 Upon becoming a depression on August 10 , the forward movement of the storm shifted to the northwest in response to an approaching trough off the Eastern United States and an elongated subtropical ridge to the south . The depression intensified into a tropical storm at 1800 UTC on August 11 ; however , operationally it was not upgraded until a reconnaissance mission by the hurricane hunters found flight @-@ level winds of 50 mph ( 80 km / h ) . The storm tracked towards Bermuda along a trough of low pressure in the Atlantic Ocean . 
