Canada's Top Ten Weather Stories for 2012
10. Historic Ice-jam Flooding on the Saint John River
The first days of spring were marked by a mandatory evacuation for 500 residents of Perth-Andover and Tobique First Nation when the Saint John River and several of its tributaries spilled onto nearby fields and roads. With damage to government buildings, the area hospital, two schools, a town hall and the fire station exceeding $25 million, officials declared a local state of emergency. Two days later, flood waters receded on the village’s main street leaving truck-sized chunks of ice. Some lodged in trees as a reminder of how high the water levels had climbed. Beleaguered homeowners and small businesses faced a messy and muddy cleanup made worse by unseasonably cold temperatures that created another disaster – unheated buildings with frozen water pipes.
Perth-Andover has endured five major floods in 25 years. This time, water levels reached at least a metre higher than in any previous flood due to unprecedented March warmth. The higher temperatures fast-tracked an unusually early spring thaw and rapid snowmelt in the upper reaches of the Saint John River in New Brunswick, Quebec and Maine. Just days before the flood, St. Leonard, New Brunswick experienced record warmth above 20°C over three days that assaulted the winter’s snowpack from a depth of 60 cm to 7 cm in less than a week. When temperatures zoomed 15 degrees above normal with melting around the clock, nervous residents watched the spring freshet come fast and furious. This included the first ice jam that started up about a kilometre northwest of Perth-Andover at the confluence of the Saint John, Aroostook and Tobique rivers on March 20 and 21. Still, the flood could have been worse if the seasonal snowpack upstream had been more plentiful; the ground frost deeper, which would have allowed less water to percolate instead of running overland; or if there had been a significant spring soaker.
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