Thank you for your comment!  The term "statistical-dynamical model" can have slightly different meanings, depending on the context, but the main concept is the same.  The main idea is that for these hybrid models, we rely on the mathematical equations within a dynamical model to solve one part of the problem, usually the "bigger picture" part, while we also use statistical relationships from the historical record to connect the output from the dynamical model to the problem of interest.  This approach may be advantageous for computational efficiency or for problems in which the dynamical model does well for one part of the problem (e.g., the large-scale environment associated with high-impact weather) but not the main output of interest (e.g., the smaller scale high-impact weather). Some good examples of this type of model are the SHIP and DSHP models that the National Hurricane Center use to forecast tropical cyclone intensity (http://www.nhc.noaa.gov/modelsummary.shtml).