if a Class 3 hurricane pushed a storm surge into Chesapeake Bay at high tide, flooding in Hampton Roads would be massive
Source: Virginia Department of Emergency Management, Virginia Hurricane Evacuation Guide
Hurricanes affected Native Americans living near the Chesapeake Bay before colonization, but there are no records documenting storms or their impacts on people living in Powhatan's paramount chiefdom or other parts of what we now call Virginia.
There are records of major storms after permanent colonization started in 1607. A hurricane almost ended English settlement at Jamestown just two years after it began.
In 1609, the Third Supply fleet sailed from England and ran into a storm near Bermuda. The flagship Sea Venture with Sir Thomas Gates, who had been appointed by the Virginia Company to serve temporarily as governor in Jamestown, crashed onto the reef at Bermuda. All on the ship survived the wreck, but the Jamestown colonists experienced the Starving Time of 1609-10 under the inept leadership of George Percy while the new officials were marooned on an island in the Atlantic Ocean.
When Sir Thomas Gates finally reached Jamestown in 1610, after building two new ships on Bermuda, he quickly concluded the colony could not survive and ordered everyone to sail back to England. A storm that had started off the coast of northern Africa could have made Jamestown a ghost town. Only the timely arrival of Lord De La Warre, with additional supplies and colonists, kept the English colony going in Virginia.
the most-direct route from England to Virginia required tacking against westerly winds, so ships often sailed south to the Azores and then west across the Atlantic Ocean following the same track as hurricanes
Source: Atlas of the Historical Geography of the United States, Winds and Sailing Routes: Summer (Plate 1e, digitized by University of Richmond)
The 1609 hurricane which affected the colony occurred far at sea and south of Virginia. The most likely "worst case scenario" for a hurricane striking Virginia itself is for a Class 3 storm to make landfall at the mouth of the Chesapeake Bay.
Puerto Rico, Caribbean islands, Florida and Louisiana get struck by Class 5 hurricanes. South Carolina gets hit by Class 4 hurricanes, including Hurricane Hugo which devastated the state in 1989, while Virginia rarely experiences even Class 2 storms.
Virginia gets less-intense storms because of its position on the globe north of 36° 30' latitude. Hurricanes moving north of the Carolinas encounter cooler water. The wind intensity drops as the temperature of the ocean drops, so the category on the Saffir-Simpson Saffir-Simpson Hurricane Wind Scale is diminished. As the ocean warms over the next century, however, Class 3 hurricanes could become more common and a Category 6 might be needed on the existing scale.
Hurricane typically make landfall south of Virginia, so winds in Hampton Roads start from the northeast and then shift as the storm moves north. A report of a 1667 storm noted:1
On July 24, 1788, George Washington recorded the wind pattern from the hurricane that passed over Mount Vernon the previous day:2
The wind from hurricanes offers some danger in Virginia, but flooding from the storm surge is the greatest danger on the coastline. The 1667 hurricane may have brought the strongest winds to strike the Virginia coast in recorded history, but not the highest water levels.
The water level in the Chesapeake Bay apparently rose 12 feet in 1667, but in 1749 another storm created a 15-foot high storm surge. The floodwaters in that storm pushed enough sand out of the Chesapeake Bay to create the initial Willoughby Spit, which was enlarged to current dimensions by the "Great Coastal Hurricane of 1806."
Willoughby Spit was formed primarily by two hurricanes in 1749 and 1806
Source: US Army Corps of Engineers, Norfolk District Image Gallery
There was a significant hurricane in 1769, the "Independence Hurricane" in 1775, and "George Washington’s Hurricane" on July 23, 1788. Major storms in the 1800's include the Great Coastal Hurricane of 1806 and an 1821 hurricane whose eye passed directly over Norfolk.
An 1821 hurricane is known as the Great September Gust. It completely flooded Chincoteague Island, perhaps after triggering a landslide on the continental slope and causing a tsunami. No houses survived on the island; the oldest structures on Chincoteague today were built as replacement houses after the 1821 storm.
The eye of the "Great Tempest" of 1879 was 50 miles west of the city. That storm triggered a high tide eight feet higher than normal. An eight-foot high storm surge today would devastate downtown Norfolk and the US Navy's largest base.
Significant hurricanes in the 1900's include a 1903 storm that killed hundreds of small birds at Old Point Comfort, stripping their feathers while in flight and causing a deluge of carcasses falling out of the sky.
The eye of the August 23, 1933 Chesapeake-Potomac Hurricane also passed directly over Norfolk, resulting in one of the lowest barometric pressures (28.68") ever recorded in Virginia. The storm paralyzed Tidewater, after a surge of water as much as nine feet high moved up the Chesapeake Bay.
On the south bank of the James River opposite Jamestown, the pier for the Surry-Jamestown Ferry was destroyed. At Colonial Beach, the amusement park washed away. Three feet of water covered the Washington-Hoover airport at the current site of the Pentagon. North of Chincoteague, the storm cut through Assateague Island and created the Ocean City inlet.
The 1935 Labor Day Hurricane which devastated the Florida Keys moved north into Virginia. It was a much-diminished storm when it moved back into the Atlantic Ocean near the North Carolina/Virginia border, but still powerful enough to spawn a tornado in Portsmouth. Many other hurricanes that move into Virginia as tropical storms have also caused tornadoes, so wind damage remains a serious threat even as hurricanes are fading.
Hurricane Hazel in 1954 passed west of Reagan National Airport, bring 98mph wind gusts. Remnants of that hurricane demonstrated how storm impacts can occur across the state, and not just along the cast. In the Shenandoah Valley, 150,000-250,000 turkeys died when the storm knocked down poultry sheds. In 1955, Hurricane Diane brought 5-10" of rain to the slopes of the Blue Ridge, creating flash floods.3
On the evening of August 19-20, 1969, the residue of Hurricane Camille stalled over the Blue Ridge in Nelson County. The winds of the storm had slowed down and it was no longer classified as a hurricane, but the clouds were still of moisture. Air currents and topography kept Camille overnight in Nelson County. Multiple storm cells formed in the thunderstorm complex at essentially one place, and together they dropped as much as 30" of rain in just eight hours.
The water over-saturated the hillsides and liquified the soil, causing landslides that crashed into the valley of Davis Creek and other tributaries of the Tye and Rockfish rivers. At least 113 people died, and debris scars or "chutes" on the slopes are still visible today.
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
One effect of the storm is that emergency managers began to plan for the risks of hurricane damage that might occur far from the Atlantic Ocean. The winds and storm surge, the rise in sea level associated with the lower barometric pressure in the eye of the hurricane, is only one of the threats. Hurricanes can cause falling trees, landslides, loss of electricity and drinking water, and disruption of the transportation network within the Appalachian Plateau, the Valley and Ridge Province, the Blue Ridge, and the Piedmont as well as on the Coastal Plain.
Geologists and hydrologists also realized after Hurricane Camille that such major storms occur every 500-1,000 years in the watersheds of the Blue Ridge. Such massive rainstorms are rare events, but occur frequently enough to be a key factor in shaping the morphology of the Blue Ridge.
Topographic change is a process of "punctuated evolution" as well as gradual change. In just a minutes, big storms can transform the landscape more significantly than centuries of slow erosion. The 1969 storm and a 1995 flash flood in Madison County helped to reveal that much of the carving of stream valleys, and much of the lowering of Virginia's mountains, occurs in short bursts from major storms.4
Hurricane Agnes created massive flooding in 1972. Floodwaters flowing over the top of the two dams on the Occoquan River destroyed the Route 123 bridge at the Town of Occoquan, plus one of the Route 1 bridges downstream.
the Route 123 bridge destroyed in Hurricane Agnes, 1972
Source: Library of Virginia, Raging Occoquan River
the Route 1 bridge destroyed in Hurricane Agnes, 1972
Source: Library of Virginia, Repairs begin at Occoquan Bridge
In 1996, Hurricane Fran brought 16 inches of rain to Big Meadows. Shenandoah National Park was closed for two weeks.
In September, 1999, the remains of Hurricane Floyd dropped 15" or more of rain within 24 hours in Southeast Virginia. Runoff caused the Blackwater River to rise and inundate the Town of Zuni and the City of Franklin. From Florida to Virginia, an estimated 3,000,000 people tried to drive away from the storm. The traffic jam is legendary for emergency managers, and spurred planning in Virginia to avoid a repeat of that congestion if the governor orders an evacuation.5
extraordinary rainfall from Hurricane Floyd created flooding in Zuni and Franklin
Source: National Weather Service, Hurricane Floyd Storm Summary
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
Source: Virginia Department of Emergency Management, Virginia Hurricane Evacuation Guide
If a hurricane brings a storm surge of 6-8 feet to Virginia's coastline, the damage will be measured in billions of dollars. Much of Virginia Beach and Norfolk will be underwater due to the storm surge.
Hurricane Irene was a Class I storm when it passed through Hampton Roads in 2011, and it created 3.5-foot to 4.5-foot storm surges. State officials were relieved that the potential 8-foot surges predicted by some models did not occur. Local residents complained that impacts of the floding were exacerbated by sightseers in trucks with jacked-up suspensions, which created wakes that pushed water inches higher and into houses that otherwise might have stayed dry.6
observed water levels (red), predicted astronomic tide (blue), and the 4.4-foot storm surge (green) at Money Point in Portsmouth during Hurricane Irene
Source: Virginia Institute of Marine Science, Hurricane Irene Storm Tides
Superstorm Sandy in October, 2012 bypassed most of Virginia before slamming into New Jersey and New York City, but a future storm like it could redistribute the sands on Willoughby Spit and destroy all the development and the southern end of the Hampton Roads Bridge-Tunnel. A Class 3 hurricane will hit the Chesapeake Bay someday, and coastal cities are preparing for the inevitable.
Awareness of the flooding risk is increased by a local effort to document the "king tide," the highest tide predicted each year based on the alignments of the sun and moon. As described by the Virginia Institute of Marine Science (VIMS):7
During the king tide, the moon's orbit brings it closest to the earth for that year. Gravitational forces can push the normal high tide water levels as much as two feet higher. Volunteers use the SeaLevelRise app on their smart phones to help the Virginia Institute of Marine Science refine its models of which areas will flood. Citizen reports might reveal where culverts that are underwater only during a king tide, and not recorded in the LIDAR-based topographic layer in the model, can cause an area to flood unexpectedly.8
Source: YouTube, Sea Level Rise App - A Mapping Event
The Virginia Institute of Marine Science (VIMS) has even considered building a 24-mile long barrier at the mouth of the Chesapeake Bay, parallel to the bridge-tunnel, to block storm surges. The first step was 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) will come later.9
the storm surge from Hurricane Isabel was as high as six feet near West Point, on the York River
Source: National Oceanic and Atmospheric Administration (NOAA), Historical SLOSH Simulations - Isabel
Hurricane Isabel flooded homes along the Lafayette River in Norfolk
Source: Virginia Institute of Marine Science (VIMS), Norfolk Max. Flooding Extents during 2011 Hurricane Irene
sea level rise predictions
Source: US Fish and Wildlife Service, Vanishing Lands - Sea Level, Society, and Chesapeake Bay (Figure 10)
Superstorm Sandy in October, 2012 bypassed most of Virginia before slamming into New Jersey and New York City
storms such as Hurricane Isabel create storm surges on the coast, and also generate enough concentrated rainfall to flood valleys in the Blue Ridge
Source: National Aeronautics and Space Administration (NASA), Earth Observatory, Hurricane Isabel