Capping a week that began with scorching heat and saw high humidity with nighttime lightning shows, the National Weather Service issued a flash-flood watch through Sunday night for the mountains of northern Santa Barbara County.

A stalled upper-level low-pressure system off northern Baja has been pushing subtropical moisture into Southern California from Mexico, causing scattered thunderstorms, gusty winds and possible hail at higher elevations. Scattered showers in coastal areas are possible.

Saturday afternoon, the weather service said a cluster of strong thunderstorms was moving through the Cuyama Valley into San Luis Obispo County. Hail up to a half-inch in diameter was expected, along with heavy rain and dangerous lightning. Flooding of low-lying areas and minor debris flows near the La Brea Fire burn area were possible.

In the Ventura County backcountry earlier Saturday, heavy rain and mudslides forced the closure of Highway 33 and Lockwood Valley Road near Frazier Park, according to the California Highway Patrol. No injuries were reported.

There is a 20 percent chance or rain and thundershowers overnight Saturday with temperatures in the mid-60s to low 70s on Sunday and Monday.

Noozhawk publisher Bill Macfadyen can be reached at wmacfadyen@noozhawk.com. Follow Noozhawk on Twitter: @noozhawk.

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William M. Macfadyen, Noozhawk Publisher

Bill Macfadyen is Noozhawk’s founder and publisher. Contact him at wmacfadyen@noozhawk.com, and follow him on Instagram: @bill.macfadyen. The opinions expressed are his own.