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.

Storm Surge

New York City storm surge:
In an unprecedented move, New York City is evacuating nearly 400,000 residents of low-lying sections of Manhattan, Brooklyn, and Queens. Just as unprecedented, the city's airports and subways are being shut down, and Con Ed is warning that if it has to cut electricity to Wall Street, it could take three days to restore it

Storm Details:
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; that is, it refers to the rise of water associated with the storm, plus tide, wave run-up, and freshwater flooding. When referencing storm surge height, it is important to clarify the usage, as well as the reference point. National Hurricane Center tropical cyclone reports reference storm surge as water height above predicted astronomical tide level, and storm tide as water height above NGVD-29. Most casualties during a tropical cyclone occur during the storm surge.
 

 How high will the flood waters go?
The National Hurricane Center warned that hurricane Irene was still expected to arrive in New York Sunday night at or near hurricane strength.The big concern: Storm surge.The Miami-based National Hurricane Center has forecast a storm surge of up to 8 feet for Long Island and metropolitan New York when Irene passes, Reuters reports.Storm surge is caused primarily by strong winds pushing on the surface of the water, creating a higher than normal tide. Other factors contributing to storm surge can be large amounts of rain, and in this case, a full moon on Sunday.Higher than normal astronomical tides are occurring this weekend," said Daniel Brown, a meteorologist for NOAA's National Hurricane Center. "Coastal and river flooding will be highest in areas where the peak surge occurs around the time of high tide."A storm surge model developed by MIT, shows that areas around Manhattan, including lower Manhattan, could show a surge of four feet on top of the high tide.Another model by The Stony Brook Storm Surge Research Group at the State University of New York, offers an interactive map that's updated every 12 hours. It indicates that the peak surge for The Battery is at 5:15 am Sunday. If you click on the buoys on the map around New York, you can see the surge charted in specific areas over the next 12 hours.The Stony Brook site advises that this is a research model still under development and shouldn't be use for evacuation decisions.But clearly NYC officials are taking the storm surge threat seriously.Consolidated Edison said it wouldn't shut down the city's electricity pre-emptively, but could cut power early Sunday in low-lying parts of Manhattan, including to 6,000 homes or businesses south of the Brooklyn Bridge. The area includes New York's Financial District, according to Reuters.Con Ed officials say it could take three days to restore power in lower Manhattan, if power is shut off, reports The New York Daily News.