Scientists as well as flood and water resource managers got a first-hand look at what a massive storm can do to California. On June 24, 2009, at the Extreme Precipitation Symposium at UC Davis, top scientists working on the “ARkStorm” disaster scenario presented preliminary data detailing on-going work to design a large, but scientifically plausible, hypothetical storm that will provide emergency responders, resource managers and the public a reality check on what is historically possible. The ARkStorm scenario will address massive West Coast storms analogous to those that severely impacted California in 1861/62.
“Elevating the visibility of such storms and preparing for them is particularly important in view of preliminary scientific results that suggest that the most massive of these storms may become more common and ferocious at the global climate warms,” said Michael Dettinger, a USGS Research Hydrologist at Scripps Institute of Oceanography.
Dettinger and Marty Ralph, NOAA Program Manager at Environmental Systems Research Laboratory in Boulder, Colorado, are coordinating the Atmospherics Design Section of the ARkStorm scenario and presenting preliminary findings at the symposium. The ARkStorm scenario will include contributions from experts from NOAA, USGS, Scripps, the State of California and many other organizations. Experts will examine in detail ARkStorm’s cost and its potential consequences including floods, landslides, coastal erosion and inundation, debris flows, pollution and extirpation of endangered species. Experts will further examine physical damage possibilities like bridge scour, road closures, dam failure, property loss, and levee system collapse as well as the social and economic impacts of the storm.
The term “Pineapple Express” is popularly used to describe the meteorological phenomenon that causes moisture to be drawn from the Pacific Ocean near the equator and transported to the US West Coast with fire-hose like ferocity. This meteorological phenomenon of intense wind and rain is technically associated with “extratropical cyclones.” While these cyclones are not of the simple circular patterns commonly associated with hurricanes, they do carry within them a phenomenon that is the focus of some of the most intense impacts – an “atmospherics river.” ARs have recently become observable through satellite technology.
According to Marty Ralph, “An intense atmospheric river striking the northern Sierra Nevada Mountain Range and flooding downtown Sacramento is the California analogue to Hurricane Katrina hitting the Gulf of Mexico Coast and flooding New Orleans.”
While intense ARs that produce West Coast flooding may never compare with hurricanes in the national public’s eye, they represent the West Coast analogue of hurricanes, and in key ways, Sacramento is no less at risk now than New Orleans was before Katrina. The task of ARk Storm is to elevate the visibility of the very real threats to human life, property, and ecosystems posed by extreme winter storms on the US West Coast. This enhanced visibility will help increase preparedness of the emergency management community and public to such a storm.
