SPC’s Storm-Scale Ensemble of Opportunity (SSEO) Continues Where the High-Resolution Mid-Atlantic Forecasting Ensemble (HME) Left Off

SSEO Membership – The 00Z SSEO is a multi-model, multi-physics ensemble comprised of 7 members with initial condition diversity from 2 time-lagged members.

The Storm Prediction Center (SPC) has developed the storm-scale ensemble of opportunity (SSEO) as an alternative to the creation of a computationally expensive storm-scale ensemble system (note that the SSEO web page appears to work best outside of IE).  Instead of creating a new ensemble system, the SSEO takes advantage of seven deterministic convection-allowing model runs already available to the SPC. The data from these runs are processed as an ensemble to generate ensemble fields such as mean, maximum, and exceedance probabilities. In addition, the SSEO generates select hourly maximum storm-attribute fields, such as simulated reflectivity, updraft helicity, updraft speed, and 10‐m wind speed. A few example images of the SSEO products are shown below. The SSEO is available at 00 UTC each day and includes the seven members detailed above.  Subjective and objective results during the 2012 Spring Forecasting Experiment indicate that the SSEO provides useful information for severe convection forecasting and compared favorably to two formal storm-scale ensemble systems – the SSEF and the AFWA.

Example SSEO products.

The High-Resolution Mid-Atlantic Forecasting Ensemble (HME) was a federated effort to improve operational forecasts by utilizing data and computing resources from a diverse group of cooperating institutions in order to create a mesoscale ensemble from independent members.  The HME was partially supported by the current CSTAR project. The HME combined 9 existing deterministic convection-allowing model runs produced by 9 WFOs in the NC State CSTAR domain.  The HME system was produced from these runs and 12 other runs provided by a University and two national laboratories including a run provided by the National Severe Storms Laboratory that is a part of the SSEO.  The coordination, synthesis, and dissemination of the ensemble information was performed by the Renaissance Computing Institute (RENCI) at the University of North Carolina-Chapel Hill.

Unfortunately the HME is no longer being generated because changes in staffing and the loss of key computational resources and archived data at RENCI. While it is disappointing that the HME is no longer operating, what was accomplished is noteworthy. A group of more than a half dozen WFOs and other partners worked together to build a near operational ensemble, a remarkable accomplishment. Valuable lessons were learned on how to make this type of project more successful in the future and a greater understanding of NWP was gained by the participating offices.  At the 3rd International Joint Topical Meeting on Emergency Preparedness & Response and Robotics & Remote Systems conference in Knoxville, a paper entitled “High-Resolution Atmospheric Ensemble Modeling at SRNL” by Robert Buckley and coauthors was presented that discussed the development and use of the High-Resolution Mid-Atlantic Forecasting Ensemble (HME).  ( http://sti.srs.gov/fulltext/SRNL-STI-2010-00777.pdf).

While there is no direct connection between the SSEO and the HME, they both had similar goals. The HME struggled because of limitations with its web display and getting the products into forecaster’s hands in AWIPS.  The SSEO appears to be building upon the success of the Spring Forecasting Experiments and the SPC web site. Given the apparent success of the SSEO and at least one common ensemble member, a little bit of the HME lives on in the SSEO.

The SPC Storm-Scale Ensemble of Opportunity: Overview and Results from the 2012 Hazardous Weather Testbed Spring Forecasting Experiment. Israel L. Jirak, NOAA/NWS/NCEP/SPC, Norman, OK; and S. J. Weiss and C. J. Melick.  26th Conference on Severe Local Storms.

More information on the SSEO –

More information on the HME –

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2 Responses to SPC’s Storm-Scale Ensemble of Opportunity (SSEO) Continues Where the High-Resolution Mid-Atlantic Forecasting Ensemble (HME) Left Off

  1. Pingback: Arkansas tornado outbreak amazingly well-forecast, despite horrifying outcome

  2. Pingback: Arkansas tornado outbreak amazingly well forecast, despite horrifying outcome - Washington Post (blog) 2014

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