ARkStorm - Navigating the Atmospheric Rivers
Dale Alan Cox
October 7, 2011

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985 Lincoln Way
Auburn, CA 95603
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Beginning on Christmas Eve, 1861, and continuing into early 1862, an extreme series of storms lasting 45 days struck California.Great flood of 1861-1862, all of Sacramento floods. On January 21, 1962 The New York Times reported, " All Sacramento City, save a small part of one street, part of Marysville, part of Santa Rosa, part of Auburn, part of Sonora, part of Nevada, and part of Napa, not to speak of less important towns, were under water....The North Fork of the American River at Auburn rose thirty-five feet, and in many other mountain streams the rise was almost as great."

The storms caused severe flooding, turning the Sacramento Valley into an inland sea. Spontaneous lakes popped up in the Mojave Desert and Los Angeles basin. Nearly a third of the young state's taxable land was destroyed.

The 1861-62 series of storms were probably the largest and longest California storms on record. However, geological evidence suggests that earlier, prehistoric floods were likely even bigger. The winter storm scenario "is much larger than anything in living memory," explains project manager Dale Cox with the U.S. Geological Survey.

The ARkStorm storm is patterned after the 1861–62 historical events but uses modern modeling methods and data from large storms in 1969 and 1986. The ARkStorm draws heat and moisture from the tropical Pacific, forming a series of Atmospheric Rivers (ARs) that approach the ferocity of hurricanes and then slam into the U.S. West Coast over several weeks.

The "AR" stands for "Atmospheric River", the "k" for 1,000 (like a 1-in-1000 year event), and of course "ARkStorm" is meant to summon visions of biblical-scale deluge, similar to the great flood of 1862.

Atmospheric rivers could cause 45 days of rain "Atmospheric Rivers" was a term coined in the 1990s to describe plumes of moisture that ride up out of the subtropics into the mid-latitudes along the axis of a cold front.

Traditional water vapor satellite imagery does not show these plumes very well, and it was only when microwave satellite imagery from polar orbiting satellites became available in the late 1990s that the full importance of these Atmospheric Rivers came to be revealed. Atmospheric Rivers account for a significant portion of California's cold season rainfall and snowfall.

Over the last 1,800 years,the geologic record shows at least six storms worse than the 1861-1862 storms in California. If the planet continues to warm, as expected, the odds of such an event will at least double by 2100, due to the extra moisture increased evaporation from the oceans will add to the air.

Jeffrey Mount, director of the Center for Integrated Watershed Science and Management at the University of California at Davis, said in a recent interview with MSNBC, "The chances of a catastrophic flood occurring in the Sacramento-San Joaquin Delta sometime in the next 50 years are about two out of three." He called Sacramento, which is only protected to a 1-in-80 year flood by its levees, "the most at-risk large metropolitan area in the country, with less than half the protection that New Orleans had. It is at extreme risk due to levee failure and subsidence."

The U.S. Geological Survey, Multi Hazards Demonstration Project (MHDP) uses hazards science to improve resiliency of communities to natural disasters (including earthquakes, tsunamis, wildfires, landslides, floods and coastal erosion). MHDP assembled experts from the National Oceanic and Atmospheric Administration (NOAA), USGS, Scripps Institute of Oceanography, the State of California, California Geological Survey, the University of Colorado, Federal Emergency Management Agency (FEMA), the National Center for Atmospheric Research (NCAR), California Department of Water Resources, California Emergency Management Agency (CalEMA) and other organizations to design the large, but scientifically plausible, hypothetical storm scenario. The project engages emergency planners, businesses, universities, government agencies, and others in preparing for major natural disasters. The project also helps to set research goals and provides decision-making information to emergency responders, resource managers, and the public.

Doors open at 7pm, presentation starts at 7:30pm. 
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About Dale Alan Cox

Dale Alan Cox of the USGS Multi-hazards project Dale A. Cox is the Chief of Staff for the USGS Pacific Southwest and Region IX Lead of the Department of Interior, Regional Emergency Coordination Council.

He was formerly the Project Manager USGS Multi-Hazards Demonstration Project (MHDP) where he led ARkStorm, the disaster scenario that explored modern impacts to a storm analogous to those that impacted California in 1861/62.

Cox coordinated the work of over 300 scientists and experts in 2008 to create the ShakeOut Earthquake Scenario, the most comprehensive earthquake scenario ever created. He is one of the creators of the “The Great ShakeOut” and winner of the 2009 Shoemaker Award for Communications Excellence.

Mostly recently, Cox coordinated the 2010 Tsunami Summit in an effort to improve community resiliency in the Pacific. Cox also coordinated the USGS 2007 Firestorm Response that included ash chemical analysis, endangered species assessment and recovery, and a real-time debris flow warning system completed in time for the first rains.

Dale A. Cox joined the US Geological Survey in 1994, where he surveyed and reported on the hydrologic conditions of the High Plains Aquifer. While in Nebraska, he helped to create Groundwater Guardian, an international collaborative partnership between the USGS and the Groundwater Foundation. Cox later served as Chief of Communications at the USGS California Water Science Center, where he coordinated the Lake Tahoe Presidential Forum and the bathymetric mapping of Lake Tahoe.

Cox also helped to coordinate the National Oceans Conference, another presidential forum to raise awareness and develop global partnerships to tackle ocean issues. Later, Cox was served as the USGS Western Publishing Manager.

Scroll down to learn more about this topic below - including Fox 40 news coverage of the U.S. Geological survey 2-day seminar in Sacramento in January!


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