 Early on July 22 , a tropical wave and associated low @-@ pressure area emerged off the western coast of Africa . Based on satellite data , the wave was upgraded to a tropical depression at 18 : 00 UTC on July 23 while located about 175 mi ( 280 km ) south of the Cape Verde Islands , and further intensified into Tropical Storm Dorian by 06 : 00 UTC the following day . The storm tracked swiftly west @-@ northwest over warm ocean temperatures and within an environment of low wind shear initially , allowing it to attain peak winds of 60 mph ( 95 km / h ) by July 25 . However , the entrainment of drier mid @-@ level air and cooler ocean waters caused a weakening trend . 
