Evaluation of retrospective forecasts from 2010 HFIP Stream 1.5 candidates

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Wednesday, 26 January 2011
Evaluation of retrospective forecasts from 2010 HFIP Stream 1.5 candidates
Christopher L. Williams, NCAR, Boulder, CO; and L. Nance, B. G. Brown, K. Crosby, M. Harrold, T. L. Jensen, and P. A. Kucera

The Hurricane Forecast Improvement Project (HFIP) provides the basis for NOAA and other agencies to coordinate hurricane research needed to significantly improve guidance for hurricane track, intensity, and storm surge forecasts. HFIP uses the term “Stream 1” to refer to the yearly upgrades made to operational numerical weather prediction (NWP) capabilities, and the developmental and test activities supporting them. HFIP terms efforts taking multiple years to enhance operations as “Stream 2”. In 2009, HFIP and the National Hurricane Center (NHC) agreed to establish a new, intermediate pathway to operations known as “Stream 1.5”. Stream 1.5 covers experimental models and/or techniques that NHC, based on prior assessments, wants to access in real-time during a particular hurricane season, but which cannot be available in conventional “production” mode. Stream 1.5 projects will be run as part of HFIP's annual summertime “Demonstration Project”. To qualify, participation by a candidate project must be approved by HFIP management and the NHC. Part of the basis for this approval is demonstrated performance through extensive retrospective testing. Objective verification for the 2010 Stream 1.5 candidates was conducted by the Tropical Cyclone Modeling Team (TCMT) located in the Joint Numerical Testbed Program of the National Center for Atmospheric Research's Research Applications Laboratory. The goals of the 2010 retrospective testing are to (1) provide adequate statistics for assessing the skill of the model candidates, (2) help identify modeling systems to be included in the HFIP Stream 1.5, and (3) provide information that may help to calibrate the multi-model ensemble forecasts for 2010. The retrospective testing focused on a representative sample of 27 storms from the 2008 and 2009 hurricane seasons. Four modeling groups participated in the retrospective testing. The models included two configurations of the Weather Research and Forecasting (WRF) model, a new version of the GFDL model, and the Navy's tropical cyclone model. This presentation will provide an overview of the 2010 retrospective testing, a summary of the differences in track and intensity errors for the comparisons of the individual participating models to the operational GFDL model, and a review of the impact of including the forecasts from the Stream 1.5 candidates as part of the conventional consensus forecast. The retrospective testing verification effort and follow-on work will be used to guide future HFIP activities and contribute to the continuing HFIP effort to improve tropical cyclone intensity and track forecasts by providing feedback to the forecasting and modeling groups.