What are county-segments in NCDC tornado data?
A county-segment is that portion of a tornado’s path within a single county. If a tornado stays in one county, then a “tornado” is the same as a “segment.” But this also means that tornadoes are counted twice when they cross into another county, three times when they enter a third county, and so forth. The reason for county-segment tornado recordkeeping is that the National Weather Service verifies tornado warnings by county. So when you look at NCDC tornado databases or the NWS Natural Hazard Statistics (based on Storm Data), you are not counting tornadoes, but instead county-segments of tornado tracks. This causes inflation of the tornado totals often reported by media and others who do not notice this important distinction.
A county-segment is that portion of a tornado’s path within a single county. If a tornado stays in one county, then a “tornado” is the same as a “segment.” But this also means that tornadoes are counted twice when they cross into another county, three times when they enter a third county, and so forth. The reason for county-segment tornado recordkeeping is that the National Weather Service verifies tornado warnings by county. So when you look at NCDC tornado databases or the NWS Natural Hazard Statistics (based on Storm Data), you are not counting tornadoes, but instead county-segments of tornado tracks. This causes inflation of the tornado totals often reported by media and others who do not notice this important distinction.
