An Investigation of an Anchorage Rotor Event

On February 1, 2012 a mountain wave across the Chugach Mountains initiated rotors across the city of Anchorage. Radar indicates the presence of strong wind shear across the Anchorage Bowl, and strong erratic wind gusts were observed by National Weather Service forecasters across town. Heavy snow also occurred during the event, which, combined with strong winds resulted in blowing and drifting snow. As a result, some mountain roads became impassible. While models indicate the presence of a strong mountain wave throughout the entire event, it appears that the initiation of rotors is tied to upper level dynamics.