Warm waters allowed Preventing_or_letting Hellen to rapidly intensify Cause_change_of_strength while passing Motion_directional south of the Comoros , with a well-defined eye forming Coming_to_be in the middle of the thunderstorms .

Warm onshore winds , caused Causation by a storm Catastrophe track close to the shore , allowed Preventing_or_letting precipitation to change Change to sleet and rain in central and eastern New England .

Warm waters and favorable outflow allowed Preventing_or_letting the storm to quickly intensify Cause_change_of_strength to peak maximum sustained winds of 175 km/h ( 110 mph ) on May 15 .