scale upon landfall on Aug. 28, Isaac is a slow mover, crawling along at only about six miles (10 kilometers) per hour. This slow movement is forecast to continue over the next 24 to 36 hours, bringing a prolonged threat of flooding to the northern Gulf Coast and south-central United States.

As seen in this infrared image from the Atmospheric Infrared Sounder (AIRS) instrument on NASA’s Aqua spacecraft, acquired at 2:41 p.m. CDT on Aug. 29, 2012, the large storm is still relatively well organized and is producing strong bands of thunderstorms. The broad area of purple in the image represents cloud-top temperatures colder than minus 63 degrees Fahrenheit (minus 52 degrees Celsius) around the center of the storm’s circulation. It is here that Isaac’s strongest storms and heaviest rainfall are now occurring.

According to the National Oceanic and Atmospheric Administration’s National Hurricane Center, strong bands of thunderstorms continue to develop over water in the storm’s eastern semicircle and southwest of the center. These strong rain bands are forecast to spread gradually to the west tonight across coastal southeastern Louisiana and southern Mississippi, including the New Orleans metropolitan area. The storm is expected to weaken to a tropical depression by Thursday night and a post-tropical remnant low-pressure system by Friday.

For more on NASA’s Atmospheric Infrared Sounder, visit: http://airs.jpl.nasa.gov/.