Today is expected to be one of the chilliest days so far this winter, but meteorologists say Calgary will plunge even deeper into extreme cold this week.Temperatures are expected to drop as low as -37 C on Friday, per Environment Canada forecasts, before the cold snap starts lifting. The chill is so severe, it's threatening to break recent weather records. "We usually get cold snaps like this [in] January and February in Alberta, but this cold hasn't happened in about 20 years," said Environment