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Canada's Top Ten Weather Stories for 2011
Quebec - Regional Highlights
One Wet March
Québec City set a new record rain and snow total for March at 172.9 mm, owing to the passage of four major low-pressure systems during the month. It was the third-snowiest March on record at 109.3 cm, while in the rain plus snow department there were seven days with heavy precipitation amounts (10 mm or more); the norm is between one and two days. Sherbrooke had its second-snowiest March on record with 87.9 cm (normal is 49.1 cm). And from March 12 to 13, several regions recorded large quantities of rain, triggering some local flooding along swollen rivers.
April Showers Bring Spring Flooding
A prevailing weather pattern over Estrie and Montérégie was unprecedented in April, with regards to the duration, frequency and quantity of heavy precipitation. Combined with snowmelt, the excessive snow and rain triggered historic flooding. Only two Aprils in the last century had as much precipitation (1974 and 1996). Sept-Îles, with 89.3 cm of snow (normal is 37.5 cm), registered its snowiest April on record with records dating back to 1944, bucking a pattern of lower snowfalls seen over the past decade.
An Active Summer Storm Season
Summer in Quebec featured an unusually high number of days with thunderstorms, many severe. It was the third-stormiest summer in 55 years, featuring 21 days with thunderstorms compared to an average of 13. Montréal had its seventh-stormiest summer with 21 days of thunderstorms, compared to an average of 15. Five tornadoes were reported, which is near the provincial normal of six, with the biggest touching down in Sainte-Elisabeth-de-Proulx, north of Lac Saint-Jean. The tornado knocked out power to about 500 people during a three-day bout of violent weather between August 5 and 7. Another 1,600 people in Lac Saint-Jean were left in the dark by thunderstorms that rolled along a cold front. On the same day, a microburst ploughed through Saint-Ludger-de-Milot. The violent wind events over three days uprooted or broke thousands of trees, damaged houses and properties, and created blackouts.
The summer in Quebec was record-breaking for rainfall. Normal summer rain totals for the province range between 250 and 300 mm, but in 2011 the total exceeded 450 mm. North of Québec City, the Beauce, the inner Gaspé Peninsula, the Mauricie region and Lac-Saint-Jean were impacted most, receiving close to 550 mm. Roberval and Bagotville registered their wettest summer and wettest August on record and, for Roberval, August’s 291 mm of rain made it the city’s wettest month ever. After a rainy spring and summer, water levels on a number of rivers in Estrie, Montérégie and Beauce were well above normal for much of the year. And in Montréal, it was also the wettest August on record, with 224.8 mm or 143 per cent more rainfall than normal – beating the previous wettest ever at 169.6 mm in 1982. The city had 18 wet days in August, with five days above 20 mm [normal is 1.3]. Days at or above 25 mm numbered four, with never more than three in any previous month. Over the six months of spring and summer, Montréal experienced its wettest half year ever, with 785 mm of precipitation [normal is 495 mm]; the previous record was 710.6 mm in 2006.
On September 13, three squall lines preceding the passage of a strong cold front swept through southern Quebec in a southeasterly direction. Regions around Montréal, in Montérégie, the lower Laurentians, the Eastern Townships, and Beauce experienced torrential rainfalls up to 50 mm in less than two hours. Accompanying the heavy rains were strong gusty winds, frequent lightning and, in some places, cherry-sized hail. Microbursts generating winds between 100 and 120 km/h hit Saint-Colomban (Lower Laurentians) and Saint-Prosper (Beauce). Powerful winds brought down thousands of trees on vehicles, houses and hydro lines.
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