Forecasting the speed and longevity of severe mesoscale convective systems

This presentation will discuss some challenges of forecasting severe mesoscale convective systems (MCSs) from the perspective of the Storm Prediction Center and present some new ideas on forecasting MCS speed and longevity. Recent advances in numerical weather prediction models and computing power have allowed for explicit real-time prediction of MCSs over the past few years, some of which have supported field programs and collaborative experiments. While these numerical forecasts of MCSs are promising, the utility of these forecasts and how to best use the capabilities of the high-resolution models in support of operations is unclear. Therefore, refining our knowledge of the interactions of MCSs with their environment remains central to advancing our current ability to forecast MCSs. Predicting MCS speed in this manner is challenging because it requires knowledge of how the environment and system interact to affect the advection and propagation of the system itself. We will illustrate this challenge and discuss some forecast tools that have been developed in recent years to combat this forecast problem. Predicting MCS longevity is fraught with challenges such as understanding how deep convection is sustained through system/environment interactions, how pre-existing mesoscale features influence the system, and how the disturbances generated by the system itself can alter the system structure and longevity. Along with a discussion of these above topics, we will present some newly-developed ideas on MCS/environment interactions and how they affect system longevity and illustrate the observational support for these ideas. Some forecast tools that have been developed in support of the 2005 SPC Summer Program will be discussed. Finally, we will discuss how tools of this type can complement the forecasting of MCSs with high-resolution numerical prediction models.