A cold front will team up with warm, humid air as it tracks eastward, setting the stage for intense storms to spread from the Plains on Tuesday to the East Coast by Thursday.

It was only a matter of time before a long-lived heat wave would develop in the Midwest and Northeast. This one could last from late this week into early next week.

Storm chasers captured spellbinding video of a large tornado that stayed on the ground for nearly an hour near Dickens and North Platte, Nebraska, on Monday evening. Watch how the twister seemed to shape-shift as it tore across wide open landscapes.

Outdoor activities in some parts of the country might require a plan to shelter from lightning and/or take heat precautions.

While the heat and humidity of summer have already arrived for some, the new season's arrival officially comes with the solstice Friday evening. Here's a look at how the forecast is shaping up for July through September.