Flash flooding, hail and tornadoes? Warnings issued as sudden storm hits SLO County

The National Weather Service warned of flash flooding, hail and even a small tornado for inland San Luis Obispo County as a freak storm swept through the region on Thursday.

Thunderstorms building above San Luis Obispo County could unleash heavy rainfall near the eastern border during the afternoon and evening — leaving inland areas vulnerable to flash flooding, the Weather Service said Thursday afternoon.

As a result, it issued a flash flood warning for southeastern San Luis Obispo County and a flood advisory for interior San Luis Obispo County through 7 p.m.

The warning said Doppler radar indicated thunderstorms were producing heavy rain across the warned area, with between 1 and 3 inches of rain already falling.

The expected rainfall rate was 1 to 2 inches in an hour, the agency said, noting flash flooding was ongoing or expected to begin shortly and landslides were expected.

The Weather Service also extended an existing flood watch for the county until 5 a.m. on Friday and warned people to stay off of mountain roads.

"Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations," the Weather Service said in the flood watch.

"Not all areas will get rain, but in the most favorable areas, rainfall rates up to an inch per hour are possible with hail and gusty winds as well," the Weather Service said.

The thunderstorm even creates the potential for a funnel cloud or small tornado, the agency said.

The Weather Service also warned of hail and gusts of wind that reach 40 mph from 3:42 to 4:15 p.m. on Thursday.

The storm should will blow east of Ventura County by Friday afternoon, ushering in a dry and sunny weekend for San Luis Obispo County.