Storm increases risk of flash floods in Tuolumne County

As a storm brought rain to the valley Thursday, the threat of downpours and snow runoff increased the chances of flash flooding in the Sierra region.

Tuolumne County authorities urged motorists to use caution while traveling in the county. Power outages and lightning in Sonora were reported Thursday afternoon.

Officials are concerned about the overnight storm activity. Anyone who plans a visit to Yosemite National Park on Friday was advised to delay their arrival until after noon. The storm system was expected to bring heavy rain to the park, with the threat of water and debris on roadways.

Highways 120, 140 and 41 were open near Yosemite on Thursday evening but temporary road closures are possible for the safety of visitors, park officials said.

Modesto received a third of an inch of rain by 7 p.m. Thursday. The National Weather Service expected showers to continue Thursday night and showers with possible thunderstorms Friday before the storm activity tapers off Saturday.

This story was originally published February 9, 2017 at 7:59 PM with the headline "Storm increases risk of flash floods in Tuolumne County."