The first wave of the strongest storm of the winter began hitting Southern California on Wednesday, but the most damaging rains are expected Thursday.

The first storm in a two-part series has made its way to Southern California before the main storm begins Thursday, increasing the danger of flash flooding.

Flames burned through brush and vegetation, reducing the soil’s ability to absorb water — allowing water to possibly flow quickly, picking up debris and creating dangerous mudslides, debris flows and flash flooding.