Untangling the Effects of Latent Heat Release on an Extratropical Cyclone Using Potential Vorticity Analysis
To this end, we have chosen to perform a case study of an extratropical cyclone off the East Coast of the United States from November 21-26, 2006. Stationary for approximately 3 days, the storm was characterized by a continual warm conveyor belt airflow that stretched from the tropics to the Canadian Maritime provinces. Given the persistent condensation and subsequent latent heat release of the tropical air as it was drawn northward, this storm is an optimal case to isolate the effects of latent heat release on cyclone and frontal structure. To deconvolve these effects, we simulate this case with the Weather Research and Forecasting (WRF) model run at a cloud system resolving horizontal grid spacing of 4 km. We run 2 separate instances of the model: the first under a full-physics condition, with latent heat release included, and the second with the effect of latent heat release removed From our synoptic analysis, we find that the latent heat release has not necessarily served to enhance the storm strength, an unexpected result. Therefore, we adopt a potential vorticity perspective in our further analysis of the storm, deconvolving the influence of latent heat release from the influence of dynamics on the evolution of the case storm. These results can help us to anticipate possible changes in extratropical storm dynamics that may occur in a warming climate.