Scottsdale Adverse Weather Plan (AWP) – City of Scottsdale
Scottsdale, Arizona

The City of Scottsdale, Arizona has been plagued by the multiple problems of damaging micro-burst windstorms, damaging lightning and flash floods produced by summer monsoon thunderstorms.  Often, severe weather events occur simultaneously, creating excessive stress on City emergency response agencies.

An added factor has been the explosive growth northward of the City into areas of previously undeveloped alluvial fans and low-lying hills and small mountains.  The complex terrain has enhanced the challenges to develop effective warning criteria and evacuation routines that produce a safe environment.

To address the City’s concerns, HDR meteorologists are developing a creative AWP that relies on active interaction of the local emergency response community, the Flood Control District of Maricopa County’s Meteorological Services Program (MSP) and the National Weather Service (NWS) Forecast Office in Phoenix, Arizona.  The plan will rely on GIS based information streams from the NWS WSR-88D Doppler radar in Phoenix, the Flood Control District’s Flood Detection Network (FDN) and the various NWS and MSP weather watches, warnings and basin-specific quantitative precipitation forecasts to provide adequate lead-time in the City’s fast response basins.  A detailed inventory of the city’s emergency response agencies revealed that the spontaneous nature of thunderstorm development in the desert southwest often resulted in little or no lead-time for agencies to respond proactively.  Creative use of the NWS WSR-88D radar will mesh radar reflectivity and base velocity observations with GIS-generated “electronic fences” to alert the agencies to the developing thunderstorm threats.  Combined with routine NWS and MSP forecasts a three-tiered level of readiness will be determined and linked to proactive emergency responses. 

HDR conducted an intense three-hour tabletop flood and severe weather exercise with the City’s key agencies that identified the need for enhanced information streams keyed to decision-making.  Lack of communication between agencies during events often created “black-holes” that were identified and resolved during the interactive exercise.  The need for effective evacuation routines along the Indian Bend Wash that dissects the populated southern third of the City and along several newly populated washes in the northern third of the City were discussed and are being addressed in the plan.

The plan is evolving into both a hard-copy and electronic plan.  The development of a hard copy plan will be supplemented by short-form versions of the plan for use in vehicles by police and fire.

The electronic version of the plan will provide displays of radar, weather, lightning, rainfall, stream flow and predictive information.  Additionally, the information flow will be integrated into the Arizona Flood Warning System’s (AZFWS) weather information scheme.  Ideally participation in this network will allow real-time City dispatcher reports of adverse weather to the NWS.

This information will be integrated with the City’s GIS database to assist in effective decision-making before and during severe weather and flooding events.  GIS based hydrologic basin response information and locations of key facilities are expected to result in improved decision-making during events.