Map Porn: Average Date of Year's First Tornado Warning

This map shows the average date that each National Weather Service forecast office issues its first tornado warning every year, based on data from 1986-2013. It's pretty illustrative of how tornado climatology tends to work in the United States. The Deep South sees its first round of severe weather during the winter,… » 4/03/14 3:54pm 4/03/14 3:54pm