Dry and gusty Santa Ana winds sweeping through Southern California are predicted to bring days of critical fire weather conditions. Red Flag warnings by the National Weather Service began late Sunday and will last through Thursday. Meteorologists say relative humidity levels will plunge into the single digits and teens. Officials have dedicated extra resources to fire-prone areas. Forecasters say it could be the strongest and longest Santa Ana wind event so far this season, with gusts capable of bringing down tree branches and power lines.