RIVERSIDE (CBS) — Scattered showers and thunderstorms are expected in Riverside County Tuesday, prompting a flash flood watch for the mountains.

According to the National Weather Service, an upper level disturbance off the coast of Southern California will bring showers and thunderstorms to the region.

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“These thunderstorms have the potential to produce, hail, frequent lightning, locally heavy rainfall and gusty winds,” according to an NWS advisory. “When you hear thunder, move inside immediately.”

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The Weather Service issued a flash flood watch for the mountains until 9:00 p.m.

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Temperatures around the county are expected to peak in the low 90s in the Inland Empire and mid-80s in the mountains.