I will make this a short one because that is all that needs to be said.  Yesterday there were mid/upper-level clouds that hampered instability in many areas except the Kern County zones, where thunderstorms did happen south and north of Bakersfield.  Today, clearer skies mean more instability in the risk zones so this should be a more active day.  On top of that, the focus spot is the Inland Empire zones, surrounding Perris to Riverside with Moreno Valley between so let me just call it a risk for the entire Inland Empire areas along the Elsinore Convergence Zone and westward a bit as well.  This risk will only be today.

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SOUTHERN CALIFORNIA WEATHER FORCE MAIN:

All other mountain/desert areas, you are in the risk as well.  The weakest of this risk however will be some of the high desert locations around Barstow and the Kern Desert zones, where Barstow will have the better chance of storms on Monday due to the El Mirage Convergence Zone southwest of you activating.

Overnight into Monday morning, the risk turns severe to Needles, California, along I-40 and also storms moving through Las Vegas Monday morning as well.

ELSINORE CONVERGENCE ZONE:  This convergence zone runs from Lake Elsinore northeast to Banning.  You can consider it like a fault-line in weather where storms focus more on, as do quakes along a fault.  Storms in this zone tend to affect Perris/Moreno Valley and even Riverside at times.  Today is the better chance, likely the last chance this season the zone can go off.

That is all.  After today it will be a southwest flow for the final day of storms in this session across the forecast area, so only mountain/desert areas will be affected.