California Adds Record Snowpack: Is the Drought Over?

December 28, 2021

Short answer no.
General consensus that 10 years of above-average precipitation would be needed to bring the west back to “normal”, or at least the norms of the 80s and 90s, when so much development took place.

There is a nagging question that a friend brought to mind this morning.

Current snow pack being fed by a series of “Atmospheric River” events. California has in the not so distant past seen what is known as the “Ark Storm”, ( ARK for Atmospheric River K – “K” meaning a thousand year event – which we know is no longer a thousand year event).

In 1861, a very deep snowpack was disrupted by a torrential spring rain, resulting in the destruction of a number of communities.

US Geological Survey:

This document summarizes the next major public project for MHDP, a winter storm scenario called ARkStorm (for Atmospheric River 1,000). Experts have designed a large, scientifically realistic meteorological event followed by an examination of the secondary hazards (for example, landslides and flooding), physical damages to the built environment, and social and economic consequences. The hypothetical storm depicted here 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.

Extensive flooding results. In many cases 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, meaning 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 authors for a severe southern California earthquake, an event with roughly the same annual occurrence probability.

Winter storms of 1861-1862. Beginning in early December 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, forcing the state capitol to be moved temporarily from Sacramento to San Francisco, and requiring Governor Leland Stanford to take a rowboat to his inauguration. William Brewer, author of “Up and down California,” wrote on January 19, 1862, “The great central valley of the state is under water-the Sacramento and San Joaquin valleys-a region 250 to 300 miles long and an average of at least twenty miles wide, or probably three to three and a half millions of acres!”

The 1861-62 series of storms were the largest and longest California storms in the historic record, but were probably not the worst California has experienced. Geological evidence indicates that floods that occurredbefore Europeans arrived were bigger.

Scientists looking at the thickness of sediment layers collected offshore in the Santa Barbara and

San Francisco Bay areas have found geologic evidence of megastores that occurred in the years 212, 440, 603, 1029, 1418, and 1605, coinciding with climatological events that were happening elsewhere in the world.
There is no scientific evidence to suggest that such extreme storms could not happen again.

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: