加利福尼亚州官员和气象预报员敦促假日出行者避开道路，并重新考虑圣诞旅行计划，因为一系列强力的冬季风暴带来了持续的降雨、强风和高山积雪。
美国国家气象局警告称，风暴于周二深夜开始移动，并预计在圣诞节前夕加剧。当局表示，由于多条大气河流预计将席卷该州，数百万计划跨州出行的人们很可能会面临极其危险、甚至可能无法通行的路况。
“如果你计划在圣诞节假期期间出行，请重新考虑你的计划，”美国国家气象局洛杉矶分局气象学家阿里尔·科恩在周二的一场新闻发布会上说道。
气象预报员表示，南加州可能迎来多年最潮湿的圣诞节，并警告去年一月野火烧过的地区可能出现山洪、泥石流和碎屑流。洛杉矶县官员称，他们正在挨家挨户通知约380户高危居民撤离。
萨克拉门托河谷和旧金山湾区大部分地区周五前持续处于洪水监测和强风警报状态。气象部门预警称，内华达山脉部分地区周三将出现强降雪和阵风，导致“近乎白茫”的天气状况，山区隘口的通行将“几乎无法实现”。
北部沿海地区还可能遭遇强雷暴天气，并存在较小的龙卷风风险。
当地官员表示，北加州地区因暴雨和山洪已引发多起水上救援事件，并造成至少一人死亡。沙斯塔县警长迈克尔·L·约翰逊于周一宣布进入紧急状态，以应对持续强降雨，同时便于州政府协助开展减灾及搜救行动。
美国国家气象局气象学家迈克·沃福德表示，南加州往年同期降雨量通常为0.5至1英寸（1.3至2.5厘米），但本周许多地区的降雨量可能达到4至8英寸（10至20厘米）。山区降水量可能更大。中部海岸部分地区阵风风速或将达到每小时60至80英里（96.5至127.8公里）。
官方预计，暴风雨期间将出现多处道路封闭和机场延误情况，树木倒塌和电线断裂也可能发生。本周洛杉矶部分地区已发布疏散警告。
该县在火灾烧灼区域周围设置了K型护栏（一种路障），以在暴雨期间拦截滑落的碎石。代表阿尔塔迪纳地区的洛杉矶县督察凯瑟琳·巴杰表示，居民还可领取免费沙袋用以保护住宅。
洛杉矶警察局局长吉姆·麦克唐奈表示，许多身处山火烧毁区域的人在接到疏散通知后决定不撤离。他敦促这些人重新考虑这一决定。
他表示：“这场风暴带来的威胁真实存在且迫在眉睫。”
地方和州政府官员正加紧准备应对本周可能发生的紧急情况。州政府已向沿海及南加州多个县部署了应急资源和救援人员。加州国民警卫队也随时待命提供支援。
大气河流是形成于海洋上空、流经天空的狭长水汽带，它将水分从热带地区输送至北纬地区。
美联社记者索菲·奥斯汀（加利福尼亚州萨克拉门托）和杰茜卡·希尔（内华达州拉斯维加斯）对本报道亦有贡献。
California officials and weather forecasters urged holiday travelers to avoid the roads and reconsider Christmas travel as a series of powerful winter storms brought relentless rains, heavy winds and mountain snow.
Storms began to move in late Tuesday evening and were expected to intensify into Christmas Eve. Authorities said the millions of people expected to travel across the state will likely meet hazardous, if not impossible, conditions as several atmospheric rivers were forecast to make their way through the state, the National Weather Service warned.
If youre planning to be on the roads for the Christmas holidays, please reconsider your plans, said Ariel Cohen, a National Weather Service meteorologist in Los Angeles, during a Tuesday news conference.
Forecasters said Southern California could see its wettest Christmas in years and warned about flash flooding, mudslides and debris flows in areas scorched by last Januarys wildfires . Los Angeles County officials said they were knocking on the doors of some 380 particularly vulnerable households to order them to leave.
Much of the Sacramento Valley and the San Francisco Bay Area were under a flood watch and a high wind warning through Friday. Forecasters warned heavy snow and gusts were expected to create near white-out conditions Wednesday in parts of the Sierra Nevada and make it nearly impossible to travel through the mountain passes.
Theres also a risk of severe thunderstorms and a small chance of tornadoes along the northern coast.
Heavy rain and flash flooding already led to water rescues and at least one death in Northern California, local officials said. Shasta County Sheriff Michael L. Johnson on Monday declared a state of emergency to prepare for more rain and allow the state to help with hazard mitigation and search and rescue operations.
Southern California typically gets half an inch to 1 inch (1.3 to 2.5 centimeters) of rain this time of year, but this week many areas could see between 4 and 8 inches (10 to 20 centimeters), National Weather Service meteorologist Mike Wofford said. It could be even more in the mountains. Gusts could reach 60 to 80 mph (96.5 to 127.8 kph) in parts of the central coast.
Officials expect multiple road closures and airport delays during the storms. Downed trees and power lines are also possible. Parts of Los Angeles are under evacuation warnings this week.
The county put up K-rails, a type of barrier, around the burn scar to help catch sliding debris during rainstorms. Residents could also pick up free sandbags to protect their homes, said Kathryn Barger, a Los Angeles County supervisor representing Altadena.
Many people in burn scar areas decided not to leave after receiving the evacuation notification, Los Angeles Police Department Chief Jim McDonnell said. He urged them to reconsider.
The threat posed by this storm is real and imminent, he said.
Local and state officials are gearing up to respond to emergencies through the week. The state has deployed resources and first responders to a number of counties along the coast and in Southern California. The California National Guard is also on standby to assist.
An atmospheric river is a long, narrow band of water vapor that forms over an ocean and flows through the sky, transporting moisture from the tropics to northern latitudes.
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Associated Press writers Sophie Austin in Sacramento, California, and Jessica Hill in Las Vegas contributed to this report.
