Hurricanes are considered by many as beasts unique to southern latitudes; yet on average, two or three tropical cyclones affect Canada and the adjacent offshore waters each year. These systems, which are leaving the warm tropical waters and are normally in the decay stage of their life-cycle, still possess an extraordinary amount of energy and pose a unique and difficult prediction problem. In fact, perhaps the worst natural disaster in Canadian history occurred as a result of a hurricane that killed as many as 4000 mariners off the coast of Newfoundland in 1775. While the most famous hurricane in modern days is "Hazel", that killed 83 in Southern Ontario in October 1954, the "Saxby Gale" likely resulted in as much or more death and damage when it struck New England and the Maritime Provinces in 1869. This storm was made famous by the almost one year prediction of Lt. S.M. Saxby of the Royal Navy that a storm of unusual violence with an extraordinary rise in tide would strike the Earth on the morning of 05 October 1869.
Tropical cyclones moving over colder waters into middle and northern latitudes are usually accelerating under the influence of the mid-latitude westerly circulation. This acceleration is accompanied by a shift in the low-level wind pattern, with the strongest winds observed along and to the right of the storm track. The precipitation pattern also shifts to an asymmetrical distribution similar to that of an extra-tropical storm, with the bulk of precipitation along and to the left of the storm track. The strong winds, heavy rains, storm surge and high surf are seldom as intense as when the tropical cyclone was further south. Nevertheless, there remains a risk unique to the middle latitudes— that of a rapid re-intensification as a result of the interaction with a baroclinic system. Indeed, "Hazel" was such a hybrid storm, with extremely heavy rainfalls of over 200mm in less than one day that caused severe flooding. As it turns out, our examination of the meteorological situation from a forensic study of the "Saxby Gale" suggests that it too was a hybrid re-intensification like "Hazel". We will use this comparison to develop a conceptual model that describes the meteorological set-up associated with this rare and extreme event.