By Dave Toplikar

Wed, Aug 6, 2008 (8:47 p.m.)

Thunderstorms were firing up northeast of Las Vegas this evening, bringing the chance of flash flooding.

The National Weather Service has issue a flash flood warning for North Central Clark County until 10 p.m.

The weather service reported that at 8:20 p.m., the weather service's Doppler radar indicted very heavy rain from a thunderstorm just south of Moapa, with the heaviest rain falling in the California Wash and surrounding areas.

The weather service said excessive runoff from the heavy rainfall is expected to cause flooding of washes, drainage areas, highways, streets and low water crossings.

"When you approach flood waters ... Turn around ... Don't drown," the weather service wrote in its advisory statement.

The Las Vegas area can expect a 20 percent chance of showers and thunderstorms before 11 p.m., the weather service said. Tonight's low will drop to 84 degrees.

Thursday's forecast calls for isolated showers and thuderstorms after 11 a.m., with mostly sunny skies and a high near 104. The chance for precipitation is 20 percent Thursday, forecasters say.