In freezing conditions precipitation from stagnant low stratus in the form of snow grains is enhanced near concentrated sources of moisture. The area affected by snow grains is typically 4 km square and the amount of precipitation is usually small but leads to slippery conditions on frosty road surfaces. Winter road maintenance is needed for the affected roads and sidewalks. Normally the use of salt is sufficient. In extreme cases mechanical snow removal is needed. The very local occurrence of snow covered roads in generally stable weather conditions without precipitations is often surprising for road users as well as for road maintenance services. Thus the phenomenon increases the risk of accidents. Locally enhanced precipitation of snow grains occurs most frequently in the cold morning hours. With low stratus persisting all day it can also occur after dusk.