Flash flood watch issued today for South Lake Tahoe

SOUTH LAKE TAHOE - Heavy rainfall and thunderstorms expected this afternoon could cause major mud and ash problems within the Angora fire site, areas below it and ultimately Lake Tahoe.

A flash flood watch for the Lake Tahoe Basin and particularly, South Lake Tahoe, has been issued by the National Weather Service for today. Forecasters anticipate isolated thunderstorms through much of the evening with relatively little wind associated with them that would usher them out expeditiously, said weather service meteorologist Jessica Kielhorn.

Rain is also expected Wednesday.

"The biggest concern would be the burn area of South Lake Tahoe. The steep terrain within the area is our main concern. As little as a third of an inch of rain could cause debris flows or flash floods," Kielhorn said.

Teams of researchers from the U.S. Forest Service, the Desert Research Institute and UC Davis surveyed the fire area this weekend and on Monday. There are three working scenarios of what could happen today and Wednesday if the fire area experiences a heavy amount of rain, said John Reuter, associate director of the Incline Village-based UC Davis Tahoe Environmental Research Center.

Less than an inch of rain in a downpour fashion could do three things, Reuter said. It could cause mud and ash to flow to the Upper Truckee River which flows directly to the lake. Or the debris flow could instead head into Washoe Meadow. The third scenario is the debris could build up and dislodge large rocks and dam itself in Angora Creek and when heavier amounts of precipitation hit, dislodge into the Upper Truckee.

All are serious and pose problems for Lake Tahoe and its famed clarity.