Storm surge can be the deadliest effect of a tropical storm. The National Hurricane Center is attempting to mitigate this risk by issuing storm surge watches and warnings. (NOAA)

With a major hurricane poised near the Texas coastline and expected to stall for several days, it's essentially a worst case-scenario for beachside communities in the path of Hurricane Harvey. While destructive winds and nearly unprecedented rainfall amounts will lash the Gulf Coast, a devastating storm surge will roar ashore Friday into Saturday, raising the sea as much as 12 feet above normally dry land.

Because Harvey is forecast to stall, storm surge inundation may persist for several days in the hardest-hit areas, flooding roads, homes and businesses, and making it difficult to return to them.

The National Weather Service has launched the first-ever issuance of their new product, the Storm Surge Warning. A rendition of what was previously the Coastal Flood Warning, this alert is reserved only for cases when "the danger of life-threatening inundation from rising water moving inland" will pose a serious threat to local residents.

(National Hurricane Center)

A storm surge is not a wave of water but, rather, the gradual rise of sea levels because of water blown by the storm and an upward tidal bulge resulting from the storm's exceptionally low pressure. All said, the ocean may tower 10 or more feet above normal, racking the coastline and sweeping away structures caught in harm's way.

The National Weather Service in Corpus Christi, Tex., is calling for "extreme storm surge flooding greater than 9 feet above ground" and advises that residents "aggressively prepare for catastrophic flooding impacts."

It should be noted that, because of wind direction, duration and local topography, the maximum levels of inundation at a location do not necessarily correspond to the intensity of the wind/rainfall. Instead, the most devastating impacts will be felt on the north side of the storm, particularly Aransas National Wildlife Refuge and Matagorda Bay toward Freeport and Lake Jackson. Communities on either side of this stretch will still experience moderate to major storm surge flooding.

Especially at risk will be Port Lavaca, Port O'Connor and Seadrift, which can anticipate a staggering rise of eight to 12 feet. Bayside, Refugio and Woodsboro are next in line for top-end inundation. This will be potentially deadly to anyone caught in the danger zone, so now is the time to prepare. This may mean abandoning property and simply fleeing as quickly as possible to a place of safety.

Sheltering from the wind is easy; hiding from water is impossible for those within 12 feet of sea level. Keep in mind that there is nothing to hold back the water from racing as much as a mile or more inland; to reiterate, a storm surge is not a series of waves that will recede but, instead, can be visualized as the ocean simply being 12 feet higher than it typically is. The vast majority of hurricane deaths occur because of flooding; now is not the time to be brave, because you don't want to become a statistic on the 11 o'clock news after the storm; get out. Poor decisions may cost you your life.

Elsewhere, Corpus Christi, Port Aransas and Robstown will see a 4-to-7-foot surge. Lesser amounts, on the order of a few feet, will be found toward Baffin Bay, Malaquite Beach and Kingsville. Toward Galveston and Houston, meanwhile, the official forecast calls for 5 to 8 feet; however, it could be 1 to 2 feet higher. This is because of the prolonged onshore winds and storm surge precluding excessive rainfall from draining into the ocean, resulting in exacerbated flooding issues around the time of high tides. This is problem known as compound flooding.

Past hurricanes in Texas, such as Ike in 2008, have wrought havoc with their storm surge flooding, and Harvey will be no exception.

Residents along the immediate shoreline should wrap up preparations.