Monday, October 5, 2015

Tidal Onslaught Brings Flooding

Tidal Onslaught Brings Flooding to 7 States, Highest Tide Since Hurricane Hugo in Charleston, South Carolina

    A days-long onslaught of tidal flooding, high surf and beach erosion along the Atlantic coast of the United States will persist through early this week. Strong onshore winds have already brought coastal flooding to oceanfront communities in at least seven East Coast states.Where these winds are blowing onshore, they're piling ocean water into the coastline, resulting in coastal flooding. Those same winds are also whipping up high surf on top of the high water, causing waves to break on sections of beach not typically affected by waves or tides during quiet weather.
    Adding to the high water, swells from Hurricane Joaquin are propagating to parts of the East Coast. Joaquin, itself, will also indirectly chip in to help maintain the stubborn onshore flow as it moves north and northeast in the western Atlantic Ocean.According to the warning bulletins, moderate to major coastal flooding may occur with the Monday evening high tide along the coast of the Delmarva Peninsula and the Virginia Tidewater. This includes the Hampton Roads metropolitan area encompassing Norfolk, Virginia Beach, Portsmouth, Newport News, and other nearby cities in southeastern Virginia.The large breakers and strong rip currents affecting the Atlantic coast now and for the next several days will be exceptionally dangerous for anyone caught in them.

    The setup for this coastal mess is a case of persistence and a blocked atmosphere. Strong surface high pressure is anchored over eastern Canada, as the tangled web of non-tropical surface low pressure near the Southeast coast and Hurricane Joaquin dominate farther south. Strong winds are one major factor in generating large ocean waves. Another is the distance that winds of a similar direction travel over water, known as the "fetch."High pressure aloft over the north Atlantic Ocean, and a reinforcement of high pressure aloft that will push in from eastern Canada, is blocking the normal west-to-east progression of weather systems, forcing low pressure aloft to simply sit and spin, if you will, over the southeastern U.S.

Current Coastal, Offshore Sustained Winds and Gusts

Surface setup for coastal flooding/beach erosion event. Generally higher surface pressure is shaded in blue, lower pressure in red. Position of Hurricane Joaquin is a model forecast for this past weekend, and does not constitute an official forecast position by either the National Hurricane Center or The Weather Channel.

Coastal Flood Alerts

Original Article: http://www.wunderground.com/news/east-coast-coastal-flooding-beach-erosion-high-surf-october-2015

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