Nonconforming open storage yards, outdoor displays or junkyards in any residential district, PO, HB, CBD, WD or M District. Any nonconforming open storage yard or any outdoor display or storage of merchandise in connection with an auction establishment or store specializing in secondhand merchandise, in any residential district, PO, HB, CBD, WD or M District, which is nonconforming, either because not permitted in the district or because not located within a completely enclosed building, may be continued for one year after the effective date of this chapter, provided that after the expiration of that period such nonconforming use shall then be terminated. However, no such use will be required to terminate if within said period it shall be located within a completely enclosed building. Any nonconforming junkyard in any residential district, PO, HB, CBD, WD or M District may be continued for three years after the effective date of this chapter, provided that after the expiration of that period such nonconforming use shall then be terminated.