http://climateknowledge.org/figures/Rood_Climate_Change_AOSS480_Documents/Scott_Impacts_Lakes_Regional_Climate_JGreatLakesRes_1996.pdf

Impacts of the Great Lakes on Regional Climate Conditions

Characteristics of lake-effect snowstorms associated with the Great Salt Lake are described. Using WSR-88D radar imagery, 16 well-defined and 18 marginal lake-effect events were identified from September 1994 through May 1998 (excluding June–August), with the former used for more detailed analysis. Precipitation during the well-defined events was frequently characterized by the irregular development of radar echoes over and downstream of the Great Salt Lake. The most commonly observed precipitation structures were solitary wind-parallel bands that developed along or near the major axis of the GSL and broad-area precipitation shields with embedded convective elements that formed near the southern shoreline. Regional-scale composite analyses and rawinsonde-derived statistics showed that the lake-effect events occurred in post frontal westerly to northerly 700-hPa flow following the passage of an upper-level trough and associated low-level cold front. The lake-effect environment was characterized by...

Climatology of Lake-Effect Snowstorms of the Great Salt Lake

The forcing of mesoscale systems by horizontal gradients of surface heating is conceptually one of the most straightforward physical processes in the atmosphere. Therefore, it is surprising that thermally forced mesoscale systems are not exploited more by weather forecasters to provide improved predictions of local weather.

Mesoscale Circulations Forced by Differential Terrain Heating

Large spatial and temporal variations were observed in the location of the upwind cloud edge over Lake Michigan during five westerly wind lake-effect events in November 1995 through January 1996 This study examines the impacts of variations of Lake Michigan surface water temperatures (and corresponding surface fluxes) and upwind static stability on the location of the upwind edge of lake-effect clouds, which develop as cold air crosses the lake during the winter Data used in this study were collected during the 1995/96 National Weather Service Lake-Effect Snow study Spatial variations in the location of the upwind lake-effect cloud edge are shown to be related to spatial variations in surface heat and moisture fluxes between the lake surface and overlying air Surface fluxes are influenced by both the distribution of lake surface water temperatures and variations of surface wind speed, air temperature, and relative humidity Temporal variations of heat and moisture fluxes from the lake surface

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Observations of Widespread Lake-Effect Cloudiness: Influences of Lake Surface Temperature and Upwind Conditions

An array of 35 idealized mesoscale model simulations was used to examine environmental and surface forcing factors controlling the meso-β-scale circulation structure resulting from cold flow over an isolated axisymmetric body of water at the midlatitudes. Wind speed, lake–air temperature difference, ambient atmospheric stability, and fetch distance were varied across previously observed ranges. Simulated meso-β-scale lake-effect circulations occurred within three basic regimes (e.g., vortices, shoreline bands, widespread coverage), similar to observed morphological regimes. The current study found that the morphological regimes of lake-effect circulations can be predicted using the ratio of wind speed to maximum fetch distance (U/L). Lake-effect environmental conditions producing low values of U/L (i.e., approximately < 0.02 m s−1 km−1) resulted in a mesoscale vortex circulation. Conditions leading to U/L values between about 0.02 and 0.09 m s−1 km−1 resulted in the development of a shoreline ban...

Idealized Model Simulations Examining the Mesoscale Structure of Winter Lake-Effect Circulations

Radar and aircraft data are presented, in the form of case studies, for three shoreline-parallel snow bands that occurred over Lake Michigan. In all three cases a winter land breeze from one or both shores is shown to have an important role in organizing the low-level convergence and convective motions. These cases are compared with earlier studies of lake-effect snow bands on Lakes Erie and Ontario.

Richard E. Passarelli

Papers

The Role of the Winter Land Breeze in the Formation of Great Lake Snow Storms