Dry thunderstorms moving through the Bay Area from Thursday afternoon through this morning (Aug. 7), led the National Weather Service to issue a "Red Flag Warning" for the period from 2 p.m. Thursday through 11 a.m. Friday. The warning prompted the closure of some Bay Area parkland as a precaution.

The chance of thunderstorms was expected to diminish by late Friday morning, according to forecasters. Weather service officials said they expected associated lightning strikes to be the most frequent in Monterey and San Benito counties initially, then spread north.

The thunderstorms were expected to produce little or no rain and consequently increase the risk of wildfires.

The high fire danger in the Bay Area has prompted the San Francisco Public Utilities Commission to close 23,000 acres of wildland on the Peninsula.

The Peninsula Watershed – which comprises the land around the Crystal Springs Reservoir, Pilarcitos Lake and San Andreas Lake – was closed at noon Thursday and will remain closed Friday, according to the SFPUC.

The reservoirs help provide drinking water to 2.6 million SFPUC customers in San Francisco, Alameda, Santa Clara and San Mateo counties and the land around them has popular trails for hiking, running and biking.

All trails in the area are closed through Friday and the SFPUC is limiting its own activities in the area as well. In addition the SFPUC is closely monitoring the 36,000-acre Alameda Watershed in the East Bay.

Massive wildfires have consumed thousands of acres of drought-ridden land in California in recent weeks, including nearly 70,000 acres in Lake, Yolo and Colusa counties and 8,000 acres in Napa and Solano counties.