Shovel the snow off the grass as it starts melting or spread it out around the yard so it melts faster. The sooner the lawn gets regular sunlight and dries out from the excess moisture, the better the odds it will survive a snow mold infection.
Rake the grass so it stands upright. Grass gets flattened by the weight of the snow and foot traffic, which makes it susceptible to snow mold. Raking out the affected areas undoes some of this damage and helps the lawn to repair itself.
Mow the lawn in the fall, before snow falls, to further prevent the threat of snow mold. The longer the grass when the snow starts to build, the better the environment for snow mold growth.
Apply a fungicide to the lawn in extreme cases if the snow mold isn't going away on its own. This is rarely necessary but will help prevent further lawn damage if the mold is still spreading. Preventative fungicide application in the late fall is only recommended if your lawn has a history of snow mold problems.