Flooding persists on the other side of the country.This time, Indiana, where some areas were inundated by tremendous amounts of rain in just a couple of days.
Flooding persists on the other side of the country.
This time, Indiana, where some areas were inundated by tremendous amounts of rain in just a couple of days.
The culprit was a stalled boundary. When thunderstorms develop along a boundary that isn't moving much, they can:
move slowly
repeatedly develop over the same areas
Each storm can dump more rain onto the same locations, rapidly driving rainfall totals higher.
There was also a feed of tropical moisture—not a tropical cyclone, but deep, humid air flowing north from the Gulf. That moisture-loaded atmosphere gave these thunderstorms an enormous reservoir of water to wring out.
And that's been part of the flooding story across the eastern U.S. this summer: very warm, moisture-rich air combined with slow-moving or repeating thunderstorms. A warmer atmosphere can hold more water vapor, increasing the potential for exceptionally heavy downpours when all the other ingredients come together.
