Examples of mountain induced winds in Atlantic Canada

Although relatively low in comparison with the mountains of Western Canada, the mountains in Atlantic Canada can induce hurricane force gusts in down slope winds.

The “Suête” winds in Cape Breton are named from a corruption of the Acadian French term for Sud-Est.

A brief description of some of the damage effects is presented to highlight the severity of conditions that can be produced by mountains of only 400 m elevation.

The phenomenon appears to be driven by a combination of strong cross barrier (Southeast) winds through a significant depth with a significant inversion above the mountain top, conditions which typically occur ahead of an approaching warm front.

The strength of the resulting wind gusts relates well with the maximum low level winds in the Canadian GEM model, which along with surface isobaric and 850 mb height patterns and prog soundings are the main source of guidance used to predict these events. Similar, and often stronger, gusts are experienced in South-western Newfoundland in the well named Wreckhouse area, where trains have been blown off rails and trucks blown over.

Examples are also given occurrences of down slope winds in the opposite direction giving strong gusts on the lee side of the mountains following the passage of a cold front where the cold air is shallow and topped with a significant inversion. This is referred to by forecasters as a “reversed Suête .”