The above radar image was taken from the Yuma, AZ radar just a few moments ago. A Severe Thunderstorm Warning was recently issued for portions of Imperial County, California (noted by the red warning box on the image above).
Today is one of those relatively rare days in southern California where several parameters are in place for strong to severe storms. Low-level moisture is relatively high for the area, as noted by the 60 degree dewpoints outlined by the green contours on the image above.
As is typical for the region, lightning content of this activity will be very high (see same radar image as above with lightning overlaid in the next image below):