Santa Barbara County authorities ordered mandatory evacuations Monday for residents below fire-ravaged mountains ahead of a “fast-approaching” storm that could cause flooding and mudflows. “Those hills are filled with silt, with rocks, with boulders, there’s plenty more up there that could come down,” Sheriff Bill Brown told reporters Monday, adding that conditions may be more precarious than in January, before deadly mudslides swept through Montecito. “Don’t be fooled into thinking that this can’t happen again.”