A number of frameworks, tools, and datasets (and underlying weather and climate parameters/hazards) are currently used by the Department of Defense (DoD) in forecasting weather at daily, weekly, monthly and intra-annual seasonal scales, and in developing projections of future climate at multi-decadal scales within the US (CONUS, AK, HI) and globally. The overall objective of this topic was to test and evaluate strategies, frameworks, tools, models, and datasets to bridge existing gaps in the Weather-to-Climate Continuum (W2CC) prediction and projection datasets. Of particular interest were proposals that supplement projection datasets that are currently used by the DoD for projection periods of approximately one to ten years. Specific project needs included: 

• Test and evaluate performance of available and actionable W2CC strategies, frameworks, tools, and datasets that the DoD should consider implementing in order to bridge existing W2CC gaps across relevant time scales (inter-annual and decadal). 
• Evaluate, assess, and develop strategies to specifically identify skills, uncertainties, and biases in weather and/or climate projections datasets at relevant time scales to bridge the W2CC. 
• Document all findings and conclusions in a report with clearly identified implementation advantages and disadvantages for the DoD to consider in bridging existing gaps in the W2CC. 

Addressing the objectives described above will facilitate the DoD’s implementation of the best available and actionable strategies, frameworks, tools, and datasets for forecasting and projecting future weather and climate across all relevant time scales to meet DoD needs for weather and climate change exposure assessments, climate adaptation, and resilience. 

The DoD uses a variety of frameworks, tools, and underlying datasets to provide weather forecasts and future climate change projections. These include historical climatology (including historical extreme events), hourly, daily, monthly and seasonal to sub-seasonal intra-annual weather/climate predictions as well as multi-decadal climate projections. A long-standing challenge for meteorology and climate science has been to develop techniques capable of producing predictions and simulations of the weather and climate across a range of timescales. If numerical weather prediction (days-ahead) and long-term climate change simulations (decades-ahead) can be considered as examples of initial condition and boundary condition problems, it is clear that much lies between these two extremes. 

Previous coordination between Military Department subject matter experts identified the one- to ten-year time horizon as needing both weather and climate change expertise to improve uncertainties. Here, weather prediction models start to lose the signature of the initial forcing, accompanied by increasing uncertainty, while climate change projection models do not reliably produce the near-term effects included in the climate pathways/scenarios. Ongoing research at these time scales includes the WMO Lead Centre for Annual-to-Decadal Climate Prediction and the Working Group on Sub-seasonal to Interdecadal Prediction (WGSIP). However, actionable downscaled products across those time scales remain scarce. 

There is thus a clear need to develop a strategy, frameworks, tools, and datasets, including quantification of any associated uncertainties, to bridge the W2CC gap in the inter-decadal time scale (1 to 10 years) to produce best available and actionable DoD weather forecasts and climate projections across all time scales. 

Kevin Hiers
Program Manager for Natural Hazards Adaptation
Environmental Security Technology Certification Program (ESTCP) 
4800 Mark Center Drive, Suite 16F16 
Alexandria, VA 22350-3605 
E-Mail: john.k.hiers.civ@mail.mil  and ellen.westfall@noblis.org