Flood hazard monitoring in Colorado mountains with mobile Doppler radars [INVITED]

Keen interest in improved observation of precipitation during the summer months has resulted in two years of field projects in the Colorado Rocky Mountains. These projects have been supported by several state and local agencies with stakes in water issues including the Colorado Water Conservation Board, Colorado Division of Emergency Management, and the Southwestern Water Conservation Disctrict. The overall objective is to build a science framework and business case for additional radars for improved precipitation observations through the use of mobile Doppler radars. The 2009 Gunnison field project was conducted between 15 July through 20 September in Gunnison County. The NOAA/NSSL X-band dual-polarized (NOXP ) mobile Doppler radar and the C-band single-polarization Shared Mobile Atmospheric Research and Teaching – Radar (SMART-R) collected data. Both mobile radars observed high-resolution precipitation structures within the storms especially close to the surface and within mountain valleys while the closest WSR-88D radar at Grand Junction was mostly blocked over this region. Surface observations were augmented the National Center for Atmospheric Research's network of nine recording tipping bucket rain gauges measuring rain intensity and the University of Colorado's two optical disdrometers measuring particle size distribution and fall velocity. Successes of the Gunnison project lead to support for a flood hazard monitoring project in southwest Colorado during August of 2010. The Southwest Colorado radar project (SWCO) involved providing near-realtime precipitation information to NWS Weather Forecast Offices to assess the potential benefit of additional radar observations for flash flood warnings using the Flash Flood Monitoring and Prediction system. The primary area of interest was the San Juan Mountains and many river basins that were vulnerable to debris flows as the result of the 2002 Missionary Ridge fire. The C-band dual-polarized SMART-R2 was located on Bridge Timber Mountain southwest of Durango. This location allowed coverage of a large radar coverage gap in the 4 Corners region in addition to the focus on the San Juan Mountains. In addition, the National Center for Atmospheric Research provided a network of seventeen recording tipping bucket rain gauges and the University of Colorado provided two disdrometers and a vertically-pointing microwave rain radar. This invited paper presents results from these field projects.