''We've had so much snow and the cold to preserve it,'' Vazzano said. ''We had storm after storm after storm.'' At times the snow was so plentiful it was problematic. The blizzard in late January triggered travel warnings and skiers in the Boston area were shoveling rather than skiing. It was followed closely by four successive weekends of winter storms. Vazzano said a cold spell in February helped preserve the snow but discouraged some skiers. ''When you can't get out of your driveway you can't get to the mountain,'