Key Takeaways
- A major storm is expected to bring months’ worth of rain and powerful winds to Southern California, with a high risk of flooding and debris flows.
- The storm is expected to affect nearly 6 million people in Los Angeles, San Bernardino, Ventura, and Santa Barbara counties.
- Evacuation orders and warnings have been issued for areas in and around burn scars, including the Eaton and Palisades fire zones.
- Strong winds and heavy snow are also expected, with sustained winds of 30-50 mph and gusts up to 80 mph in the mountains.
- The storm is part of a larger pattern of atmospheric river-fueled storms that will continue through the week, with another storm expected on Thursday and Friday.
Introduction to the Storm
A powerful storm is gearing up to hit Southern California, bringing with it months’ worth of rain and powerful winds. This storm is the latest in a series of atmospheric river-fueled storms that have been aiming for the region, and it is expected to be the most potent of the bunch. The storm is coming on the heels of a previous storm that killed at least one person and brought intense flooding to Northern California over the weekend. The new storm was forming over the Pacific Ocean early Tuesday morning and is expected to start affecting the California coast from north to south with rain and wind late Tuesday evening.
Storm Timeline and Expected Impacts
Torrential rain is expected to start in Southern California early Wednesday morning and continue through the evening. A Level 4 of 4 "high" risk of flooding rain has been issued for the region, which includes nearly 6 million people in portions of Los Angeles, San Bernardino, Ventura, and Santa Barbara counties. This level of risk is significant, as high risks are issued on fewer than 4% of days per year on average, but are responsible for more than 80% of all flood-related damage and 36% of all flood-related deaths. The National Weather Service in Los Angeles has warned of widespread and significant urban flooding, rock/mudslides, and debris flows, which are not just confined to burned areas.
Flooding and Debris Flow Risks
The risk of flooding and debris flows is particularly high in areas that have been affected by recent wildfires, including the Eaton and Palisades fire zones. The scorched ground in these areas repels water instead of absorbing it, quickly turning rain into a surge of floodwater that pulls mud and debris with it. Life-threatening debris flows are possible on recent burn scars, and evacuation orders and warnings have been issued for areas in and around these zones. Los Angeles County has announced evacuation orders and warnings for 383 properties, and Ventura County has issued evacuation warnings for parts of the county. Santa Barbara County is also under evacuation warnings, including some areas within the Lake Fire burn scar.
Government Response and Preparations
California Governor Gavin Newsom has mobilized state resources ahead of the holiday week storm, with agencies pre-positioning crews and equipment. The governor’s press office has announced that the state is taking steps to prepare for the storm, including deploying emergency personnel and equipment to affected areas. The National Weather Service has also issued warnings and advisories for the region, including a high wind warning for the mountains and a flood watch for the coastal and valley areas.
Additional Storm Impacts and Timing
In addition to the flooding and debris flow risks, strong winds are also expected to add to the danger. Winds will be most ferocious in the region’s mountains, where sustained winds from the south of 30 to 50 mph are possible with gusts to 80 mph. The holiday danger doesn’t end there, as another atmospheric river-fueled storm is expected to follow on Thursday and continue into Friday. All told, rainfall totals in Southern California through the end of the week could be as much as 4 to 8 inches in coastal and valley locations, while foothills and mountains see 8 to 12 inches. To put those totals into perspective, a city like Los Angeles could see anywhere from two months’ worth of rain to nearly half a year’s worth in just a week.
Long-Term Impacts and Relief
The same abundant moisture that is set to slam Southern California will also fuel feet of snow farther north in the Sierra Nevada, making travel there difficult or impossible at times. The heavy snow will be a big change for the region, which has had much less snow than usual to start the season. Some relief from this nonstop stormy pattern looks to finally arrive for the upcoming weekend, but until then, residents and travelers should exercise extreme caution and follow evacuation orders and warnings. The National Weather Service and local authorities will continue to monitor the situation and provide updates as necessary.
