WordNet (r) 3.0 (2006):

storm cellar
    n 1: an underground shelter where you can go until a storm
         passes [syn: storm cellar, cyclone cellar, tornado
         cellar]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "storm cellar":
   abri, air-raid shelter, basement, bomb shelter, bombproof, bunker,
   cave, cellar, cellarage, coal bin, concealment, cover, covert,
   coverture, cyclone cellar, dugout, earth, fallout shelter, foxhole,
   funk hole, hold, hole, potato cellar, safety zone, shelter,
   storm cave, subbasement, trench, wine cellar