New Delhi, July 27 -- A dangerous combination of extreme heat, severe thunderstorms, flash flooding and monsoon-driven rainfall is expected to affect much of the United States through July 29, according to the National Weather Service's (NWS) Weather Prediction Center (WPC).

While a powerful heat dome continues to bake the central and southern US, multiple storm systems are forecast to bring damaging winds, hail and flooding from the Upper Midwest to the Northeast. Meanwhile, the annual North American monsoon is triggering heavy downpours across the Southwest.

Here's what is happening and which places are most at risk.

The Weather Prediction Center says a broad upper-level high-pressure ridge, often called a "heat dome," is parked over...