A frozen Bryant Park fountain is one of everyone’s favorite “cold city” visuals. And it looked pretty epic on Thursday as the polar vortex blasted New York City with arctic air. The air was so cold that the National Weather Service warned of frostbite with as little as 30 minutes of exposure. Wind chill warnings and advisories cover virtually the entire region through mid-morning, and even by afternoon single-digit feels-like temperatures will be the norm. Click here for all severe weather alerts.