Termination by abandonment. Any nonconforming sign, the use
of which is discontinued for a period of 90 days, regardless of any
intent to resume or to not abandon such use, shall be deemed to be
abandoned and shall not thereafter be reestablished. Any period of
such discontinuance caused by government actions, strikes, material
shortages or forces of nature, and without any contributing fault
by the nonconforming user, shall not be considered in calculating
the length of discontinuance for purposes of this subsection.