8:45 p.m. UPDATE: The National Weather Service has extended its urban and small-stream flood advisory for San Luis Obispo County through 10:45 p.m. Sunday.
It had originally been set to expire at 8:45 p.m.
As of 8:30 p.m., moderate-to-heavy rain had pushed into the eastern and southern portions of the county, according to the Weather Service.
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The National Weather Service has issued an urban and small-stream flood advisory for San Luis Obispo County, including San Luis Obispo and Paso Robles, through 8:45 p.m. tonight.
Dopper radar at Vandenberg Air Force Base near Lompoc has shown that moderate to heavy rain has dampened the western half of San Luis Obispo County, and will overspread the area by 5:30 p.m., according to the Weather Service.
There is a slight chance of thunderstorms, and rainfall rates are expected to average a quarter of an inch to a half an inch per hour in coastal and valley areas, and up to three quarters of an inch per hour in the foothills and mountains.
The heavy amount of rain in such a short period is expected to cause ponding of water on roads through this evening, with flooding possible in low-lying areas, intersections and underpasses.
The Weather Service warns drivers to avoid areas where water covers the roadway because water depths might be too great to allow vehicles to pass through safely.