How was Hurricane Ophelia, which hit Ireland, able to form that far north in the cool Atlantic?

Dear Tom,
How was Hurricane Ophelia, which hit Ireland, able to form that far north in the cool Atlantic?
— Monica Piszczek, Paw Paw, Ill.
Dear Monica,
Hurricane Ophelia’s formation in the still-warm central Atlantic was not all that unusual. What was unusual was that the storm retained tropical characteristics so far north, finally becoming a very strong post-tropical cyclone about 250 miles southwest of Ireland. Hurricane remnants have frequently hit the British Isles and western Europe with strong winds and high waves.
In October 1996, the remnants of Hurricane Lili — packing 90 mph winds and 35-foot waves — damaged portions of England. In 1961, Hurricane Debbie hit Northern Ireland with gusts up to 114 mph. And in 2006, the remains of Hurricane Gordon hit Cornwall, England, with winds up to 81 mph.