When NASA's Aqua satellite passed over the eastern Pacific Ocean it looked at a newly developed tropical depression that would later strengthen into Tropical Storm Lester. Aqua analyzed the depression with an infrared eye and saw indications it was strengthening.
The Atmospheric Infrared Sounder or AIRS instrument aboard Aqua provided temperature data on Tropical Depression 13E on Aug. 24 at 4:17 p.m. EDT (2017 UTC). AIRS infrared data showed that the depression had some powerful thunderstorms with high cold cloud tops (as cold as -63F/-53C).
By 5 p.m. EDT the low pressure area was officially recognized as Tropical Depression 13E. The depression formed about 455 miles (730 miles) southwest of Manzanillo, Mexico. The depression strengthened into a tropical storm at 5 a.m. on Aug. 25.
NASA's Aqua satellite provided temperature data on Tropical Depression 13E on Aug. 24 at 4:17 p.m. EDT (2017 UTC) and strongest storms appear in purple, indicating coldest cloud tops. Credit: Credits: NASA JPL, Ed Olsen
On Aug. 25, the National Hurricane Center said the cloud pattern of Lester continues to gradually become better organized, with developing convective banding features surrounding a small central dense overcast and expanding upper-level outflow.
The National Hurricane Center (NHC) said at 11 a.m. EDT (1500 UTC), the center of Tropical Storm Lester was located near latitude 16.6 degrees north latitude and 112.5 degrees west longitude. That's about 465 miles south-southwest of the southern tip of Baja California, Mexico.
Lester was moving toward the west-northwest near 12 mph (19 kph) and a gradual turn toward the west is expected over the next 48 hours. Maximum sustained winds have increased to near 50 mph (85 kph) with higher gusts.
Infrared data from the AIRS instrument shows that the waters that lie ahead of Lester are at least 80 degrees Fahrenheit (26.6 degrees Celsius), warm enough to keep maintaining the storm's strength.
Continued strengthening is forecast during the next couple of days, and Lester is likely to become a hurricane on Friday, Aug. 26, according to NHC.
source: NASA/Goddard Space Flight Center