The severe weather outbreak predicted by NOAA for March 2 is partially due to a dip in the jet stream, bringing cold air from Canada to mix with warm, moist air from the Gulf of Mexico. Where these two differing air masses meet is often an area of severe weather, hail, winds, and even tornadoes. The position of the jet stream can be clearly seen in this image of wind speed at 500 millibars (18,000 feet) in the atmosphere, taken from output from the NOAA North American Model for March 2, 2012 at 7pm EST.