NSSL Hot Item

NSSL’s SMART-Radar team deployed to help improve debris flow warnings

The NSSL Shared Mobile Atmospheric and Research Teaching Radar (SMART-R) team is preparing for its fourth deployment as part of the NOAA and U.S. Geological Survey Demonstration Flash Flood and Debris Flow Early Warning System project.

The 2008-2009 Debris Flow project will run from December 1, 2008 through February 28, 2009 and is focused on helping forecasters improve flash flood and debris flow warnings in areas damaged by wildfires.

The focus of this years effort is the “Gap Fire” burn area near Santa Barbara, California in the rugged Los Padres National Forest. The human-caused fire started on Tuesday, July 1 2008, and wasn’t fully contained until July 28 2008. The wildfire burned 9,443 acres and destroyed 4 outbuildings, but no homes.

Through a NOAA/HPCC grant, NSSL recently upgraded the SMART-R with a revolutionary satellite-based, ultra-high bandwidth Internet dish system allowing real-time transmission of full-volume radar data back to the Hazardous Weather Testbed in Norman, OK and into NSSL’s “Q2”, or National Quantitative Precipitation Estimation system. The gridded SMART-R reflectivity and estimated one-hour rainfall over the research fire area will then be relayed to the NWS/Oxnard forecast office where it will be used as part of their flash flood monitoring and prediction system. Rainfall thresholds for burn area debris flows have been provided by the USGS so warnings can be issued if rains exceed the threshold for intensity or duration. Following the project research will be performed using the radar-derived rainfall to refined the rainfall thresholds.

During the project, the SMART-R delivers reflectivity and estimated one-hour rainfall over the research fire area. The USGS has heavily instrumented the burn area to measure the amount of debris that comes down the canyon during a rainstorm. During 2007-2008 operations, the Oxnard, CA National Weather Service Forecast Office used SMART-R data in their decision to issue a flash flood warning during the significant storm of January 5-7, 2008. The Gap Fire area is not well covered by existing WSR-88D radars due to the rugged topography. This year the SMART-R data will be delivered via a satellite-based internet system from an antenna mounted on the cab of the SMART-R to a server in Norman that will bring it into the labs “Q2” or national Quantitative Precipitation Estimation system. The gridded data will then be relayed to the NWS/Oxnard forecast office where it will be used as part of their flash flood monitoring and prediction system. Rainfall thresholds for burn area debris flows have been provided by the USGS so warnings can be issued if rains exceed the threshold for intensity or duration. Following the project research will be performed using the radar-derived rainfall to refined the rainfall thresholds.

When data is being collected, quasi-real time SMART-R Imagery of reflectivities and velocities can be seen at http://smartr.metr.ou.edu/~hmt/. More information about the SMART-R deployment can be seen at the NSSL site: http://www.nssl.noaa.gov/debrisflow08/

Background: Areas damaged by wildfires are known as burn scars and are particularly susceptible to flash floods and debris flows during rainstorms. Rainfall that is normally absorbed by vegetation can run off almost instantly, causing creeks and drainage areas to flood much earlier and with higher magnitude than normal.

Significance: Results from the Flash Flood Demonstration and Debris Flow project will help public and emergency responders determine flash flood and debris flow hazards in the post-wildfire environment and better serve society’s need for weather and water information.