Record Warmth Fuels Midwest Tornado Outbreak 
Record winter warmth created the perfect storm for deadly Midwest tornadoes, experts say.
ScienceExplained
Record Warmth Fuels Midwest Tornado Outbreak
US Chills as World Warms: Climate Paradox Explained 
Scientists explain the climate paradox behind the US deep freeze and global heatwaves. How rising temperatures are reshaping extreme weather.