* WHAT. For the Coastal Flood Advisory, up to one half foot of inundation above ground level in vulnerable areas near the waterfront and shoreline. For the High Rip Current Risk, dangerous rip currents expected. * WHERE. Southwest Suffolk, Southeast Suffolk and Southern Nassau Counties. * WHEN. For the Coastal Flood Advisory, until 11 PM EDT this evening. For the High Rip Current Risk, from Friday morning through Friday evening. * COASTAL FLOOD IMPACTS. Minor flooding in the most vulnerable locations near the waterfront and shoreline. Expect up to 1 1/2 feet of inundation above ground level in low lying, vulnerable areas. Some roads and low lying property including parking lots, parks, lawns and homes/businesses with basements near the waterfront will experience shallow flooding. * SHORELINE IMPACTS. Along the north shore of the south fork of Long Island, breaking waves of 1 to 3 feet may cause dune erosion and localized washovers, as well as enhance splashover and flooding onto shoreline roads and properties. Along the oceanfront, breaking waves of 4 to 6 feet on an east to west sweep will result in beach erosion and beach flooding during the times of high tide. Localized dune erosion is possible. * RIP CURRENT IMPACTS. Life-threatening rip currents are likely for all people entering the surf zone. Anyone visiting the beaches should stay out of the surf. Rip currents can sweep even the best swimmers away from shore into deeper water.