On the operational use of an enhanced observing network for the Howard Hanson Dam hazard

In response to an elevated flood potential downstream of the Howard Hanson dam on the Green River that became apparent after a January, 2009, significant flood event, a coordinated effort was implemented by local and federal agencies in order to facilitate Decision Support Services (DSS) for the areas affected by this basin in future, significant precipitation and flood events.

In order to better support the Howard Hanson dam DSS effort, a wide range of additional operational resources were brought to bear by NOAA and the National Weather Service, including a significant, enhanced observing network distributed not only in and around the Green River Basin, but throughout western Washington.

These additional observational resources included the installation of an enhanced rain gage network as well as the deployment of two Atmospheric River Observatories in partnership with NOAA's Office of Atmospheric Research (OAR). New rain gage instrumentation was installed in optimal locations to fill data gaps, or at locations where an observation site had been lost, and communication capabilities and/or data ingest at existing sites were upgraded to improve access and reliability of data during an event. Also, to supplement the installation of an ARO system in Grays Harbor County that was deployed as a part of the Hydromet Testbed (HMT) program, a second observatory was “split” to optimize its benefit to Green River forecasts. The wind profiler, water vapor sensor, and weather station were installed just southwest of the basin (in Pierce County) to better estimate the flow of moisture toward the Green River basin. The S-Prof vertically-pointing radar was installed near the Howard Hanson Dam to monitor the local rain/snow level.

The new data are being used in forecast and warning operations and being made available to other interested parties, including the USACE and local emergency management officials. This presentation will give an overview of the data assets as well as their operational use during the 2009-2010 season, as well as plans for the upcoming season.