https://phys.org/news/2018-10-nasa-bulk-tropical-storm-leslie.html

Infrared satellite data captured at 2:10 a.m. EDT (0610 UTC) on Oct. 1 from the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA's Aqua satellite revealed strongest storms with the coldest cloud top temperatures northwest of Leslie's center.  MODIS found coldest cloud tops had temperatures near minus 63 degrees Fahrenheit (minus 53 degrees Celsius). NASA research has found that cloud top temperatures that cold have the capability to generate heavy rainfall.

At 11 a.m. EDT, the National Hurricane Center or NHC noted, "Leslie is gradually becoming better organized.  A large band of deep convection exists on the west side of the circulation and some fragmented bands are beginning to form on the east side.  Overall, Leslie appears more symmetric than it has been during the past couple of days due to a decrease in wind shear."