The following are conclusions and observations found in the book, Hurricanes
and the Middle Atlantic States:
- The East Coast is in an active hurricane cycle, which began in 1995. Active cycles
typically last 25-30 years.
- During that time, there are often two or three quiet years, followed by significant
hurricane activity lasting one to four years. The Middle Atlantic states have well-defined
cycles of increased hurricane activity. It is as if someone turns on and off a faucet. Previous
active cycles in the region occurred from 1876 until 1904 and from 1933 until 1961. The
period from 1969 until 1979 brought the Mid-Atlantic several notable hurricane-related
floods. (From 2005 until 2008, the region saw little activity.)
- Hurricanes that occur within a month or two of each other, in the same general
geographic region, often take roughly parallel tracks.
- The region's climate is highly cyclical. Extremes are often followed by extremes. A
drought, for example, may be followed by a hurricane-related flood.
- Coastal sections are due for a major hurricane. Hurricane Gloria in 1985 was the last to
cause significant losses to Mid-Atlantic shore areas. The Great Atlantic Hurricane of 1944
was the last to cause severe damage along the shoreline from Virginia to New Jersey. The
Mid-Atlantic coast has had a dearth of major coastal hurricanes since the early 1960s.
Similar relatively quiet periods occurred from the late 1820s until the late 1870s, and for
about three decades during the early 20th century. These less active periods were followed
by many violent hurricanes affecting shore areas (and several destructive nor'easters).
- Interior sections are due for a highly destructive hurricane-related windstorm. Hurricane
Hazel in 1954 was the last tropical cyclone to carry actual hurricane-force winds through a
large section of the Mid-Atlantic interior, from Virginia to Pennsylvania. The region's
climatological history suggests that inland hurricanes such as Hazel occur about twice each
century. Similar events occurred in 1667, 1724, 1769, 1775, 1821, 1878 and 1896.
- The popular Saffir-Simpson hurricane intensity scale understates the potential for wind
damage in the Mid-Atlantic region. A Category 1 hurricane (sustained one-minute winds of
74-95 mph) can be expected to do widespread Category 2 and 3-type damage. Isolated
areas may see Category 4-type losses. Leafy trees and other vegetation, less wind-resistant
structures and infrastructure, as well as, perhaps, other yet to be identified factors are
responsible for the region's wind susceptibility.
- 'Major' hurricane Mid-Atlantic style: Meteorologists define a 'major' hurricane as
possessing at least Category 3 strength (sustained winds of at least 111 mph). Because of
the Middle Atlantic states' susceptibility to wind damage, a Category 1 hurricane (sustained
winds of 74-95 mph) tracking through interior sections will cause major destruction.
Furthermore, a tropical cyclone that stalls off the Mid-Atlantic coast for more than a day may
produce major shoreline damage even if it is something less than a Category 3.
- Tropical cyclones bring great variability in rainfall and winds over short distances.
Tropical Storm Hanna (Sept 2008), for example, dumped less than two inches of rain to
more than eight inches in the Washington, D.C., metropolitan area. Hurricane Isabel in Sept.
2003 lashed Washington and its suburbs with peak gusts ranging from less than 50 mph to
nearly 80 mph. A rapid forward speed, greater than 30 mph, tends to bring higher winds to
the surface, particularly in the northeastern sector when a storm moves in a northerly
direction.
- When evaluating the severe weather risk associated with a tropical cyclone, it is
important to consider the possibility of violent storms in the air mass ahead of the storm, in
adjacent weather systems, and in the air mass behind. The worst weather may occur
indirectly, outside the hurricane's circulation, sometimes days ahead or days after.
- The total drownings from hurricanes that remain offshore, with little or no effect on land,
exceeds those from the bigger storms written up in Hurricanes and the Middle Atlantic
States. So says Jay Mann, managing editor of the Beachcomber, Long Beach Island, N.J.,
and a long-time resident of the shore. Rip currents are to blame. They may form when a
hurricane comes within 1,000 miles of the Mid-Atlantic coast, while the storm is out to sea. A
sprawling hurricane will have the waters churning at 500 miles. The ocean claims lives even
as the sun shines. Often, a swimmer doesn't realize he is in a rip current until his strongest
efforts fail to bring him closer to shore. Swimming sideways perpendicular to shore may
break the grip of the rip, but all bets are off with a hurricane sea.
- The Mid-Atlantic region boasts some of the most intense short-term downpours on earth.
Some are related to tropical cyclones. Hurricane Camille, for example, dumped more than 27
inches of rain on sections of Nelson County, Va., within about five hours in August 1969.
Thunderstorms stalled by a hurricane off the New Jersey coast bucketed Ewan, N.J., (just 20
miles south of Philadelphia) with more than 22 inches in about 10 hours during September
1940.
- Hurricane deluges are of particular concern. Steep slopes in mountainous sections allow
rapid runoff. An extreme event, such as occurred with Hurricane Camille, can liquefy the soil
generating deadly mudflows. Meanwhile, urban sections, often situated on hilly terrain, are
at risk of flash flooding. Concrete, asphalt and other impervious surfaces reduce the
absorption of rainwater, increasing runoff. The monsoonal downpours of a tropical cyclone
can quickly turn destructive and deadly, as occurred with Hurricane Gaston in 2004 when it
pounded the Richmond, Va., metropolitan area with rainfall totals that topped 10 inches.
- Remnant systems tracking through the Mid-Atlantic region may spawn tornadoes. While
some become quite intense, they are usually short-lived, with intermittent tracks of less than
10 miles. Pinpointing where a tornado will touch down is beyond our present knowledge.
Eugene McCaul, a meteorologist and tornado researcher, puts the challenge and risk this
way: "Tropical cyclone tornadoes are often spawned by unusually small storm cells that may
not appear particularly dangerous on weather radar, especially if the cells are located more
than 60 miles from the radar. In addition, these small storms often tend to produce little or
no lightning or thunder, and may not look very visually threatening to the average person.
Furthermore, the tornadoes are often obscured by rain, and the storm cells spawning them
may move rapidly, leaving little time to take evasive action once the threat has been
perceived."
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