12:40 Update
Rain showers are tapering off in the Valley and Foothills, however, a few spotty showers still remain in the forecast. The Sierra is still picking up rainfall as of this update.
The threat of isolated thunderstorms for the Valley and Foothills will remain in the forecast until around 5pm this evening. The Sierra thunderstorm threat remains until 10pm tonight.
Any thunderstorms that develop have the potential to generate brief downpours, small hail and gusty winds.
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There are big weather changes today as the thunderstorm risk expands into the Valley for the morning and evening commute.
A weather system is moving in from the Pacific with the much cooler weather.
The highs on Friday will drop 5-10 degrees from yesterday.
Warmer and drier weather is ahead by Memorial Day with Valley highs in the 90s.
