Multi-day storm is threatening flooding and mudslides in Southern California: What to expect and when

CNN A strong Pacific storm is bringing soaking rain to Southern California and raising the liability of life-threatening flooding mudslides and debris flows especially near burn scars in the Los Angeles area A mix of heavy rain and strong winds moved through northern and central California on Thursday Widespread rainfall totals of to inches were observed along the coast into Friday morning with isolated amounts of to inches in the coastal mountain ranges San Francisco received nearly an inch and a half of rain Thursday almost of November s average November marks a transition into the rainier winter season with December to February marking the wettest months of the year in the Bay Area Winds in the higher elevations gusted to mph Thursday with San Francisco gusts topping mph The winds started to ease as the system dropped into Southern California early Friday but the flood threat is intensifying as an atmospheric river feeds moisture from the ocean into the storm Parts of the region including much of the Los Angeles area are under a Level of liability of flooding rainfall on both Friday and Saturday according to the Weather Prediction Center An initial wave of heavy rain for southern California caused flooding and a mudslide late Thursday night on portions of Highway in southern Santa Barbara County according to the National Weather Utility This round of rain is expected to ease by Friday afternoon A second more intense wave will move into the region Friday night into Saturday with prolonged heavy rain manageable Rainfall rates could be as high as an inch per hour at times This second round of rain will also have the added danger of falling over already-wet ground which struggles to absorb additional rain and will start flooding quicker than dry ground There s also the foreseen for isolated severe thunderstorms embedded within the heavier rain Friday night into Saturday Specific of these storms could produce damaging wind gusts hail and perhaps a short-lived tornado Much of the Los Angeles area is under a flood watch through p m Saturday The National Weather Function warns that the storm could trigger life-threatening debris flows knock out power and flood roads Burn scar areas on alert Burn scar areas from new wildfires in the region will be particularly vulnerable to mudslides and debris flows Not only do wildfires destroy vegetation that would normally soak up selected of the rainfall but their extreme heat can alter the soil creating a water-repellent layer just below the surface Officers have warned residents near the up-to-date Palisades Hurst and Sunset fires burn scars to be prepared to evacuate Residents especially those in vulnerable areas should start taking precautions at once to prepare for the storm and protect their interests the National Weather Function in Los Angeles noted This scenario would potentially create a great number of notable impacts area-wide including workable debris flows in the burn areas critical ponding of roads and highways mudslides through the canyons fallen trees etc Residents can pick up sandbags at Fire Stations throughout the City with sand also available for free at select locations The heaviest rain should ease late Saturday but the region isn t in the clear right away Showers linger into Sunday and the ground will be saturated It won t take much rain to trigger more minor flooding or keep roads slick especially in spots that usually drain slowly after big storms