Despite having had a relatively mild winter so far, Canada could be hit with a polar vortex—which brings with it cold air and frigid temperatures—as soon as next week, Environment Canada warns. A polar vortex is a low pressure system that spins and locks cold air near the North pole constrained by a strong polar jet stream. But when it weakens, the cold air will spill out from the Arctic and move southward, ushering the coldest air into Canada.  “And now we see that it’s weakened and weakened [and that] is not good,” David Phillips, senior climatologist at Environment Canada told CBC News. Manitoba all the way to the Atlantic Coast provinces are likely to experience significant temperature drops next week, with overnight lows ranging from -15 C to -20 C, and daily highs several degrees below freezing, Phillips told CTV News. And, the polar vortex could drop the overnight temperatures in …