sentences:  Debby remained a tropical cyclone while crossing the North Atlantic Ocean and weakened to a tropical storm at 0600 UTC September 20.Debby was rapidly approaching the British Isles on September 20 shortly before it transitioned into an extratropical cyclone.The remains of Debby maintained plenty of intensity over northern Europe, and on September 21 it struck northern parts of Finland (where it was named storm Mauri) as one of the most powerful windstorms in the country's recorded history.