There’s no vember like November
Cape Breton Weather
October’s high-energy weather regime continued right through November. A nearly continuous succession of storms raced across the Maritimes, producing precipitation 24 of the month’s 30 days. Surges of cold air on Nov. 22/23 brought midwinter wind chills and snow squalls, and the month ended with a monster nor’easter.
Certainly, the big story in all this commotion was the wind. Grand Étang experienced gusts to 80 km/h or higher on half of the days Nov. 1-24. On 7 of those days, it reached or exceeded 100 km/h. Two days saw gusts to 140 and 144. St. Joseph du Moine recorded the month’s strongest, registering 164 km/h (102 mph!) on Nov. 10.
The map shows peak gusts recorded during the passage of three weather systems Nov. 10-16. This chart is remarkable, in part, because of the great number of reports. Seven sites are Environment Canada’s, but most of the other 40 are amateur weather stations, members of the Cape Breton Mesonet managed by Jonathan Buffett. As you can see, they provide us a wealth of detail about local conditions.
Each of the 3 storm centres between the 10th and the 16th approached from the southwest, producing intense southeasterly “Les Suêtes” gusts from Bay St. Lawrence south to St. Joseph du Moine. Once each storm centre passed to our north or east, its trailing westerlies swept across Cape Breton, generating a second period of extreme winds. The strongest winds at North Shore (114 km/h), Cape North (108), Henry Island (135) and at most locales south of the Highlands occurred in the west or northwest flow, not in Les Suêtes. Bay St. Lawrence and Henry Island were the champion switch-hitters in this 6-day wind fest, each measuring southeasterly winds to 135 and northwesterlies to 120 km/h!
Notice the large local variations in the gust speeds. Most impressive is the contrast between Henry Island, which is completely exposed to the wind, and Port Hood which is somewhat protected. Lighter winds in central Cape Breton and sites like Ingonish also show the Highlands’ sheltering influence, although a narrow zone of gusts over 90 threaded its way from Estmere to Iona and Ben Eoin.
Low-lying sites ringing Cape Breton at Hart Island, East Point PEI, and Îles de-la-madeleine all registered peak gusts at or slightly over 100 km/h during this period. On the other hand, instruments located above the steep shorelines of Henry Island, St. Paul Island, and Port-aux-basques all recorded values in the 130’s. Rough topography, which we generally think of as reducing wind speeds, can funnel wind flow and create turbulence that actually enhances wind speeds locally.
After November 16, the three-digit wind gusts declared a momentary truce, and a brief but intense arctic blast froze our attention. At sunrise on the 22nd, Sydney’s temperature was -2, exactly normal for that day and time. However, instead of rising with the sun, the mercury fell all day, reaching -9 by sunset. Windchill values across Cape Breton bottomed out at around -20. As the frigid wind whistled across the Gulf of St. Lawrence’s relatively warm waters, it picked up moisture and buoyancy, producing bands of snow squalls. Schools closed throughout the Island, power lines fell, and the Cabot Trail became impassable over North Mountain.
Perhaps the most remarkable thing about November 2018’s tempestuous weather is that it set few, if any, records. Vigorous storm systems and their attendant gales, abrupt temperature swings, and paralyzing snow squalls are not November rarities in Cape Breton, but their relentless regularity over the past month definitely was not normal. Perhaps we just experienced the future “normal” November as our climate continues to change.
Maximum wind gusts (in kilometres per hour) measured between November 10 and 16, 2018. Data from Cape Breton Mesonet.