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SAN DIEGO (CNS) – The National Weather Service issued a flash flood watch Sunday from noon to 7 p.m. for the San Diego County mountains.

Monsoonal moisture and daytime heat was predicted to increase the potential for strong thunderstorm development over the mountains Sunday afternoon, the NWS said.

A weak inverted trough brought widespread showers and a few thunderstorms overnight across the region. That trough moved on to the northwest and carried most of the showers with it, forecasters said.

Most of the rain fell in a swath from the northern Coachella Valley, southwest across Riverside and into northwest San Diego County.

High temperatures along the coast Sunday were predicted to be 75-79 degrees with overnight lows of 64-71. Highs in the western valleys will be 84- 89 and near the foothills, 90-95, with overnight lows of 64-70.

Mountain highs were expected to be 87-94 with overnight lows of 64-72. Highs in the deserts will be 105-110 with overnight lows of 82-87.

Thunderstorms were expected over the mountains again Monday, decreasing into midweek, before increasing again later in the week as a monsoonal flow prevails around strong high pressure over the Rocky Mountains.

Mild nights and seasonally warm to hot days were expected all week, along with higher humidity.

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