Since August 11, severe storms have battered the Chicago area, Indiana and the northeastern United States, killing at least seven people in Indiana.
Indiana is seeking federal emergency aid, while power has returned to 99% of affected northwest Indiana customers.
Pulse measures how actively a story is being covered right now.
Every article counts as a vote whose weight fades over time — an article published today counts as 1.0, one from two days ago counts 0.5, four days ago 0.25, and so on (a 2-day half-life). Pulse is the sum of those weights, so fresh coverage lifts it and old bursts fade away smoothly.