Exceptionally severe winter storms that overwhelm local government result in major disaster declarations. Each National Weather Service forecast office in the United States reports winter events for a specific group of counties, known as the county warning area. Such events are reported as blizzard, ice storm, winter storm, heavy snow, or winter weather. They are archived by the National Climatic Data Center and are published in Storm Data, a monthly periodical. Using Storm Data, all winter reports in Oklahoma from 1 November 1999 to 1 May 2010 were compiled into a database. The results of this study demonstrated that while counties in northern Oklahoma received the highest number of winter reports, when compared with climatology winter storm, heavy snow, ice storm, and blizzard storm types yielded an above-average occurrence across much of southwest and central Oklahoma over the study period.
Disaster information, obtained from the Federal Emergency Management Agency, showed that from 1 November 1999 to 1 May 2010 Oklahoma led the nation with nine winter-related federal disasters, resulting in nearly $800 million (U.S. dollars) in federal aid. High-impact events, determined by disaster declarations, were most frequent across southwest, central, and northeast Oklahoma, and southwest Oklahoma experienced a disaster nearly every third winter event. Over much of Oklahoma, ice storms were more likely to result in a disaster than winter storm, blizzard, and heavy snow events combined. Spatial distributions of federal aid showed that rural counties were most impacted by the winter weather disasters and required greater federal assistance.