Parts of Southern California were under a rare “high risk” of excessive rainfall on Sunday and Monday, and it’s important to take such a threat seriously because this magnitude of flooding can have destructive impacts.
NOAA’s Weather Prediction Center (WPC) is the agency responsible for issuing daily excessive rainfall outlooks. The outlooks use four categories – marginal, slight, moderate and high – to indicate the probability of excessive rainfall leading to rapid-onset flooding within 25 miles of a point.
When a high risk – the highest risk level that can be issued – is in place, it means severe, widespread flash floods are expected in the highlighted areas.