Service Outage Alert: Beginning at 8:30 p.m. on Sunday, Feb. 26, all web services requiring your library card to log in will be unavailable for approximately 1 hour during routine maintenance. More information.
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.