Whether it is current customers or prospective ones that have been impacted by a flood, you only want to identify and communicate with those that HAVE been impacted.
Current customer data may be intersected with FEMA Flood Zone Data to identify those current customers that are likely to be impacted by an imminent threat--or may already have been.
Prospect data may be mined by intersecting Consumer or Business Information with the flood data to identify those that may need your services.