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Select Accomplishments

Innovations from HMT-West support NOAA's Rapid Response to the Howard Hanson Dam flood risk.

In response to a request from the US Army Corps of Engineers (US-ACE), who were concerned about the safety of the Howard Hansen Dam on the Green River near Seattle, WA, HMT contributed to a NOAA rapid response. Building on what was learned in California, HMT deployed a number of Atmospheric River Observatories and related monitoring sites for water vapor and snow level, which supported the Seattle Weather Forecast Office and positively affected the US-ACE operations of the dam. For more information see: Howard Hanson Dam Rapid Response and NOAA's New Mobile Atmospheric River Observatory.

Development of "demonstration" performance measures for snow level and extreme precipitation predictions.

Two new demonstration performance measures have been developed, based on the HMT-west experience. They were motivated by a recognition that these are two of the top variables that drive stream flow forecasts in mountainous terrain, and are considered important by NOAA Stakeholders. They are in the process of being "base-lined" over multiple seasons and broader areas, and are applicable not only to the HMT-West domain, but also to the rest of the nation.

  • For more information on a performance metric for extreme precipitation forecasts, see the article: Ralph, F. M., E. Sukovich, D. Reynolds, M. Dettinger, S. Weagle, W. Clark, and P. J. Neiman, 2010: Assessment of Extreme Quantitative Precipitation Forecasts and Development of Regional Extreme Event Thresholds Using Data from HMT-2006 and COOP Observers. J. Hydrometeor., (In press), doi:10.1175/2010JHM1232.1.
  • For more information on the snow level performance metric, see: White, A. B., D. J. Gottas, A. F. Henkel, P. J. Neiman, F. M. Ralph, and S. I. Gutman, 2010: Developing a Performance Measure for Snow-Level Forecasts. J. Hydrometeor., 11, 739-753, doi:10.1175/2009JHM1181.1.
  • Note that the snow level algorithm, upon which the snow level performance measure is built, received the 2003 NOAA Bronze Medal Award, the 2003 CIRES Outstanding Research Performance Award, and was awarded a U.S. Patent #6,615,140

Atmospheric river real-time monitoring and prediction tool invented and demonstrated.

This past year, a prototype Coastal Atmospheric River Monitoring and Early Warning System (aka "the flux tool") underwent demonstration trials. This decision support tool brings together detailed observations and mesoscale model data for comparison with science-based thresholds that objectively identify AR conditions and extreme AR conditions capable of producing flooding. This tool provides enhanced situational awareness and forecast guidance for extreme precipitation events along the US West Coast. For more information see: Coastal Atmospheric River (AR) Monitoring and Early Warning System and Neiman et al. 2009.

  • The flux tool received the NOAA Administrator's Bronze Medal Award in 2009

Forecast aid developed by HPC focused on horizontal water vapor flux.

NOAA NCEP HPC developed a suite of forecast decision aids known as standardized anomalies (often referred to as "flux anomaly tools"). These tools provide statistical insight into the potential severity of a weather system. Within the context of HMT, the moisture flux tools have proven particularly useful to forecasters and scientists who are looking at storms moving off of the Pacific and making landfall on the West Coast. For more information see: Using Standardized Anomalies in Operational Forecasting.

Interactive, near real-time QPF verification tools developed through collaboration with DTC.

A collaboration between HMT and the Developmental Testbed Center (DTC) has created a suite of interactive QPF verification tools. These tools permit a user to evaluate the performance of HMT and operational forecast products, both during the season in near real-time and retrospectively. This new capability is helping HMT partners to quantify the performance of new forecast tools, such as the high-resolution WRF ensemble models. For more information see: DTC/HMT Verification Overview.

Key HMT-West findings are being implemented in California through a major partnership with the State's Department of Water Resources (DWR).

Through a 5-year MOU between NOAA and DWR, several key innovations from HMT are being implemented long-term. These include new observations, modeling and display methods and development of a decision support tool for extreme precipitation and other hydrologic forcing. The initial water vapor, soil moisture and snow level observations are now operating, while modeling methods, including ensemble and high resolution techniques suited to cool-season orographic precipitation are being tested and the scientific foundations for the decision support tool have been laid around the atmospheric river phenomenon. .

Field experiments document gaps in current capabilities and explore new radar methods ranging from better use of existing radar data to polarimetric algorithms for QPE and gap-filling radar technologies.

  • Field experiments have documented a shallow rainfall process, referred to as "non bright-band" (NBB) rain, that can produce significant rainfall at altitudes below current NEXRAD scan coverage in many locations in the western U.S. Significant errors in NEXRAD-based QPE result from the radar's overshooting these regions, but even when the radars sample NBB rain, the drop-size distributions are so different than the standard NEXRAD algorithms that QPE estimates are biased very low.
  • Distinct examples of these problems were crucial in motivating a San Francisco TV station to install their own radar to help fill the gap in NEXRAD coverage over the flood-prone Napa and Sonoma river basins. This "KPIX" radar has been a test of the concept of integrating private sector, gap-filling radars, into NWS forecast operations in the Monterey Weather Forecast Office.
  • A more general problem also associated with vertical coverage of NEXRAD, has been identified. It is associated with beam broadening and the increasing altitude of the lowest beam with increasing range from the radar. A technique has been developed to correct for the "vertical profile of reflectivity," and has been implemented in NSSL's Q2 system, which is now being used in QPE nationally.
  • Finally, state-of-the art methods are being tested using NOAA/PSD's X-Pol scanning polarimetric radar, which has documented the capabilities and limitations of X-band and polarimetric radar for improved QPE in complex terrain.

Reforecast method implemented at NCEP is used by HPC for QPF, and next generation version is under development.

A next-generation reforecast data set is currently in preparation using a supercomputer at the Department of Energy's Lawrence Berkeley Lab. A reforecast is a retrospective forecast of the weather. In the first-generation reforecast created at ESRL, a 15-member ensemble forecast out to 15 days lead was generated with a reduced-resolution version of the NCEP global model for every day from 1979 to present. When the same forecast model is run in real time, systematic errors of the model can be diagnosed and corrected using the past forecasts and their relationship to the observed weather. This has proven very useful for improving quantitative precipitation forecasts. A real-time web page of statistically adjusted precipitation forecasts from the first-generation reforecast is available at, and a description of the reforecasts is available in Hamill et al. (2006). The next-generation reforecast will be computed during late 2010 and early 2011, using a version of the NCEP global model that will be operational in 2011. The model will have four times greater resolution than the first-generation reforecast model, and much more data will be saved and made available, making it more useful to hydrologists and other users.

  • Reference: Hamill, T. M., J. S. Whitaker, and S. L. Mullen, 2006: Reforecasts, an important dataset for improving weather predictions. Bull. Amer. Meteor. Soc., 87,33-46, doi:10.1175/BAMS-87-1-33.

Peer reviewed publications document HMT's scientific and technical innovations.

HMT has led to a wide range of innovations ranging from better scientific understanding to new tools, all inspired by hydrometeorological applications. A core value of HMT is to ensure that these advances pass the time-proven test of peer review for scientific and technical merit, which strengthens the credibility of NOAA's hydrometeorological services. HMT, and its precursors - CALJET and PACJET, have produced 50 peer-reviewed scientific journal publications. See: An Analysis of the HMT Bibliography, which is a convenient documentation of HMT's contributions to the field.