美国有线新闻 CNN 美国加州久旱后遭严重暴风雨袭击（在线收听）

The U.S. state of California has been suffering a historic drought. Three years ago, its governor declared a drought state of emergency. Late last year, 97 percent of California was in drought. But today, the U.S. drought monitor says less than 60 percent of the state is under drought conditions.

What happened?

A series of winter storms all hitting in a short amount of time. Since Monday, more than seven inches of rain had fallen, mostly in northern California. 6 to 12 feet snow had fallen on the Sierra Nevada Mountains. They're California's biggest source for water storage and their snow could help refill nearby rivers and lakes, many of which have already risen considerably in recent days.

There's a major downside to this sudden soggy storms, though. Avalanches, flooding, river waters rising over their flood stages, soaking land, buildings and homes nearby. It's brought dangerous conditions to many Californians.

JENNIFER GRAY, AMS METEOROLOGIST: In the U.S., flash floods kill more people than tornadoes, hurricanes or lightning.

A flash flood creates a rush of moving water that can sweep a grown man off his feet, a car off the road, and even your entire home off its foundation.

When the ground become so saturated that water can no longer seep into the soil, it begins to run off quickly into rivers and streams and this causes a rise in water and a flash.

Densely populated areas have an extremely high risk of flash flooding, with the additional concrete and less grassy areas for the water to soak into the soil, and they can see flash flooding very quickly. In the mountainous terrain, the combination of gravity, plus the easy runoff can lead to catastrophic flooding, when all of that water is funneled into the rivers, creeks, and even the valleys.

Remember, flash flooding can happen in the blink of an eye, that's why it's so important to stay alert and pay attention in case a flash flood watch or warning is issued for your area.