Numerical Weather Prediction (NWP) models are available in real time through a number of different channels. However, historical model input and output, which are needed for research, model improvement, publications, training, and collaboration, is more difficult to obtain. Local piecemeal approaches at government laboratories, data centers, and universities fall short of filling the need for access to retrospective models and associated data. Even with increases in available bandwidth and technological advances in distribution and access systems, access to retrospective binary models has been very limited. In fact, until now a U.S. National digital archive of operational weather models has simply not existed.

This paper describes the availability of a new historical model archive at the National Climatic Data Center. Through a collaborative project called the NOAA Operational Model Archive and Distribution System, both real-time and retrospective NWP initialization and restart files, NWP output, and General Circulation Models are now available for long-term access. This paper discusses the use of this system and how the archive will promote improvements to operational models by providing a feedback mechanism from the research to the operational communities. For further information visit the following web site: http://www.ncdc.noaa.gov/oa/climate/nomads/nomads.html.