Power of Les Suetes winds on display in Cape Breton Highlands

Powerful winds in Cape Breton’s Inverness County toppled a transport truck in the vicinity of Saint Joseph du Moine. (COURTESY BERNICE LEBLANC-AUCOIN)

While it has been gusty over the last 24 hours in much of the Maritimes, powerful winds in Cape Breton’s Inverness County toppled a transport truck in the vicinity of Saint Joseph du Moine.

A reliable source for winds in the area put gusts at 145 km/h and the weather station located at Grand Etang in Cape Breton confirms gusts of near that speed with a report of 142 km/h at 9 a.m. Wednesday.

The extreme gusts eased into the early afternoon. Further diminishment of the winds is forecast for Wednesday evening and overnight. During a strong winter storm, local gusts in this area have been observed as upwards of 200 km/h.

So what’s the cause for such an outlier in wind speeds for this small corner of the Maritimes? Topography. The orientation of the Cape Breton Highlands makes this area of the Maritimes vulnerable to a unique funneling effect called a foehn wind.

A foehn wind occurs on the leeward side (the side that is not facing into the wind) of elevated terrain. As air is forced upward on the windward side of a mountain, moisture is condensed out in the form of rain. The drier air then descends on the leeward side and since it is now more dense (have lost moisture content) accelerates greatly in speed. The topography is also favourable for generating an increase in turbulence, which can mix down stronger winds to the surface that are normally held aloft in the passing weather system.

This phenomena in Cape Breton is termed a “Les Suetes” wind with the term “Suetes” an Acadian French contraction of “sud est” or “south east” which is the common wind direction needed to produce this effect.

Areas in Canada that see similar wind effects include the Wreckhouse area in southwestern Newfoundland and the Crowsnest Pass along the southern border of British Columbia and Alberta.