Oh sheesh! Since I liek you I went to NOAA and plucked this plum for you.
Meteorological Variables
Temperature Difference Between Lake Surface and Overlaying Air: The temperature difference between the lake surface and overlying air promotes "convective instability " that provides the basic energy source for lake effect snow. Ideally, the ambient air temperature should be 15 C to 25 C cooler than the surface of the lake, and the dew point differential between the 850 mb level and the surface must be at least 13 C. In general, the greater the temperature difference between the cold air and the warm water, the heavier the snow showers will be. If the temperature contrast is great enough, the rising air will have enough buoyancy to form thundersnow (i.e., thunderstorms characterized by snow (as opposed to rainfall).
Wind Speed: Sufficient wind speed is necessary to advect arctic air over the lake, and transport sufficient amounts of warm, moist air to the shore. Increased wind speed also increases turbulent fluxes, which enhances the vertical mixing required for lake effect snows. A minimum wind speed of 5 meters/second is generally required for significant lake effect snow formation over land (otherwise, the snow that forms will fall over the lake or along the immediate shoreline). On the other hand, if the wind speed is too strong, residence time over the lake is reduced and the air passes over the lake too quickly to pick up sufficient heat and moisture needed for lake effect snow.
Wind Direction (and Duration): Local surface wind direction determines where lake effect snow will fall, with the leeward or downwind portion of the lakeshore receiving the most lake effect snow. Wind direction also helps determine the fetch (see definition below).
Stability: Stability affects the depth through which mixing and convection will occur. Deeper mixing allows deeper, more intense convection that intensifies lake effect snow. Stability also plays a role in determining cloud band structure.
Latent Heating: Latent heat release from condensation (cloud formation) provides an important additional energy source for convective instability and subsequent lake effect snows (as it is a significant heat input to the mixed layer).
Relative Humidity: The relative humidity of the upstream air determines the amount of moisture required to saturate it. In general, the dry arctic air masses that generate lake effect snow requires longer residence times over water to saturate.