Whither the study of midlatitude fronts and cyclones?

To anyone who is familiar with the progress of meteorological research over the last three decades or so, it is apparent that the 1980s and 1990s can be viewed as a “golden era” of sorts for the study of midlatitude fronts and cyclones. Spurred on by rapid advances in observing system technologies, computer power, and numerical model sophistication, and by a number of key papers that provided dynamical insights into the workings of fronts and cyclones, an eager and innovative research community improved our understanding of midlatitude fronts and cyclones by leaps and bounds during that period. Much was learned about these phenomena in terms of their evolving structures, dynamical behavior, precipitation processes, etc. It is also clear that many of the innovators who contributed to that “golden era” have, in the last decade or so, shifted the emphasis of their research to new important frontiers, including data assimilation, predictability, and forecast verification. One might interpret this evolution as a sign that midlatitude fronts and cyclones are largely a “solved problem”. This talk attempts to demonstrate that such is not the case, by providing an overview of recent research areas and findings, and a look toward future directions. In the realm of fronts, there is renewed interest in the importance of air mass contrasts on the behavior of fronts, an idea has been neglected for some time within the realm of theoretical and idealized modeling studies of fronts. There also continues to be further advancements in our understanding of the fine-scale structure and behavior of fronts, as revealed by detailed observational analyses and modeling studies from field projects such as IHOP. A number of questions regarding the interactions of fronts and other boundaries with each other and with surface inhomogeneities remain to be answered. In the realm of midlatitude cyclones, the study of cyclone climatology has seen somewhat of a resurgence, spurred on by the availability of high-quality global reanalysis data sets, and the need to understand possible changes in cyclone behavior in a changing global climate. Innovative techniques have been developed to automatically identify cyclones and their attributes in the gridded data. These techniques are used to produce climatologies of cyclone tracks, growth and decay, and to composite satellite and radar-derived precipitation fields relative to the cyclone structure. Important questions about physical processes within cyclones also continue to motivate communal research efforts, such as the mechanisms for development of damaging, high-wind “sting jets” in the southwest quadrants of cyclones, the role of surface friction in the potential-vorticity dynamics of cyclones, and the relationship between cyclones and narrow “atmospheric rivers” that are responsible for much of the poleward moisture flux in midlatitudes. Finally, there is much emphasis in recent research (and upcoming field programs) on the behavior of cyclones in terms of groups or “wave packets” rather than as individual entities. Such studies are attempting to address the questions of how such packets are triggered, what are the properties of the wave guides on which they propagate, and what physical processes within cyclones might help to sustain or modify the wave packet.