National Weather Service United States Department of Commerce

fcd logoThe Flood Control District of Maricopa County The Flood Control District of Maricopa County operates a 24-hour rain, stream and weather gage network which provides "real-time" information to the County and many other agencies about rainfall, floods, and weather conditions in Maricopa County. The information provided by the ALERT (Automated Local Evaluation in Real Time) system is important to the District and other agencies because occasional heavy rainfall can generate stream flows which significantly impact flood control facilities such as dams and channels. The Flood Control District started the ALERT system in 1980 after the late-1970s floods. Gages were first placed to monitor the major rivers, then later installed on District dams and flood control structures. After the 1993 floods, the District started placing more gages in smaller washes and upstream of unbridged road crossings. Currently, the District has around 300 automatic rain gages, 170 automatic stream gages and 35 automatic weather stations throughout Maricopa and neighboring counties.

Phoenix Rainfall Index Historically, the "official" rain gage for the Phoenix Metropolitan Area has been situated near the center of the city. Since 1953, the official rain gauge has resided at Phoenix Sky Harbor International Airport (KPHX). While KPHX may have adequately represented Phoenix for the first half of the 20th century, it has become apparent that a single observation station can no longer properly represent the spatial and temporal distribution of precipitation over the city, especially during single day summer thunderstorm events associated with the North American Monsoon. In order to better represent rainfall across the city, and compare and contrast precipitation events, a Phoenix Rainfall Index (PRI) was created. Based on precipitation observed at up to 132 ALERT rain gauges across the city (operated by the Flood Control District of Maricopa County), the PRI incorporates both spatial coverage and intensity of precipitation.

Regional Temperature and Precipitation Report Provides updated observations of maximum and minimum temperatures and precipitation at numerous sites. Data are collected from a combination of volunteer observation sites and automated weather observation stations. This product is disseminated twice daily, at 9:00 AM and 6:00 PM.

CoCoRaHS (AZ) / CoCoRaHS (CA) CoCoRaHS is a grassroots volunteer network of backyard weather observers of all ages and backgrounds working together to measure and map precipitation (rain, hail and snow) in their local communities. By using low-cost measurement tools, stressing training and education, and utilizing an interactive Web-site, our aim is to provide the highest quality data for natural resource, education and research applications. The only requirements to join are an enthusiasm for watching and reporting weather conditions and a desire to learn more about how weather can effect and impact our lives.

logoArizona Flood Warning and Drought Monitoring Web Page In January 1993, heavy precipitation caused extensive flooding in many areas of Arizona and resulted in hundreds of millions of dollars in damage. During the floods, local response efforts were hindered by poor coordination among agencies and by a lack of information on the flood threat. A number of local and state agencies routinely monitor the flood threat using individual networks of automated precipitation and stage gages, weather stations, radar data, and satellite imagery, but the means to share this information was limited. In response to the lack of inter-agency communication links, these agencies formed a Multi-Agency Task Force and have met regularly since 1994 to improve flood threat assessment and communications. In 1997, the U.S. Army Corps of Engineers and the Arizona Department of Water Resources (ADWR) sponsored the design and construction of the Arizona Flood Warning System (AFWS). The project goals were to 1) improve data collection of existing real-time precipitation and stage gage networks in Arizona; 2) strengthen or establish communication links among agencies for better data dissemination and coordination; and 3) expand coverage through installation of additional gages and repeaters. Design and construction of the system was completed in 2001 and included the installation of 58 additional precipitation and stage gauges, and 5 new repeaters. The system also included a communications network and base stations at 11 Arizona counties. Since completion of the initial project, ADWR and other local member agencies have continued to enhance the system through installation of additional gages and repeaters, field maintenance, routine computer hardware and software upgrades, and regular coordination during Multi-Agency Task Force meetings.

logoAdvanced Hydrological Prediction Service The Advanced Hydrologic Prediction Service (AHPS) provides information and products provided through the infusion of new science and technology. This service improves flood warnings and water resource forecasts to meet diverse and changing customer needs. Precipitation maps are provided for the entire lower 48 states using a combination of quality controlled rain gage and radar-derived rainfall data.