Virginia coast could face historic storm surge

Virginia coast could face historic storm surge:
Storm Introduction:
A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea level. Low pressure at the center of a weather system also has a small secondary effect, as can the bathymetry of the body of water. It is this combined effect of low pressure and persistent wind over a shallow water body which is the most common cause of storm surge flooding problems. The term "storm surge" in casual (non-scientific) use is storm tide.Along the coast, storm surge is often the greatest threat to life and property from a hurricane. In the past, large death tolls have resulted from the rise of the ocean associated with many of the major hurricanes that have made landfall. Hurricane Katrina (2005) is a prime example of the damage and devastation that can be caused by surge. At least 1500 persons lost their lives during Katrina and many of those deaths occurred directly, or indirectly, as a result of storm surge.
Virginia coast:
Storm surge estimates are rising, which means worse flooding for parts of Norfolk and Portsmouth as Hurricane Irene bears down on Virginia, according to Gov. Bob McDonnell.We are still right in the line of fire,” McDonnell said in an interview with MSNBC. “We've got two or four hours now we're expecting the worst part of the storm, the highest winds.The storm surge estimates have gone up in the last hour to now 5 to 7 feet, which means that some of the areas of Norfolk and Portsmouth will actually have 9 feet above mean low water mark, so it's going to be significant flooding in those areas.“We're still expecting as much as 12 inches of rain and maybe as high as 15 in some areas.”McDonnell said Virginia is up to about 650,000 customers out of power “which means about 1.5 million people, so it's a significant event (and) we expect more of that.”Virginians “have largely heeded the mandatory evacuation orders that we gave earlier,” he said.And they're staying off the roads, which is just great.