How new research led to North Dakota tornado's EF5 upgrade

A powerful tornado struck Enderlin, North Dakota, on June 20, causing significant damage and leading to a rare EF5 classification after new research. Here's what went into the new research that led to the upgraded classification.

Hurricane experts watch for rare 'Fujiwhara effect'

Mike Boylan, storm chaser and founder of Mike's Weather Page, joins LiveNOW's Andy Mac to discuss Tropical Storm Humberto and a tropical wave that could become Tropical Storm Imelda as they move through the Atlantic Ocean. If the two storms get too close to each other, it could trigger the 'Fujiwhara effect.'