There’s no vem­ber like Novem­ber

Cape Bre­ton Weather

The Victoria Standard - - Weather - BILL DANIEL­SON

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.

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