 A tropical wave emerged from the west coast of Africa on August 30 and tracked westward across the Atlantic Ocean , maintaining a vigorous area of convection along the wave axis . By September 1 most of the deep convection had been stripped away by southwesterly wind shear . Despite this , the wave remained well @-@ defined as it continued west @-@ northwest . The wave split into two pieces ; the northern portion passed between the Leeward Islands and Hurricane Maria on September 3 , while the southern portion moved into the Caribbean Sea . On September 4 , the northern portion of the wave began to interact with an upper @-@ level low pressure system and an elongated trough that was located between Bermuda and the Leeward Islands — the same trough which contributed to the development of Hurricane Ophelia . As a result of the low wind shear , convection redeveloped and organized along the wave axis . Convective banding formed around a broad surface low . It is estimated that the system developed into a tropical depression at 1800 UTC on September 5 . At the time it was located approximately 350 miles ( 560 km ) to the south @-@ southwest of Bermuda . 
