All this severe winter weather has the Homeland Advisory Group staff talking again about the ARkStorm. Beginning on Christmas Eve, 1861, and continuing into early 1862, an extreme series of storms lasting 45 days struck California. The storms caused severe flooding, turning the Sacramento Valley into an inland sea. The storms were caused by atmospheric rivers, a hurricane-like phenomenon that occurs on the west coast. A storm comparable to that of 1861-1862 could occur again. To prepare for a storm of this magnitude and greater, a team of atmospheric scientists, U.S. Federal and State agencies and academic institutions have created a model scenario, called ARkStorm, for understanding the damage and impacts from a California winter stormThe USGS and US Department of the Interior released an alarming study identifying this new serious risk to California. The hypothetical storm would strike the U.S. West Coast and be similar to the intense California winter storms of 1861 and 1862 that left the central valley of California impassible. The storm is estimated to produce precipitation that in many places exceeds levels only experienced on average once every 500 to 1,000 years.
In the ARkStorm scenario, flooding overwhelms the state’s flood-protection system, which is typically designed to resist 100- to 200-year runoffs. The Central Valley experiences hypothetical flooding 300 miles long and 20 or more miles wide. Serious flooding also occurs in Orange County, Los Angeles County, San Diego, the San Francisco Bay area, and other coastal communities. Windspeeds in some places reach 125 miles per hour, hurricane-force winds. Across wider areas of the state, winds reach 60 miles per hour. Hundreds of landslides damage roads, highways, and homes. Property damage exceeds $300 billion, most from flooding. Demand surge (an increase in labor rates and other repair costs after major natural disasters) could increase property losses by 20 percent. Agricultural losses and other costs to repair lifelines, dewater (drain) flooded islands, and repair damage from landslides, brings the total direct property loss to nearly $400 billion, of which $20 to $30 billion would be recoverable through public and commercial insurance. Power, water, sewer, and other lifelines experience damage that takes weeks or months to restore. Flooding evacuation could involve 1.5 million residents in the inland region and delta counties. Business interruption costs reach $325 billion in addition to the $400 billion property repair costs. This means that an ARkStorm could cost on the order of $725 billion, which is nearly 3 times the loss deemed to be realistic by the ShakeOut (AKA the next big one) for a severe southern California earthquake, an event with roughly the same annual occurrence probability.
These new shocking discoveries are another example of the need for private businesses to plan and prepare for these occurrences. Planning can help protect company assets, clients and employees from the next ARkStorm. Contact Homeland Advisory Group to find out more about your local risks.