A numerical investigation of wind speed effects on lake-effect storms

Abstract

Observations of lake-effect storms that occur over the Great Lakes region during late autumn and winter indicate a high sensitivity to ambient wind speed and direction. In this paper, a two-dimensional version of the Penn State University/National Center for Atmospheric Research (PSU/NCAR) model is used to investigate the wind speed effects on lake-effect snowstorms that occur over the Great Lakes region.Theoretical initial conditions for stability, relative humidity, wind velocity, and lake/land temperature distribution are specified. Nine different experiments are performed using wind speeds ofU=0, 2, 4,..., 16 m s−1. The perturbation wind, temperature, and moisture fields for each experiment after 36 h of simulation are compared.It is determined that moderate (4–6 m s−1) wind speeds result in maximum precipitation (snowfall) on the lee shore of the model lake. Weak wind speeds (0≤U<4 m s−1) yield significantly higher snowfall amounts over the lake along with a spatially concentrated and intense response. Strong wind speeds (6<U≤16 m s−1), yield very little, if any, significant snowfall, although significant increases in cloudiness, temperature, and perturbation wind speed occur hundreds of kilometers downwind from the lake.