GSD and DTC meet major NWP milestones

Image of HWRF Wind Forecast model of hurricane Matthew superimposed over satellite image. Both are images of the Florida panhandle.

HWRF wind forecast for Hurricane Matthew

October 24, 2017

GSD and Cooperative Institute researchers met major milestones recently that allow scientists outside of the National Weather Service (NWS) to develop and assess innovations in Numerical Weather Prediction (NWP). The team is part of the Developmental Testbed Center (DTC) that supports the NWP community in NOAA research laboratories and academia.

The DTC released two codes that are used to combine weather observations from a variety of sources including data from satellites and radars. The Community Gridpoint Statistical Interpolation (GSI) version 3.6 and the Community Ensemble Kalman Filter (EnKF) version 1.2 use these observations to represent the state of the atmosphere at a given time.  A high-quality data analysis is critical for producing accurate forecasts, and GSI and EnKF are used by National Centers for Environmental Prediction (NCEP) operational modeling systems.

Another release by the DTC was the community Hurricane Weather Research and Forecast (HWRF) V3.9a modeling system that is designed to serve both operational forecasting and atmospheric research needs. The HWRF system is a coupled atmosphere-ocean model used for tropical cyclone research and forecasting in all Northern and Southern Hemisphere ocean basins.  The latest HWRF code includes the capability to use new weather observations collected by satellites and Hurricane Hunter aircraft to improve the model forecast. Researchers also improved how the model represents drizzle, thunderstorms, and the exchange of energy between the ocean and the atmosphere, and provided more details on how the atmosphere and ocean change with height and depth, among other upgrades.

The public releases of these codes are the culmination of extensive research and documentation and include training materials and a help desk. The GSI and EnKF community codes have more than 1900 registered users, while the HWRF community has 1500 registered users, representing a robust distributed effort in model development and transition of innovations to operations.

The DTC, in collaboration with Environmental Modeling Center (EMC), will be hosting an in-person tutorial on the HWRF system. It will be held January 23–25, 2018 at the NOAA Center for Weather and Climate Prediction (NCWCP) in College Park, MD. Registration, a draft agenda, information about hotel accommodations, and other logistics can be found on the tutorial website: 2018 HWRF tutorial

Prospective contributors can also apply to the DTC visitor program for their data assimilation and HWRF research and code transition. The visitor program is open to applications year-round. Please check the visitor program webpage ( for the latest announcement of opportunity and application procedures.

The DTC is a distributed facility, with a goal of bridging the research and operational communities. The above code releases are sponsored by the National Oceanic and Atmospheric Administration (NOAA) and the National Center for Atmospheric Research (NCAR). NCAR is supported by the National Science Foundation (NSF).

For more information about GSI, EnKF, HWRF, and the other community codes supported by the DTC, please visit

For more information about this article, contact: Susan Cobb 303-497-5093