Lake effect snow, which can be a type of snowsquall, is produced in the winter when cold winds move across long expanses of warmer lake water, picking up water vapor which freezes and is deposited on the lee shores.
This effect is enhanced when the moving air mass is uplifted by the orographic effect of higher elevations on the downwind shores.
This uplifting can produce narrow, but very intense bands of precipitation, which deposit at a rate of many inches of snow per hour.
The areas affected by lake effect snow are called snowbelts.
If the air temperature is not low enough to keep the precipitation frozen, it falls as lake effect rain.
In order for lake effect rain or snow to form the temperature difference between the water temperature between the surface and 850 mb should be at least 13 degrees Celsius.
Lake effect of extremely cold air over still warm water in early winter can produce thundersnow, snow showers accompanied by lightning and thunder.