Sometimes, after a large thunderstorm complex has passed, an area of very cool air can drop down from the mid-levels of the atmosphere. In certain, hard to predict circumstances, this can produce a small-scale high-pressure/low-pressure situation called a wake low that can cause very strong winds to blow for an hour or two.
Wake low winds are usually found in a region of cloudy, cool air. The air temperature is usually in the 60s. They often blow at around 20-40 mph but can be as strong as 50-80 mph and are capable of doing considerable damage. However, they happen after the passage of thunderstorms and often leave people rather confused. These wake low winds happen almost every summer somewhere over the Dakotas and Minnesota but are relatively rare for any one location.