Boundary layer dynamics and eddy fluxes in horizontal roll convection during

Lake-effect snow storms impact the lives, industry and property of areas that lie in their path. Thus, accurate forecasting of the intensity and placement of these systems is important to those affected. In order to improve forecasts of lake-effect snow storms it is important to increase our understanding of the processes involved in lake-effect snowstorms, including atmospheric boundary layer (BL) dynamics and the eddy-flux processes associated with these dynamics. Here, the focus will be on lake-effect snow caused by horizontal roll vortices and non-roll BL convection formed during cold air outbreaks (CAO) over Lake Michigan in January 2004. Aircraft and 3mm Doppler radar measurements taken by the Wyoming King Air research aircraft will be used to: 1) study the characteristics of horizontal roll dynamics in lake-effect snow storms over Lake Michigan using single and dual Doppler analysis along with other aircraft data and subsequent Fourier and Wavelet Spectral analysis and 2) identify and characterize the role horizontal roll convection plays in the placement and magnitude of eddy fluxes of momentum, sensible and latent heat of these systems. To accomplish these research goals two cases will be evaluated: the first on January 22, 2004, where roll structure was evident in both ground based radar and aircraft data and the second on January 31, 2004, where roll structure was not prevalent, but convection was visible.