* WHAT...For the High Surf Advisory, large breaking waves of 6 to 17 feet possible in the surf zone. For the Coastal Flood Watch, up to one foot of inundation above ground level possible in low-lying areas near shorelines and tidal waterways (3.7 to 12.9 feet Mean Lower Low Water). * WHERE...Eastern Essex MA, Suffolk MA, Eastern Norfolk MA, Eastern Plymouth MA, Barnstable MA, Dukes MA and Nantucket MA Counties. * WHEN...For the High Surf Advisory, from 5 AM Friday to 8 PM EDT Sunday. For the Coastal Flood Watch, from Friday afternoon through Saturday afternoon. * IMPACTS...Numerous roads may be closed. Low lying property including homes, businesses, and some critical infrastructure may be inundated. Some shoreline erosion may occur. Dangerous swimming and surfing conditions and localized beach erosion. * ADDITIONAL DETAILS...The exact timing for an approaching coastal low pressure remains uncertain. That will become important for peak surge around the times of high tides. Multiple tide cycles will be impacted, which combined with strong onshore flow may result in tides not lowering as well. Beach erosion will also be a concern, mainly for east-facing beaches. If travel is required, allow extra time as some roads may be closed. Do not drive around barricades or through water of unknown depth. Take the necessary actions to protect flood-prone property. Inexperienced swimmers should remain out of the water due to dangerous surf conditions.