About the NMME

The North American Multi-Model Ensemble (NMME) is a seasonal prediction system that combines forecasts from the leading North American climate models. It constitutes a multi-agency and multi-institutional research-to-operations (R2O) effort jointly led by the NOAA Climate Program Office (CPO) Modeling, Analysis, Predictions, and Projections (MAPP) program and the NOAA Climate Test Bed (CTB). The NMME’s increased ensemble size compared to NCEP’s operational Climate Forecast System (CFSv2) and its diversity of models contribute to superior seasonal forecast skill, on average, relative to other seasonal prediction systems. In addition, the NMME system enables more reliable estimates of prediction confidence, critical information for decision makers. NMME predictions and hindcasts provide a unique research platform for predictability and prediction research.

Prediction systems contributing to the operational NMME Phase II, version 1 system

Organizations Models
NOAA National Centers for Environmental Prediction CFSv2 (operational system)
NOAA Geophysical Fluid Dynamics Laboratory FLOR (research system)
NASA Global Modeling and Assimilation Office GEOS5 (research system)
Environment Canada CMC1-CanCM3 (operational system)
CMC2-CanCM4 (operational system)
National Center for Atmospheric Research CESM1 (research system)
CCSM4 operated by U. Miami/CIMAS (research system)

Path from research to operations

Development and Demonstration

The MAPP Program and the NOAA CTB program jointly organized workshops in February and April 2011 that first established the scope of the development of the NMME initiative (NMME Phase I), which was subsequently competitively funded as a one-year MAPP-CTB Project in FY 2011. The goal of NMME Phase I was to test and optimize the design of the NMME system for seasonal prediction, and to attempt to demonstrate that it could improve seasonal predictions compared to the then-current operational prediction systems on which the NMME was based. In concert with this project, the NWS CPC began to produce NMME predictions on a real-time operational schedule in September 2011.

Upon completing the development phase at the end of FY 2011, the NMME project entered a two-year demonstration phase (FY 2012 and 2013). In Phase II of the project, the NMME was competitively funded as a NOAA CTB research project with the joint support of NSF, DOE, and NASA. During its development, NMME Phase I and II data continued to serve as the basis for a variety of prediction and predictability research projects.

Transition to Operations

In September 2014, an expert panel reviewed the outcome of the NMME research project, as part of the NOAA CTB process, and determined that the system was ready for deployment into NWS operations based on the performance of the experimental NMME system relative to other available seasonal prediction systems. Following the review, NOAA decided to transition the NMME to operations and started the underpinning process while the NMME real-time predictions were incorporated as part of the NWS operational production suite.The transition process was formally completed in May 2016.

The transition of the NMME to operational mode serves the dual purpose of enhancing operational seasonal forecasts at NCEP and Environment Canada and enabling research on prediction and modeling based on NMME data. The operational NMME allows the operational centers involved to receive improved forecast data and the research centers to have their models tested in an operational environment, which will inform future model development. The publicly available NMME real-time and hindcast forecasts also enable research at the participating centers, as well as in the larger science community.

The individual prediction systems constituting the NMME are operated according to a common protocol, available here.

Ongoing Research

Since 2011, the MAPP program has funded many research projects to develop, evaluate and apply the NMME seasonal prediction system in support of NOAA's mission of societal resilience. In FY 2015, the MAPP program supported 12 new research projects to evaluate and develop new applications for the NMME. The projects use the NMME system to address important seasonal prediction issues, including the role of abrupt changes in the circulation of the stratosphere on seasonal prediction skill, the seasonal prediction of atmospheric rivers and tropical cyclones, and the development of experimental excessive heat outlooks for weeks 2–4.

A Special Issue in the journal Climate Dynamics is being prepared on the use of the NMME system database for research ranging from predictability studies, to multi-model prediction evaluation and diagnostics, to emerging applications of climate predictability for subseasonal to seasonal predictions. Please see this page for more information.


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Dr. Annarita Mariotti
MAPP Program Director, on detail to EOP/OSTP
P: 301-734-1237

Dr. Daniel Barrie
Acting MAPP Program Director
P: 301-734-1256

Courtney Byrd
MAPP Program Specialist
P: 301-734-1257

«August 2022»


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