Hurricanes in Virginia

Hurricane Isabel
Hurricane Isabel, 2003 (Source: NOAA)

Hurricane disaster planning in Hampton Roads is focused on evacuating people if a Class 3 storm hits. In 2014, the emergency management professionals felt confident enough about predicting the path of strong storms to revise the evacuation plans. Old plans were based on closing gates along I-64, reversing the eastbound lanes so everyone in the region could flee inland to Richmond.

New plans involve defining specific evacuation zones for evacuation alerts, so fewer people will be asked to leave and congestion will be more manageable. The first areas to be evacuated will be low-lying areas subject to flooding by storm surges, and the governor will initiate the process for issuing warning to evacuate starting 72 hours (rather than 48 hours) before a storm's predicted arrival in Hampton Roads.1

Virginia rarely sees hurricanes stronger than Class 2, because storms moving north encounter cooler water and wind intensity drops. The wind offers some danger in Virginia, but flooding from the storm surge that accompanies a hurricane is the greatest danger on the coastline. In 1667 the water level in the Chesapeake Bay rose 12 feet, and in 1749 it rose 15 feet.2

There were "Great September Gusts" in 1667, 1769, 1775 (The "Independence Hurricane"), and 1821. The storm that passed over Mount Vernon on July 23, 1788 is called "George Washington’s Hurricane."

Hurricanes strike the Blue Ridge as well as the coastline. In 1967, Hurricane Camille entered the United States along the Gulf Coast, then moned inland until it paused at Nelson County. At least 27 inches of rain fell in six hours at Massies Mill, though the National Weather Service collected unverified information that 31 inches fell at some locations. Soil on mountainsides became saturated, triggering landslides and debris flows that left scars for decades. 113 people died in Virginia from the landslides and floods.3

Superstorm Sandy, October 2012
Source: MSNBC

Massive rainfall from a storm can overwhelm the stormwater management systems in urbanized areas, as Hurricane Floyd demonstrated in 1999 when it swamped the city of Franklin and tropical storm Gaston did to Richmond's Shockoe Valley in 2004. In 2003, winds from Hurricane Isabel wrecked utility systems throughout the Coastal Plain of Virginia, leaving some people without electricity for two weeks. In 2011, Hurricane Irene blasted Hampton Roads, Richmond, and Northern Virginia east of I-95.

storm surge can be as much as 15 feet higher than high tide
storm surge can be as much as 15 feet higher than high tide
Source: Virginia Department of Emergency Management, Virginia Hurricane Evacuation Guide

If a hurricane brings a storm surge of 6-8 feet into the region, much of Virginia Beach and Norfolk will be underwater due to the storm surge, the rise in sea level associated with the lower barometric pressure in the eye of the hurricane. Tidewater officials track hurricanes as closely as the officials in Florida or North Carolina, where most hurricanes come ashore on the East Coast, but no hurricane came ashore directly in Virginia in the 1900's.9

But inevitably, one is headed into the Chesapeake Bay. To prepare for evacuation, the state has designated hurricane evacuation routes for getting people out of the Hampton Roads area. The evacuation plan requires reversing eastbound I-64 to double the number of escape lanes headed west; there are gates on all interchanges between the high ground east of Williamsburg (I-295) and Hampton.

The Virginia Institute of Marine Sciences (VIMS) has even considered building a 24-mile long barrier at the mouth of the Chesapeake Bay, parallel to the bridge-tunnel, to block hurricane-caused storm surges. First step is to create computer models to assess potential designs and environmental impacts. The academic exercise requires making no decisions; the tough choices regarding costs vs. benefits (and how to ensure US Navy warships would never be trapped inside Hampton Roads) come later.4

sea level rise predictions
sea level rise predictions
Source: US Fish and Wildlife Service, Vanishing Lands - Sea Level, Society, and Chesapeake Bay (Figure 10)

Hurricane Isabel

Links

in 1969, Hurricane Camille dropped at least 27
in 1969, Hurricane Camille dropped at least 27" of rain overnight in Nelson County Source: National Oceanic and Atmospheric Administration (NOAA), Hurricane Camille - August 16-21, 1969

References

1. "Va. to move up hurricane evacuation timeline," The Virginian-Pilot, September 4, 2014, http://hamptonroads.com/2014/09/va-move-hurricane-evacuation-timeline (last checked September 7, 2014)
2. "The Hurricane History of Coastal Virginia," Virginia Department of Emergency Management Web site, http://www.vdem.state.va.us/library/hurhist.cfm, October 3, 2001
3. "Remembering Hurricane Camille 45 years later," Lynchburg News & Advance, August 19, 2014, http://www.newsadvance.com/news/local/remembering-hurricane-camille-years-later/article_eb722834-280f-11e4-8774-0017a43b2370.html (last checked August 23, 2014)
4. "Study investigates Chesapeake Bay storm-surge wall," The Virginian-Pilot, July 17, 2014, http://hamptonroads.com/2014/07/study-investigates-chesapeake-bay-stormsurge-wall (last checked September 7, 2014)

Station 42040 - MOBILE SOUTH 64 nm South of Dauphin Island, AL as of 1050 GMT on 09/17/2004
how wind and air pressure fluctuate as a hurricane passes over -
Hurricane Ivan off the coast of Alabama, September 2004
(Source: NOAA National Buoy Data Center)


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