All locations will be closed Dec 15, 22-25, 29 and Jan 1 and close early during the last 2 weeks of December. See December Calendar for details.
The Storm Prediction Center of the National Weather Service includes maps, tracks, averages and summaries that apply to tornadic activity in the United States. The Norman office of the National Weather Service keeps a historic list of tornado data by county. The EF Scale became operational on February 1, 2007 and is used to assign a tornado a 'rating' based on estimated wind speeds and related damage.
Source: National Weather Service web sites.