though only five were killed Killing directly , the us $ 1.77 billion ( equivalent to $ billion in ) in damage Damaging accrued by frederic made it Causation the atlantic basin 's costliest tropical cyclone on record Recording at the time .

frederic developed Coming_to_be from a tropical depression south of the cape verde islands on august 28 , 1979 .

over the united states , frederic weakened Cause_change_of_strength for a final time before becoming Becoming extratropical in pennsylvania on september 14 and dissipating Dispersal the next day .