A major transition in our ability to evaluate transient Global Climate Model (GCM) simulations and Numerical Weather Prediction (NWP) models is occurring. Real-time and retrospective numerical weather prediction analysis, model runs, climate simulations and assessments are proliferating from a handful of national centers to dozens of groups across the world. The growth of model development and evaluation is now possible due to the availability of multiprocessor workstations; analysis and forecast grids from various institutions; high temporal resolution forcing data from historical and future climate scenarios; assessment and model inter-comparison projects; and the emergence of new web-based distributed data services. The coordination of climate data infrastructure and management must extend beyond traditional organizational boundaries. It is clear that it is no longer sufficient for any one national center to develop its data services alone.

The primary U.S. National responsibility for the archive and service of weather and climate data rests with the National Climatic Data Center (NCDC). However, as supercomputers increase the temporal and spatial resolution of both NWP and GCM models, the volume and varied formats of data presented for archive at NCDC, using current communications technologies and data management techniques is limiting the scientific access of these data. To address this ever expanding need for climate and NWP information, NCDC along with the National Center's for Environmental Prediction (NCEP) have initiated the NOAA Operational Model Archive and Distribution System (NOMADS). NOMADS is a collaboration between the Center for Ocean-Land-Atmosphere studies (COLA); the Geophysical Fluid Dynamics Laboratory (GFDL); the George Mason University (GMU); the National Center for Atmospheric Research (NCAR); the NCDC; NCEP; the Pacific Marine Environmental Laboratory (PMEL); Unidata, the University of Washington, and others.

The objective of the NOMADS is to preserve and provide retrospective access to GCM's and reference quality long-term observational and high volume three dimensional data, NCEP NWP models and re-start and re-analysis information, as well as other NCDC available products and data. This paper describes this highly collaborative effort and provides a time-line for an estimated user access capability.