In a previous post, I noted that there were some significant revisions to the 2006 and 2007 SPC historical tornado archive (the source of data for this site.) According to Gregorgy Carbin, the Warning Coordination Meteorologist at the SPC, the National Weather Service changed the way they reported latitude and longitude values in October of 2006. The person responsible for maintaining the SPC archive at the time inadvertently continued to convert the lat/lon values from minutes/seconds to decimal degrees, even though they were now being reported by the NWS in decimal degrees. This unnecessary conversion caused the lat/lon values to be slightly off. When this was discovered in late 2008, he corrected the lat/lon values, while also taking the opportunity to do some additional quality control.
As of last Saturday night (10/10/2009), these changes have been incorporated into the Tornado History Project database. Although not a comprehensive list, some key changes are listed below:
- The number of tornadoes for 2006 now stands at 1103 (up from 1101)
- The number of tornadoes for 2007 now stands at 1098 (up from 1093)
- 4 tornadoes were added for 2006 (20061230.22.42, 20061116.37.31, 20061229.48.115, 20061229.48.116), while 2 were deleted (20060311.5.7 and 20060311.29.17)*
- 11 tornadoes were added for 2007 (20070826.38.39, 20070914.37.1, 20070914.37.13, 20070920.27.19, 20070928.20.114, 20070928.20.115, 20070928.20.116, 20070928.20.117, 20070928.20.118, 20071019.26.24, 20071227.48.20), while 6 tornadoes were deleted (20070328.31.30, 20070504.20.41, 20070505.46.50, 20070505.46.59, 20070914.37.9, 20071018.26.19)*
* Index numbers are generated by the Tornado History Project to uniquely identify tornadoes within the site. The index number is not part of the official SPC data.