A long-time focus in numerical modeling of the atmosphere has been the development and improvement of capabilities that can simulate the conditions that dictate the weather. Such systems are typically called “mesoscale” atmospheric models, where mesoscale refers to the spatial dimension over which most of the weather that influences daily, human activity occurs. NCAR has been developing a new numerical weather prediction (NWP) model that is now coming into its own: the Weather Research and Forecasting Model (WRF).⁶ WRF is employed worldwide with the largest number of registered users (over 3,700) for any such model today.

The WRF model is different from existing NWP technologies in a number of ways. Rather than created by a single researcher, institution, or agency, WRF was developed in the U.S. through a partnership of both research and operational (i.e., official weather forecasting) groups. The initial development began in 1997, and the partners have been NCAR, the U.S. National Centers for Environmental Prediction (NCEP), the U.S. Air Force Weather Agency, the U.S. Navy’s Naval Research Laboratory, the NOAA’s Earth System Research Laboratory, the Federal Aviation Administration (FAA), and Oklahoma University. The goal was to create an NWP tool for use by both the operational and research meteorological communities. A key motivation was having a vehicle that, with relative ease and rapidity, could make the latest in research advances available to public forecasting.

The WRF modeling system features a software framework that is modular, plugin-compatible, and allows portability to a wide range of computer architectures. It runs on hardware from laptops, to desktop workstations, to PC Linux clusters, to high-performance supercomputers. WRF is parallelized and is efficient in massively parallel, distributed-memory environments. The software framework permits ease of coupling with other earth system numerical models (e.g., ocean circulation codes or air chemistry modules). WRF also provides sophisticated data assimilation— the incorporation of observed meteorological information from satellites and other observing systems

WRF is currently being used for official forecasting in the U.S. by NCEP, which provides NWP model guidance for the forecasters of the National Weather Service. On the research side, WRF’s applications range from study of atmospheric processes and weather from the tropics to the poles. Targets of special interest for WRF so far have been severe thunderstorms and powerfully damaging hurricanes, given their enormous societal impacts in the U.S. For the past three hurricane seasons, for example, WRF has been run at NCAR in real-time to offer high-resolution (i.e., detailed) forecasts of storms, which have threatened landfall. Figure 6 offers an example of how well WRF can depict one of these monsters. Successes such as this are demonstrating that WRF is fulfilling its promise as the pre-eminent next-generation numerical weather prediction model.