NASA views new Atlantic tropical depression in infrared

The eleventh tropical depression of the Atlantic Ocean formed early on September 28 over 400 miles southwest of Bermuda as NASA's Aqua satellite passed overhead and looked at the storm in infrared light.The Atmospheric Infrared Sounder or AIRS instrument that flies aboard NASA's Aqua satellite gathers data in infrared light that provides information about temperatures.

The colder the cloud top temperature, the higher the storms are in the troposphere (because the higher you go in the troposphere, the colder it gets). When storms get very high, cloud top temperatures get as cold or colder than -63 Fahrenheit/-53 Celsius, which is what AIRS data showed east and south of the center of newborn Tropical Depression 11 (TD11) September 28 at 623 UTC (2:23 a.m. EDT). Storms with cloud top temperatures that high have been shown to produce heavy rainfall.

At 11 a.m. EDT (1500 UTC), the center of Tropical Depression Eleven was located near latitude 27.8 North, longitude 69.6 West. That's about 425 miles (680 km) southwest of Bermuda. The depression was moving toward the west-northwest near 5 mph (7 kph) and the National Hurricane Center (NHC) forecasts a slow west-northwestward to northwestward motion during the next couple of days.

Maximum sustained winds were near 35 mph (55 kph) with higher gusts AND Strengthening is forecast. The NHC expects the depression to become a tropical storm later in the day.