The Collaborative International Dictionary of English v.0.48:

Snowstorm \Snow"storm`\, n.
   A storm with falling snow.
   [1913 Webster]

WordNet (r) 3.0 (2006):

snowstorm
    n 1: a storm with widespread snowfall accompanied by strong
         winds [syn: blizzard, snowstorm]

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "snowstorm":
   avalanche, black spot, blizzard, bloom, blooping, crystal, cyclone,
   definition, dirty weather, driven snow, flake, flare, flurry,
   foul weather, fringe area, ghost, granular snow, granulation, grid,
   hard shadow, hurricane, igloo, image, line squall, mantle of snow,
   mogul, multiple image, noise, picture, picture noise,
   picture shifts, rain, rainstorm, rolling, rough weather,
   scanning pattern, scintillation, shading, slosh, slush, snow,
   snow banner, snow bed, snow blanket, snow blast, snow fence,
   snow flurry, snow roller, snow slush, snow squall, snow wreath,
   snow-crystal, snowball, snowbank, snowbridge, snowcap, snowdrift,
   snowfall, snowfield, snowflake, snowland, snowman, snowscape,
   snowshed, snowslide, snowslip, squall, storm, stormy weather,
   tempest, tempestuous rage, thunderstorm, tornado, typhoon,
   wet snow, windstorm