Impact of recent extreme Arizona storms

Abstract

Heavy rainfall on 27–31 July 2006 led to record flooding and triggered an historically unprecedented number of debris flows in the Santa Catalina Mountains north of Tucson, Ariz. The U.S. Geological Survey (USGS) documented record floods along four watercourses in the Tucson basin, and at least 250 hillslope failures spawned damaging debris flows in an area where less than 10 small debris flows had been documented in the past 25 years. At least 18 debris flows destroyed infrastructure in the heavily used Sabino Canyon Recreation Area (http://wwwpaztcn.wr.usgs.gov/rsch_highlight/articles/20061 l.html). In four adjacent canyons, debris flows reached the heads of alluvial fans at the boundary of the Tucson metropolitan area. While landuse planners in southeastern Arizona evaluate the potential threat of this previously little recognized hazard to residents along the mountain front, an interdisciplinary group of scientists has collaborated to better understand this extreme event.

The Relationship of Transient Upper-Level Troughs to Variability of the North American Monsoon System

“…Though much fewer in number, on average, these types of IVs can sometimes become cut off from both the polar westerlies and tropical easterlies and supply the forcing mechanism for catastrophic amounts of monsoon rainfall. A good example of this type of event would be one that occurred on 27-31 July 2006 when Tucson, Arizona, experienced a serious flooding event underneath a cutoff upper-level disturbance (Magirl et al 2007). This system was an upper-tropospheric low that moved down the east side of the monsoon ridge and became cut off over the state of Arizona for four days.…”

Objective Climatological Analysis of Extreme Weather Events in Arizona during the North American Monsoon

“…Even though Tucson is a semiarid climate, on rare occasions PWV values can exceed 50 mm, values that are reminiscent of a deep tropical environment such as the Amazon rain forest (Adams et al 2013). Documented severe-flooding events during the monsoon in Arizona-for example, the Sabino Canyon flood in Tucson-have values of PWV on this order (Magirl et al 2007;Griffiths et al 2009).…”

Analyzing debris flows with the statistically calibrated empirical model LAHARZ in southeastern Arizona, USA

“…Point rainfall measurements indicated that 6-h rainfall locally was as high as 105 mm and had recurrence intervals (RI) of 250 years (Magirl et al, 2007). Using weather radar calibrated to an array of recording rainfall gages, Griffiths et al (2009) modeled rainfall for 754 grid cells about 1 km 2 in size in the Santa Catalina Mountains.…”

“…2). Sabino Canyon, a heavily used recreation area administered by the U.S. Forest Service, was the epicenter of mass wasting, where debris flows removed structures, destroyed the roadway in multiple locations, and closed public access for months (Magirl et al, 2007).…”

“…A week of heavy rainfall in southeastern Arizona in late July 2006 caused 435 slope failures and numerous debris flows in the Santa Catalina Mountains in southeastern Arizona (Magirl et al, 2007). In five canyons draining southward from the Santa Catalina Mountains, debris flows reached or passed the heads of alluvial fans on the edge of the Tucson metropolitan area causing significant damage to infrastructure and aggrading channels managed for flood conveyance.…”